Apache Camel
USER GUIDE
Version 1.x-fuse-SNAPSHOT
Copyright 2007-2011, Apache Software Foundation
Table of Contents
Table of Contents ....................................................ii
Chapter 1
Introduction........................................................... 1
Chapter 2
Quickstart.............................................................. 1
Chapter 3
Getting Started ...................................................... 7
Chapter 4
Architecture.......................................................... 18
Chapter 5
Enterprise Integration Patterns .............................34
Chapter 6
Cook Book............................................................. 39
Chapter 7
Tutorials ............................................................. 109
Chapter 8
Language Appendix............................................. 221
Chapter 9
DataFormat Appendix.......................................... 293
Chapter 10
Pattern Appendix ................................................ 366
Chapter 11
Component Appendix .......................................... 524
Index ..................................................................... 0
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APA CH E C AM E L
CHAPTER
1
°°°°
Introduction
Apache Camel is a powerful open source integration framework based on
known Enterprise Integration Patterns with powerful Bean Integration.
Camel lets you create the Enterprise Integration Patterns to implement
routing and mediation rules in either a Java based Domain Specific Language
(or Fluent API), via Spring based Xml Configuration files or via the Scala DSL.
This means you get smart completion of routing rules in your IDE whether in
your Java, Scala or XML editor.
Apache Camel uses URIs so that it can easily work directly with any kind of
Transport or messaging model such as HTTP, ActiveMQ, JMS, JBI, SCA, MINA
or CXF Bus API together with working with pluggable Data Format options.
Apache Camel is a small library which has minimal dependencies for easy
embedding in any Java application. Apache Camel lets you work with the
same API regardless which kind of Transport used, so learn the API once and
you will be able to interact with all the Components that is provided out-ofthe-box.
Apache Camel has powerful Bean Binding and integrated seamless with
popular frameworks such as Spring and Guice.
Apache Camel has extensive Testing support allowing you to easily unit
test your routes.
Apache Camel can be used as a routing and mediation engine for the
following projects:
• Apache ServiceMix which is the most popular and powerful
distributed open source ESB and JBI container
• Apache ActiveMQ which is the most popular and powerful open
source message broker
• Apache CXF which is a smart web services suite (JAX-WS)
• Apache MINA a networking framework
So don't get the hump, try Camel today!
C HA P TE R 1 - IN TR O D U C TIO N
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CHAPTER
2
°°°°
Quickstart
To start using Apache Camel quickly, you can read through some simple
examples in this chapter. For readers who would like a more thorough
introduction, please skip ahead to Chapter 3.
WALK THROUGH AN EXAMPLE CODE
This mini-guide takes you through the source code of a simple example.
Camel can be configured either by using Spring or directly in Java - which
this example does.
We start with creating a CamelContext - which is a container for
Components, Routes etc:
CamelContext context = new DefaultCamelContext();
There is more than one way of adding a Component to the CamelContext.
You can add components implicitly - when we set up the routing - as we do
here for the FileComponent:
context.addRoutes(new RouteBuilder() {
public void configure() {
from("test-jms:queue:test.queue").to("file://test");
// set up a listener on the file component
from("file://test").process(new Processor() {
public void process(Exchange e) {
System.out.println("Received exchange: " + e.getIn());
}
});
}
});
or explicitly - as we do here when we add the JMS Component:
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CH AP T E R 2 - Q U I C K S TA RT
ConnectionFactory connectionFactory = new
ActiveMQConnectionFactory("vm://localhost?broker.persistent=false");
// Note we can explicit name the component
context.addComponent("test-jms",
JmsComponent.jmsComponentAutoAcknowledge(connectionFactory));
The above works with any JMS provider. If we know we are using ActiveMQ
we can use an even simpler form using the activeMQComponent() method
while specifying the brokerURL used to connect to ActiveMQ
camelContext.addComponent("activemq",
activeMQComponent("vm://localhost?broker.persistent=false"));
In normal use, an external system would be firing messages or events
directly into Camel through one if its Components but we are going to use
the ProducerTemplate which is a really easy way for testing your
configuration:
ProducerTemplate template = context.createProducerTemplate();
Next you must start the camel context. If you are using Spring to configure
the camel context this is automatically done for you; though if you are using
a pure Java approach then you just need to call the start() method
camelContext.start();
This will start all of the configured routing rules.
So after starting the CamelContext, we can fire some objects into camel:
for (int i = 0; i < 10; i++) {
template.sendBody("test-jms:queue:test.queue", "Test Message: " + i);
}
WHAT HAPPENS?
From the ProducerTemplate - we send objects (in this case text) into the
CamelContext to the Component test-jms:queue:test.queue. These text
objects will be converted automatically into JMS Messages and posted to a
JMS Queue named test.queue. When we set up the Route, we configured the
FileComponent to listen of the test.queue.
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The File FileComponent will take messages off the Queue, and save them
to a directory named test. Every message will be saved in a file that
corresponds to its destination and message id.
Finally, we configured our own listener in the Route - to take notifications
from the FileComponent and print them out as text.
That's it!
If you have the time then use 5 more minutes to Walk through another
example that demonstrates the Spring DSL (XML based) routing.
WALK THROUGH ANOTHER EXAMPLE
Introduction
We continue the walk from Walk through an Example. This time we take a
closer look at the routing and explains a few pointers so you wont walk into a
bear trap, but can enjoy a walk after hours to the local pub for a large beer
First we take a moment to look at the Enterprise Integration Patterns that
is the base pattern catalog for integrations. In particular we focus on the
Pipes and Filters EIP pattern, that is a central pattern. This is used for: route
through a sequence of processing steps, each performing a specific function much like the Java Servlet Filters.
Pipes and filters
In this sample we want to process a message in a sequence of steps where
each steps can perform their specific function. In our example we have a JMS
queue for receiving new orders. When an order is received we need to
process it in several steps:
▪ validate
▪ register
▪ send confirm email
This can be created in a route like this:
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Camel 1.4.0 change
In Camel 1.4.0, CamelTemplate has been marked as @deprecated.
ProducerTemplate should be used instead and its created from the
CamelContext itself.
ProducerTemplate template = context.createProducerTemplate();
Where as the bean ref is a reference for a spring bean id, so we define our
beans using regular Spring XML as:
Our validator bean is a plain POJO that has no dependencies to Camel what
so ever. So you can implement this POJO as you like. Camel uses rather
intelligent Bean Binding to invoke your POJO with the payload of the received
message. In this example we will not dig into this how this happens. You
should return to this topic later when you got some hands on experience with
Camel how it can easily bind routing using your existing POJO beans.
So what happens in the route above. Well when an order is received from
the JMS queue the message is routed like Pipes and Filters:
1. payload from the JMS is sent as input to the validateOrder bean
2. the output from validateOrder bean is sent as input to the registerOrder
bean
3. the output from registerOrder bean is sent as input to the
sendConfirmEmail bean
Using Camel Components
In the route lets imagine that the registration of the order has to be done by
sending data to a TCP socket that could be a big mainframe. As Camel has
many Components we will use the camel-mina component that supports TCP
connectivity. So we change the route to:
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Pipeline is default
In the route above we specify pipeline but it can be omitted as its
default, so you can write the route as:
uri="jms:queue:order"/>
ref="validateOrder"/>
ref="registerOrder"/>
ref="sendConfirmEmail"/>
This is commonly used not to state the pipeline.
An example where the pipeline needs to be used, is when using a
multicast and "one" of the endpoints to send to (as a logical group) is a
pipeline of other endpoints. For example.
The above sends the order (from jms:queue:order) to two locations at the
same time, our log component, and to the "pipeline" of beans which goes
one to the other. If you consider the opposite, sans the
you would see that multicast would not "flow" the message from one bean
to the next, but rather send the order to all 4 endpoints (1x log, 3x bean) in
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parallel, which is not (for this example) what we want. We need the
message to flow to the validateOrder, then to the registerOrder, then the
sendConfirmEmail so adding the pipeline, provides this facility.
What we now have in the route is a to type that can be used as a direct
replacement for the bean type. The steps is now:
1. payload from the JMS is sent as input to the validateOrder bean
2. the output from validateOrder bean is sent as text to the mainframe using
TCP
3. the output from mainframe is sent back as input to the sendConfirmEmai
bean
What to notice here is that the to is not the end of the route (the world
) in this example it's used in the middle of the Pipes and Filters. In fact we
can change the bean types to to as well:
As the to is a generic type we must state in the uri scheme which component
it is. So we must write bean: for the Bean component that we are using.
Conclusion
This example was provided to demonstrate the Spring DSL (XML based) as
opposed to the pure Java DSL from the first example. And as well to point
about that the to doesn't have to be the last node in a route graph.
This example is also based on the in-only message exchange pattern.
What you must understand as well is the in-out message exchange pattern,
where the caller expects a response. We will look into this in another
example.
See also
▪ Examples
▪ Tutorials
▪ User Guide
C HA P TE R 2 - Q U IC K S TA RT
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CHAPTER
3
°°°°
Getting Started with Apache
Camel
THE ENTERPRISE INTEGRATION PATTERNS (EIP) BOOK
The purpose of a "patterns" book is not to advocate new techniques that the
authors have invented, but rather to document existing best practices within
a particular field. By doing this, the authors of a patterns book hope to
spread knowledge of best practices and promote a vocabulary for discussing
architectural designs.
One of the most famous patterns books is Design Patterns: Elements of
Reusable Object-oriented Software by Erich Gamma, Richard Helm, Ralph
Johnson and John Vlissides, commonly known as the "Gang of Four" (GoF)
book. Since the publication of Design Patterns, many other pattern books, of
varying quality, have been written. One famous patterns book is called
Enterprise Integration Patterns: Designing, Building, and Deploying
Messaging Solutions by Gregor Hohpe and Bobby Woolf. It is common for
people to refer to this book by its initials EIP. As the subtitle of EIP suggests,
the book focuses on design patterns for asynchronous messaging systems.
The book discusses 65 patterns. Each pattern is given a textual name and
most are also given a graphical symbol, intended to be used in architectural
diagrams.
THE CAMEL PROJECT
Camel (http://camel.apache.org) is an open-source, Java-based project that
helps the user implement many of the design patterns in the EIP book.
Because Camel implements many of the design patterns in the EIP book, it
would be a good idea for people who work with Camel to have the EIP book
as a reference.
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ONLINE DOCUMENTATION FOR CAMEL
The documentation is all under the Documentation category on the right-side
menu of the Camel website (also available in PDF form. Camel-related books
are also available, in particular the Camel in Action book, presently serving
as the Camel bible--it has a free Chapter One (pdf), which is highly
recommended to read to get more familiar with Camel.
A useful tip for navigating the online documentation
The breadcrumbs at the top of the online Camel documentation can help you
navigate between parent and child subsections.
For example, If you are on the "Languages" documentation page then the
left-hand side of the reddish bar contains the following links.
Apache Camel > Documentation > Architecture > Languages
As you might expect, clicking on "Apache Camel" takes you back to the home
page of the Apache Camel project, and clicking on "Documentation" takes
you to the main documentation page. You can interpret the "Architecture"
and "Languages" buttons as indicating you are in the "Languages" section of
the "Architecture" chapter. Adding browser bookmarks to pages that you
frequently reference can also save time.
ONLINE JAVADOC DOCUMENTATION
The Apache Camel website provides Javadoc documentation. It is important
to note that the Javadoc documentation is spread over several independent
Javadoc hierarchies rather than being all contained in a single Javadoc
hierarchy. In particular, there is one Javadoc hierarchy for the core APIs of
Camel, and a separate Javadoc hierarchy for each component technology
supported by Camel. For example, if you will be using Camel with ActiveMQ
and FTP then you need to look at the Javadoc hierarchies for the core API and
Spring API.
CONCEPTS AND TERMINOLOGY FUNDAMENTAL TO CAMEL
In this section some of the concepts and terminology that are fundamental to
Camel are explained. This section is not meant as a complete Camel tutorial,
but as a first step in that direction.
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Endpoint
The term endpoint is often used when talking about inter-process
communication. For example, in client-server communication, the client is
one endpoint and the server is the other endpoint. Depending on the
context, an endpoint might refer to an address, such as a host:port pair for
TCP-based communication, or it might refer to a software entity that is
contactable at that address. For example, if somebody uses
"www.example.com:80" as an example of an endpoint, they might be
referring to the actual port at that host name (that is, an address), or they
might be referring to the web server (that is, software contactable at that
address). Often, the distinction between the address and software
contactable at that address is not an important one.
Some middleware technologies make it possible for several software entities
to be contactable at the same physical address. For example, CORBA is an
object-oriented, remote-procedure-call (RPC) middleware standard. If a
CORBA server process contains several objects then a client can
communicate with any of these objects at the same physical address
(host:port), but a client communicates with a particular object via that
object's logical address (called an IOR in CORBA terminology), which consists
of the physical address (host:port) plus an id that uniquely identifies the
object within its server process. (An IOR contains some additional information
that is not relevant to this present discussion.) When talking about CORBA,
some people may use the term "endpoint" to refer to a CORBA server's
physical address, while other people may use the term to refer to the logical
address of a single CORBA object, and other people still might use the term
to refer to any of the following:
• The physical address (host:port) of the CORBA server process
• The logical address (host:port plus id) of a CORBA object.
• The CORBA server process (a relatively heavyweight software entity)
• A CORBA object (a lightweight software entity)
Because of this, you can see that the term endpoint is ambiguous in at least
two ways. First, it is ambiguous because it might refer to an address or to a
software entity contactable at that address. Second, it is ambiguous in the
granularity of what it refers to: a heavyweight versus lightweight software
entity, or physical address versus logical address. It is useful to understand
that different people use the term endpoint in slightly different (and hence
ambiguous) ways because Camel's usage of this term might be different to
whatever meaning you had previously associated with the term.
Camel provides out-of-the-box support for endpoints implemented with many
different communication technologies. Here are some examples of the
Camel-supported endpoint technologies.
• A JMS queue.
• A web service.
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• A file. A file may sound like an unlikely type of endpoint, until you
realize that in some systems one application might write information
to a file and, later, another application might read that file.
• An FTP server.
• An email address. A client can send a message to an email address,
and a server can read an incoming message from a mail server.
• A POJO (plain old Java object).
In a Camel-based application, you create (Camel wrappers around) some
endpoints and connect these endpoints with routes, which I will discuss later
in Section 4.8 ("Routes, RouteBuilders and Java DSL"). Camel defines a Java
interface called Endpoint. Each Camel-supported endpoint has a class that
implements this Endpoint interface. As I discussed in Section 3.3 ("Online
Javadoc documentation"), Camel provides a separate Javadoc hierarchy for
each communications technology supported by Camel. Because of this, you
will find documentation on, say, the JmsEndpoint class in the JMS Javadoc
hierarchy, while documentation for, say, the FtpEndpoint class is in the FTP
Javadoc hierarchy.
CamelContext
A CamelContext object represents the Camel runtime system. You typically
have one CamelContext object in an application. A typical application
executes the following steps.
1. Create a CamelContext object.
2. Add endpoints – and possibly Components, which are discussed in
Section 4.5 ("Components") – to the CamelContext object.
3. Add routes to the CamelContext object to connect the endpoints.
4. Invoke the start() operation on the CamelContext object. This
starts Camel-internal threads that are used to process the sending,
receiving and processing of messages in the endpoints.
5. Eventually invoke the stop() operation on the CamelContext object.
Doing this gracefully stops all the endpoints and Camel-internal
threads.
Note that the CamelContext.start() operation does not block indefinitely.
Rather, it starts threads internal to each Component and Endpoint and then
start() returns. Conversely, CamelContext.stop() waits for all the threads
internal to each Endpoint and Component to terminate and then stop()
returns.
If you neglect to call CamelContext.start() in your application then
messages will not be processed because internal threads will not have been
created.
If you neglect to call CamelContext.stop() before terminating your
application then the application may terminate in an inconsistent state. If
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you neglect to call CamelContext.stop() in a JUnit test then the test may
fail due to messages not having had a chance to be fully processed.
CamelTemplate
Camel used to have a class called CamelClient, but this was renamed to be
CamelTemplate to be similar to a naming convention used in some other
open-source projects, such as the TransactionTemplate and JmsTemplate
classes in Spring.
The CamelTemplate class is a thin wrapper around the CamelContext class. It
has methods that send a Message or Exchange – both discussed in Section
4.6 ("Message and Exchange")) – to an Endpoint – discussed in Section 4.1
("Endpoint"). This provides a way to enter messages into source endpoints,
so that the messages will move along routes – discussed in Section 4.8
("Routes, RouteBuilders and Java DSL") – to destination endpoints.
The Meaning of URL, URI, URN and IRI
Some Camel methods take a parameter that is a URI string. Many people
know that a URI is "something like a URL" but do not properly understand the
relationship between URI and URL, or indeed its relationship with other
acronyms such as IRI and URN.
Most people are familiar with URLs (uniform resource locators), such as
"http://...", "ftp://...", "mailto:...". Put simply, a URL specifies the location of a
resource.
A URI (uniform resource identifier) is a URL or a URN. So, to fully understand
what URI means, you need to first understand what is a URN.
URN is an acronym for uniform resource name. There are may "unique
identifier" schemes in the world, for example, ISBNs (globally unique for
books), social security numbers (unique within a country), customer numbers
(unique within a company's customers database) and telephone numbers.
Each "unique identifier" scheme has its own notation. A URN is a wrapper for
different "unique identifier" schemes. The syntax of a URN is "urn::". A URN uniquely identifies a resource, such as a
book, person or piece of equipment. By itself, a URN does not specify the
location of the resource. Instead, it is assumed that a registry provides a
mapping from a resource's URN to its location. The URN specification does
not state what form a registry takes, but it might be a database, a server
application, a wall chart or anything else that is convenient. Some
hypothetical examples of URNs are "urn:employee:08765245",
"urn:customer:uk:3458:hul8" and "urn:foo:0000-0000-9E59-0000-5E-2". The
("employee", "customer" and "foo" in these examples) part
of a URN implicitly defines how to parse and interpret the that follows it. An arbitrary URN is meaningless unless: (1) you
know the semantics implied by the , and (2) you have
access to the registry appropriate for the . A registry does
not have to be public or globally accessible. For example,
"urn:employee:08765245" might be meaningful only within a specific
company.
To date, URNs are not (yet) as popular as URLs. For this reason, URI is widely
misused as a synonym for URL.
IRI is an acronym for internationalized resource identifier. An IRI is simply an
internationalized version of a URI. In particular, a URI can contain letters and
digits in the US-ASCII character set, while a IRI can contain those same
letters and digits, and also European accented characters, Greek letters,
Chinese ideograms and so on.
Components
Component is confusing terminology; EndpointFactory would have been
more appropriate because a Component is a factory for creating Endpoint
instances. For example, if a Camel-based application uses several JMS
queues then the application will create one instance of the JmsComponent
class (which implements the Component interface), and then the application
invokes the createEndpoint() operation on this JmsComponent object
several times. Each invocation of JmsComponent.createEndpoint() creates
an instance of the JmsEndpoint class (which implements the Endpoint
interface). Actually, application-level code does not invoke
Component.createEndpoint() directly. Instead, application-level code
normally invokes CamelContext.getEndpoint(); internally, the
CamelContext object finds the desired Component object (as I will discuss
shortly) and then invokes createEndpoint() on it.
Consider the following code.
myCamelContext.getEndpoint("pop3://john.smith@mailserv.example.com?password=myPassword");
The parameter to getEndpoint() is a URI. The URI prefix (that is, the part
before ":") specifies the name of a component. Internally, the CamelContext
object maintains a mapping from names of components to Component
objects. For the URI given in the above example, the CamelContext object
would probably map the pop3 prefix to an instance of the MailComponent
class. Then the CamelContext object invokes
createEndpoint("pop3://john.smith@mailserv.example.com?password=myPassword"
on that MailComponent object. The createEndpoint() operation splits the
URI into its component parts and uses these parts to create and configure an
Endpoint object.
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In the previous paragraph, I mentioned that a CamelContext object
maintains a mapping from component names to Component objects. This
raises the question of how this map is populated with named Component
objects. There are two ways of populating the map. The first way is for
application-level code to invoke CamelContext.addComponent(String
componentName, Component component). The example below shows a
single MailComponent object being registered in the map under 3 different
names.
Component mailComponent = new org.apache.camel.component.mail.MailComponent();
myCamelContext.addComponent("pop3", mailComponent);
myCamelContext.addComponent("imap", mailComponent);
myCamelContext.addComponent("smtp", mailComponent);
The second (and preferred) way to populate the map of named Component
objects in the CamelContext object is to let the CamelContext object perform
lazy initialization. This approach relies on developers following a convention
when they write a class that implements the Component interface. I illustrate
the convention by an example. Let's assume you write a class called
com.example.myproject.FooComponent and you want Camel to
automatically recognize this by the name "foo". To do this, you have to write
a properties file called "META-INF/services/org/apache/camel/component/foo"
(without a ".properties" file extension) that has a single entry in it called
class, the value of which is the fully-scoped name of your class. This is
shown below.
Listing 1. META-INF/services/org/apache/camel/component/foo
class=com.example.myproject.FooComponent
If you want Camel to also recognize the class by the name "bar" then you
write another properties file in the same directory called "bar" that has the
same contents. Once you have written the properties file(s), you create a jar
file that contains the com.example.myproject.FooComponent class and the
properties file(s), and you add this jar file to your CLASSPATH. Then, when
application-level code invokes createEndpoint("foo:...") on a
CamelContext object, Camel will find the "foo"" properties file on the
CLASSPATH, get the value of the class property from that properties file, and
use reflection APIs to create an instance of the specified class.
As I said in Section 4.1 ("Endpoint"), Camel provides out-of-the-box support
for numerous communication technologies. The out-of-the-box support
consists of classes that implement the Component interface plus properties
files that enable a CamelContext object to populate its map of named
Component objects.
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Earlier in this section I gave the following example of calling
CamelContext.getEndpoint().
myCamelContext.getEndpoint("pop3://john.smith@mailserv.example.com?password=myPassword");
When I originally gave that example, I said that the parameter to
getEndpoint() was a URI. I said that because the online Camel
documentation and the Camel source code both claim the parameter is a
URI. In reality, the parameter is restricted to being a URL. This is because
when Camel extracts the component name from the parameter, it looks for
the first ":", which is a simplistic algorithm. To understand why, recall from
Section 4.4 ("The Meaning of URL, URI, URN and IRI") that a URI can be a URL
or a URN. Now consider the following calls to getEndpoint.
myCamelContext.getEndpoint("pop3:...");
myCamelContext.getEndpoint("jms:...");
myCamelContext.getEndpoint("urn:foo:...");
myCamelContext.getEndpoint("urn:bar:...");
Camel identifies the components in the above example as "pop3", "jms",
"urn" and "urn". It would be more useful if the latter components were
identified as "urn:foo" and "urn:bar" or, alternatively, as "foo" and "bar" (that
is, by skipping over the "urn:" prefix). So, in practice you must identify an
endpoint with a URL (a string of the form ":...") rather than with a
URN (a string of the form "urn::..."). This lack of proper support for
URNs means the you should consider the parameter to getEndpoint() as
being a URL rather than (as claimed) a URI.
Message and Exchange
The Message interface provides an abstraction for a single message, such as
a request, reply or exception message.
There are concrete classes that implement the Message interface for each
Camel-supported communications technology. For example, the JmsMessage
class provides a JMS-specific implementation of the Message interface. The
public API of the Message interface provides get- and set-style methods to
access the message id, body and individual header fields of a messge.
The Exchange interface provides an abstraction for an exchange of
messages, that is, a request message and its corresponding reply or
exception message. In Camel terminology, the request, reply and exception
messages are called in, out and fault messages.
There are concrete classes that implement the Exchange interface for each
Camel-supported communications technology. For example, the JmsExchange
class provides a JMS-specific implementation of the Exchange interface. The
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public API of the Exchange interface is quite limited. This is intentional, and it
is expected that each class that implements this interface will provide its
own technology-specific operations.
Application-level programmers rarely access the Exchange interface (or
classes that implement it) directly. However, many classes in Camel are
generic types that are instantiated on (a class that implements) Exchange.
Because of this, the Exchange interface appears a lot in the generic
signatures of classes and methods.
Processor
The Processor interface represents a class that processes a message. The
signature of this interface is shown below.
Listing 2. Processor
package org.apache.camel;
public interface Processor {
void process(Exchange exchange) throws Exception;
}
Notice that the parameter to the process() method is an Exchange rather
than a Message. This provides flexibility. For example, an implementation of
this method initially might call exchange.getIn() to get the input message
and process it. If an error occurs during processing then the method can call
exchange.setException().
An application-level developer might implement the Processor interface
with a class that executes some business logic. However, there are many
classes in the Camel library that implement the Processor interface in a way
that provides support for a design pattern in the EIP book. For example,
ChoiceProcessor implements the message router pattern, that is, it uses a
cascading if-then-else statement to route a message from an input queue to
one of several output queues. Another example is the FilterProcessor
class which discards messages that do not satisfy a stated predicate (that is,
condition).
Routes, RouteBuilders and Java DSL
A route is the step-by-step movement of a Message from an input queue,
through arbitrary types of decision making (such as filters and routers) to a
destination queue (if any). Camel provides two ways for an application
developer to specify routes. One way is to specify route information in an
XML file. A discussion of that approach is outside the scope of this document.
The other way is through what Camel calls a Java DSL (domain-specific
language).
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Introduction to Java DSL
For many people, the term "domain-specific language" implies a compiler or
interpreter that can process an input file containing keywords and syntax
specific to a particular domain. This is not the approach taken by Camel.
Camel documentation consistently uses the term "Java DSL" instead of
"DSL", but this does not entirely avoid potential confusion. The Camel "Java
DSL" is a class library that can be used in a way that looks almost like a DSL,
except that it has a bit of Java syntactic baggage. You can see this in the
example below. Comments afterwards explain some of the constructs used in
the example.
Listing 3. Example of Camel's "Java DSL"
RouteBuilder builder = new RouteBuilder() {
public void configure() {
from("queue:a").filter(header("foo").isEqualTo("bar")).to("queue:b");
from("queue:c").choice()
.when(header("foo").isEqualTo("bar")).to("queue:d")
.when(header("foo").isEqualTo("cheese")).to("queue:e")
.otherwise().to("queue:f");
}
};
CamelContext myCamelContext = new DefaultCamelContext();
myCamelContext.addRoutes(builder);
The first line in the above example creates an object which is an instance of
an anonymous subclass of RouteBuilder with the specified configure()
method.
The CamelContext.addRoutes(RouterBuilder builder) method invokes
builder.setContext(this) – so the RouteBuilder object knows which
CamelContext object it is associated with – and then invokes
builder.configure(). The body of configure() invokes methods such as
from(), filter(), choice(), when(), isEqualTo(), otherwise() and to().
The RouteBuilder.from(String uri) method invokes getEndpoint(uri)
on the CamelContext associated with the RouteBuilder object to get the
specified Endpoint and then puts a FromBuilder "wrapper" around this
Endpoint. The FromBuilder.filter(Predicate predicate) method
creates a FilterProcessor object for the Predicate (that is, condition)
object built from the header("foo").isEqualTo("bar") expression. In this
way, these operations incrementally build up a Route object (with a
RouteBuilder wrapper around it) and add it to the CamelContext object
associated with the RouteBuilder.
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Critique of Java DSL
The online Camel documentation compares Java DSL favourably against the
alternative of configuring routes and endpoints in a XML-based Spring
configuration file. In particular, Java DSL is less verbose than its XML
counterpart. In addition, many integrated development environments (IDEs)
provide an auto-completion feature in their editors. This auto-completion
feature works with Java DSL, thereby making it easier for developers to write
Java DSL.
However, there is another option that the Camel documentation neglects to
consider: that of writing a parser that can process DSL stored in, say, an
external file. Currently, Camel does not provide such a DSL parser, and I do
not know if it is on the "to do" list of the Camel maintainers. I think that a
DSL parser would offer a significant benefit over the current Java DSL. In
particular, the DSL would have a syntactic definition that could be expressed
in a relatively short BNF form. The effort required by a Camel user to learn
how to use DSL by reading this BNF would almost certainly be significantly
less than the effort currently required to study the API of the RouterBuilder
classes.
Continue Learning about Camel
Return to the main Getting Started page for additional introductory reference
information.
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CHAPTER
4
°°°°
Architecture
Camel uses a Java based Routing Domain Specific Language (DSL) or an Xml
Configuration to configure routing and mediation rules which are added to a
CamelContext to implement the various Enterprise Integration Patterns.
At a high level Camel consists of a CamelContext which contains a
collection of Component instances. A Component is essentially a factory of
Endpoint instances. You can explicitly configure Component instances in Java
code or an IoC container like Spring or Guice, or they can be auto-discovered
using URIs.
An Endpoint acts rather like a URI or URL in a web application or a
Destination in a JMS system; you can communicate with an endpoint; either
sending messages to it or consuming messages from it. You can then create
a Producer or Consumer on an Endpoint to exchange messages with it.
The DSL makes heavy use of pluggable Languages to create an Expression
or Predicate to make a truly powerful DSL which is extensible to the most
suitable language depending on your needs. The following languages are
supported
• Bean Language for using Java for expressions
• Constant
• the unified EL from JSP and JSF
• Header
• JXPath
• Mvel
• OGNL
• Ref Language
• Property
• Scala DSL
• Scripting Languages such as
◦ BeanShell
◦ JavaScript
◦ Groovy
◦ Python
◦ PHP
◦ Ruby
• Simple
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◦ File Language
• Spring Expression Language
• SQL
• Tokenizer
• XPath
• XQuery
Most of these languages is also supported used as Annotation Based
Expression Language.
For a full details of the individual languages see the Language Appendix
URIS
Camel makes extensive use of URIs to allow you to refer to endpoints which
are lazily created by a Component if you refer to them within Routes
Current Supported URIs
Component / ArtifactId / URI
AHC / camel-ahc
ahc:hostname:[port]
Description
To call external HTTP
services using Async Http
Client
AMQP / camel-amqp
amqp:[topic:]destinationName
For Messaging with AMQP
protocol
APNS / camel-apns
apns:notify[?options]
Atom / camel-atom
atom:uri
AWS-SNS / camel-aws
aws-sns://topicname[?options]
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CH AP T E R 4 - A R C H I T E C T U R E
For sending notifications to
Apple iOS devices
Working with Apache
Abdera for atom integration,
such as consuming an atom
feed.
For Messaging with
Amazon's Simple
Notification Service (SNS).
AWS-SQS / camel-aws
aws-sqs://queuename[?options]
For Messaging with
Amazon's Simple Queue
Service (SQS).
AWS-S3 / camel-aws
aws-s3://bucketname[?options]
Bean / camel-core
bean:beanName[?method=someMethod]
Bean Validation / camel-bean-validator
bean-validator:something
Browse / camel-core
browse:someName
Cache / camel-cache
cache://cachename[?options]
Class / camel-core
class:className[?method=someMethod]
For working with Amazon's
Simple Storage Service (S3).
Uses the Bean Binding to
bind message exchanges to
beans in the Registry. Is also
used for exposing and
invoking POJO (Plain Old
Java Objects).
Validates the payload of a
message using the Java
Validation API (JSR 303 and
JAXP Validation) and its
reference implementation
Hibernate Validator
Provides a simple
BrowsableEndpoint which
can be useful for testing,
visualisation tools or
debugging. The exchanges
sent to the endpoint are all
available to be browsed.
The cache component
facilitates creation of
caching endpoints and
processors using EHCache
as the cache
implementation.
Uses the Bean Binding to
bind message exchanges to
beans in the Registry. Is also
used for exposing and
invoking POJO (Plain Old
Java Objects).
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Cometd / camel-cometd
cometd://host:port/channelname
Context / camel-context
context:camelContextId:localEndpointName
Crypto (Digital Signatures) / camel-crypto
crypto:sign:name[?options]
crypto:verify:name[?options]
Used to deliver messages
using the jetty cometd
implementation of the
bayeux protocol
Used to refer to endpoints
within a separate
CamelContext to provide a
simple black box
composition approach so
that routes can be combined
into a CamelContext and
then used as a black box
component inside other
routes in other
CamelContexts
Used to sign and verify
exchanges using the
Signature Service of the
Java Cryptographic
Extension.
CXF / camel-cxf
cxf:address[?serviceClass=...]
CXF Bean / camel-cxf
cxf:bean name
CXFRS / camel-cxf
cxfrs:address[?resourcesClasses=...]
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CH AP T E R 4 - A R C H I T E C T U R E
Working with Apache CXF
for web services integration
Proceess the exchange
using a JAX WS or JAX RS
annotated bean from the
registry. Requires less
configuration than the
above CXF Component
Working with Apache CXF
for REST services
integration
DataSet / camel-core
dataset:name
For load & soak testing the
DataSet provides a way to
create huge numbers of
messages for sending to
Components or asserting
that they are consumed
correctly
Direct / camel-core
direct:name
DNS / camel-dns
dns:operation
EJB / camel-ejb
ejb:ejbName[?method=someMethod]
Synchronous call to another
endpoint
To lookup domain
information and run DNS
queries using DNSJava
Uses the Bean Binding to
bind message exchanges to
EJBs. It works like the Bean
component but just for
accessing EJBs. Supports EJB
3.0 onwards.
Event / camel-spring
event://default
spring-event://default
Working with Spring
ApplicationEvents
EventAdmin / camel-eventadmin
eventadmin:topic
Receiving OSGi EventAdmin
events
Exec / camel-exec
exec://executable[?options]
File / camel-core
file://nameOfFileOrDirectory
For executing system
commands
Sending messages to a file
or polling a file or directory.
Camel 1.x use this link
File.
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22
Flatpack / camel-flatpack
flatpack:[fixed|delim]:configFile
Processing fixed width or
delimited files or messages
using the FlatPack library
FreeMarker / camel-freemarker
freemarker:someTemplateResource
FTP / camel-ftp
ftp://host[:port]/fileName
FTPS / camel-ftp
ftps://host[:port]/fileName
GAuth / camel-gae
gauth://name[?options]
GHttp / camel-gae
ghttp://hostname[:port][/path][?options]
ghttp:///path[?options]
GLogin / camel-gae
glogin://hostname[:port][?options]
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Generates a response using
a FreeMarker template
Sending and receiving files
over FTP. Camel 1.x use
this link FTP.
Sending and receiving files
over FTP Secure (TLS and
SSL).
Used by web applications to
implement an OAuth
consumer. See also Camel
Components for Google App
Engine.
Provides connectivity to the
URL fetch service of Google
App Engine but can also be
used to receive messages
from servlets. See also
Camel Components for
Google App Engine.
Used by Camel applications
outside Google App Engine
(GAE) for programmatic
login to GAE applications.
See also Camel Components
for Google App Engine.
GTask / camel-gae
gtask://queue-name
GMail / camel-gae
gmail://user@gmail.com[?options]
gmail://user@googlemail.com[?options]
Hazelcast / camel-hazelcast
hazelcast://[type]:cachename[?options]
Supports asynchronous
message processing on
Google App Engine by using
the task queueing service as
message queue. See also
Camel Components for
Google App Engine.
Supports sending of emails
via the mail service of
Google App Engine. See also
Camel Components for
Google App Engine.
Hazelcast is a data grid
entirely implemented in Java
(single jar). This component
supports map, multimap,
seda, queue, set, atomic
number and simple cluster
support.
HDFS / camel-hdfs
hdfs://path[?options]
HL7 / camel-hl7
mina:tcp://hostname[:port]
HTTP / camel-http
http://hostname[:port]
HTTP4 / camel-http4
http4://hostname[:port]
iBATIS / camel-ibatis
ibatis://statementName
For reading/writing from/to
an HDFS filesystem
For working with the HL7
MLLP protocol and the HL7
model using the HAPI library
For calling out to external
HTTP servers using Apache
HTTP Client 3.x
For calling out to external
HTTP servers using Apache
HTTP Client 4.x
Performs a query, poll,
insert, update or delete in a
relational database using
Apache iBATIS
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IMap / camel-mail
imap://hostname[:port]
Receiving email using IMap
IRC / camel-irc
irc:host[:port]/#room
JavaSpace / camel-javaspace
javaspace:jini://host?spaceName=mySpace?...
JBI / servicemix-camel
jbi:serviceName
jclouds / jclouds
jclouds:[blobstore|computservice]:provider
JCR / camel-jcr
jcr://user:password@repository/path/to/node
For IRC communication
Sending and receiving
messages through
JavaSpace
For JBI integration such as
working with Apache
ServiceMix
For interacting with cloud
compute & blobstore service
via jclouds
Storing a message in a JCR
compliant repository like
Apache Jackrabbit
JDBC / camel-jdbc
jdbc:dataSourceName?options
For performing JDBC queries
and operations
Jetty / camel-jetty
jetty:url
For exposing services over
HTTP
JMS / camel-jms
jms:[topic:]destinationName
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Working with JMS providers
JMX / camel-jmx
jmx://platform?options
JPA / camel-jpa
jpa://entityName
JT/400 / camel-jt400
jt400://user:pwd@system/
Kestrel / camel-kestrel
kestrel://[addresslist/]queuename[?options]
Krati / camel-krati
krati://[path to datastore/][?options]
For working with JMX
notification listeners
For using a database as a
queue via the JPA
specification for working
with OpenJPA, Hibernate or
TopLink
For integrating with data
queues on an AS/400 (aka
System i, IBM i, i5, ...)
system
For producing to or
consuming from Kestrel
queues
For producing to or
consuming to Krati
datastores
Language / camel-core
language://languageName[:script][?options]
LDAP / camel-ldap
ldap:host[:port]?base=...[&scope=]
Log / camel-core
log:loggingCategory[?level=ERROR]
Executes Languages scripts
Performing searches on
LDAP servers (
must be one of
object|onelevel|subtree)
Uses Jakarta Commons
Logging to log the message
exchange to some
underlying logging system
like log4j
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26
Lucene / camel-lucene
lucene:searcherName:insert[?analyzer=]
lucene:searcherName:query[?analyzer=]
Uses Apache Lucene to
perform Java-based indexing
and full text based searches
using advanced analysis/
tokenization capabilities
Mail / camel-mail
mail://user-info@host:port
Sending and receiving email
MINA / camel-mina
[tcp|udp|vm]:host[:port]
Working with Apache MINA
Mock / camel-core
mock:name
MSV / camel-msv
msv:someLocalOrRemoteResource
MyBatis / camel-mybatis
mybatis://statementName
For testing routes and
mediation rules using mocks
Validates the payload of a
message using the MSV
Library
Performs a query, poll,
insert, update or delete in a
relational database using
MyBatis
Nagios / camel-nagios
nagios://host[:port]?options
Netty / camel-netty
netty:tcp//host[:port]?options
netty:udp//host[:port]?options
Sending passive checks to
Nagios using JSendNSCA
Working with TCP and UDP
protocols using Java NIO
based capabilities offered by
the JBoss Netty community
project
Pax-Logging / camel-paxlogging
paxlogging:appender
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Receiving Pax-Logging
events in OSGi
POP / camel-mail
pop3://user-info@host:port
Printer / camel-printer
lpr://host:port/path/to/printer[?options]
Properties / camel-core
properties://key[?options]
Quartz / camel-quartz
quartz://groupName/timerName
Quickfix / camel-quickfix
quickfix-server:config file
quickfix-client:config-file
Ref / camel-core
ref:name
Restlet / camel-restlet
restlet:restletUrl[?options]
Receiving email using POP3
and JavaMail
The printer component
facilitates creation of printer
endpoints to local, remote
and wireless printers. The
endpoints provide the ability
to print camel directed
payloads when utilized on
camel routes.
The properties component
facilitates using property
placeholders directly in
endpoint uri definitions.
Provides a scheduled
delivery of messages using
the Quartz scheduler
Implementation of the
QuickFix for Java engine
which allow to send/receive
FIX messages
Component for lookup of
existing endpoints bound in
the Registry.
Component for consuming
and producing Restful
resources using Restlet
RMI / camel-rmi
rmi://host[:port]
Working with RMI
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28
RNC / camel-jing
rnc:/relativeOrAbsoluteUri
Validates the payload of a
message using RelaxNG
Compact Syntax
RNG / camel-jing
rng:/relativeOrAbsoluteUri
Routebox / camel-routebox
routebox:routeboxName[?options]
RSS / camel-rss
rss:uri
SEDA / camel-core
seda:name
SERVLET / camel-servlet
servlet:uri
SFTP / camel-ftp
sftp://host[:port]/fileName
Sip / camel-sip
sip://user@host[:port]?[options]
sips://user@host[:port]?[options]
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Validates the payload of a
message using RelaxNG
Facilitates the creation of
specialized endpoints that
offer encapsulation and a
strategy/map based
indirection service to a
collection of camel routes
hosted in an automatically
created or user injected
camel context
Working with ROME for RSS
integration, such as
consuming an RSS feed.
Asynchronous call to
another endpoint in the
same Camel Context
For exposing services over
HTTP through the servlet
which is deployed into the
Web container.
Sending and receiving files
over SFTP (FTP over SSH).
Camel 1.x use this link
FTP.
Publish/Subscribe
communication capability
using the Telecom SIP
protocol. RFC3903 - Session
Initiation Protocol (SIP)
Extension for Event
SMTP / camel-mail
smtp://user-info@host[:port]
SMPP / camel-smpp
smpp://user-info@host[:port]?options
SNMP / camel-snmp
snmp://host[:port]?options
SpringIntegration / camel-spring-integration
spring-integration:defaultChannelName
Spring Web Services / camel-spring-ws
spring-ws:[mapping-type:]address[?options]
Sending email using SMTP
and JavaMail
To send and receive SMS
using Short Messaging
Service Center using the
JSMPP library
Polling OID values and
receiving traps using SNMP
via SNMP4J library
The bridge component of
Camel and Spring
Integration
Client-side support for
accessing web services, and
server-side support for
creating your own contractfirst web services using
Spring Web Services
SQL / camel-sql
sql:select * from table where id=#
Stream / camel-stream
stream:[in|out|err|file]
Performing SQL queries
using JDBC
Read or write to an input/
output/error/file stream
rather like unix pipes
StringTemplate / camel-stringtemplate
string-template:someTemplateResource
Generates a response using
a String Template
TCP / camel-mina
mina:tcp://host:port
Working with TCP protocols
using Apache MINA
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Test / camel-spring
test:expectedMessagesEndpointUri
Creates a Mock endpoint
which expects to receive all
the message bodies that
could be polled from the
given underlying endpoint
Timer / camel-core
timer://name
A timer endpoint
UDP / camel-mina
mina:udp://host:port
Validation / camel-core (camel-spring for
Camel 2.8 or older)
validation:someLocalOrRemoteResource
Working with UDP protocols
using Apache MINA
Validates the payload of a
message using XML Schema
and JAXP Validation
Velocity / camel-velocity
velocity:someTemplateResource
VM / camel-core
vm:name
Generates a response using
an Apache Velocity template
Asynchronous call to
another endpoint in the
same JVM
XMPP / camel-xmpp
xmpp://host:port/room
Working with XMPP and
Jabber
XQuery / camel-saxon
xquery:someXQueryResource
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Generates a response using
an XQuery template
XSLT / camel-core (camel-spring for Camel
2.8 or older)
xslt:someTemplateResource
Generates a response using
an XSLT template
Zookeeper / camel-zookeeper
Working with ZooKeeper
cluster(s)
zookeeper://host:port/path
URI's for external components
Other projects and companies have also created Camel components to
integrate additional functionality into Camel. These components may be
provided under licenses that are not compatible with the Apache License, use
libraries that are not compatible, etc... These components are not supported
by the Camel team, but we provide links here to help users find the
additional functionality.
Component / ArtifactId / URI
License
Description
Apache
For JMS Messaging with
Apache ActiveMQ
Apache
Uses ActiveMQ's fast
disk journaling
implementation to store
message bodies in a
rolling log file
GPL
For using a db4o
datastore as a queue via
the db4o library
GPL
Working with the Esper
Library for Event Stream
Processing
ActiveMQ / activemq-camel
activemq:[topic:]destinationName
ActiveMQ Journal / activemq-core
activemq.journal:directory-on-filesystem
Db4o / camel-db4o in camel-extra
db4o://className
Esper / camel-esper in camel-extra
esper:name
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Hibernate / camel-hibernate in
camel-extra
GPL
For using a database as
a queue via the
Hibernate library
Apache
Integration with the
Normalized Message
Router BUS in
ServiceMix 4.x
Apache
Uses the given Scalate
template to transform
the message
GPL
For working with EDI
parsing using the
Smooks library. This
component is
deprecated as Smooks
now provides Camel
integration out of the
box
hibernate://entityName
NMR / servicemix-nmr
nmr://serviceName
Scalate / scalate-camel
scalate:templateName
Smooks / camel-smooks in camelextra.
unmarshal(edi)
For a full details of the individual components see the Component Appendix
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CH AP T E R 4 - A R C H I T E C T U R E
CHAPTER
5
°°°°
Enterprise Integration
Patterns
Camel supports most of the Enterprise Integration Patterns from the
excellent book of the same name by Gregor Hohpe and Bobby Woolf. Its a
highly recommended book, particularly for users of Camel.
PATTERN INDEX
There now follows a list of the Enterprise Integration Patterns from the book
along with examples of the various patterns using Apache Camel
Messaging Systems
Message
Channel
How does one application communicate with
another using messaging?
Message
How can two applications connected by a message
channel exchange a piece of information?
Pipes and
Filters
How can we perform complex processing on a
message while maintaining independence and
flexibility?
Message
Router
How can you decouple individual processing steps
so that messages can be passed to different filters
depending on a set of conditions?
Message
Translator
How can systems using different data formats
communicate with each other using messaging?
Message
Endpoint
How does an application connect to a messaging
channel to send and receive messages?
C HA P T E R 5 - E N T E R PR ISE IN TE GR ATIO N PAT TE R N S
34
Messaging Channels
Point to
Point
Channel
How can the caller be sure that exactly one
receiver will receive the document or perform the
call?
Publish
Subscribe
Channel
How can the sender broadcast an event to all
interested receivers?
Dead Letter
Channel
What will the messaging system do with a
message it cannot deliver?
Guaranteed
Delivery
How can the sender make sure that a message
will be delivered, even if the messaging system
fails?
Message
Bus
What is an architecture that enables separate
applications to work together, but in a de-coupled
fashion such that applications can be easily added
or removed without affecting the others?
Message Construction
Event
Message
How can messaging be used to transmit events
from one application to another?
Request
Reply
When an application sends a message, how can it
get a response from the receiver?
Correlation
Identifier
How does a requestor that has received a reply
know which request this is the reply for?
Return
Address
How does a replier know where to send the reply?
Message Routing
35
Content
Based
Router
How do we handle a situation where the
implementation of a single logical function (e.g.,
inventory check) is spread across multiple
physical systems?
Message
Filter
How can a component avoid receiving
uninteresting messages?
CH AP T E R 5 - E N T E R P R I S E I N T E G R ATIO N PAT TE R N S
Dynamic
Router
How can you avoid the dependency of the
router on all possible destinations while
maintaining its efficiency?
Recipient
List
How do we route a message to a list of (static or
dynamically) specified recipients?
Splitter
How can we process a message if it contains
multiple elements, each of which may have to
be processed in a different way?
Aggregator
How do we combine the results of individual,
but related messages so that they can be
processed as a whole?
Resequencer
How can we get a stream of related but out-ofsequence messages back into the correct order?
Composed
Message
Processor
How can you maintain the overall message flow
when processing a message consisting of
multiple elements, each of which may require
different processing?
ScatterGather
How do you maintain the overall message flow
when a message needs to be sent to multiple
recipients, each of which may send a reply?
Routing Slip
How do we route a message consecutively
through a series of processing steps when the
sequence of steps is not known at design-time
and may vary for each message?
Throttler
How can I throttle messages to ensure that a
specific endpoint does not get overloaded, or
we don't exceed an agreed SLA with some
external service?
Sampling
How can I sample one message out of many in a
given period to avoid downstream route does
not get overloaded?
Delayer
How can I delay the sending of a message?
Load
Balancer
How can I balance load across a number of
endpoints?
Multicast
How can I route a message to a number of
endpoints at the same time?
C HA P T E R 5 - E N T E R PR ISE IN TE GR ATIO N PAT TE R N S
36
Loop
How can I repeat processing a message in a
loop?
Message Transformation
Content
Enricher
How do we communicate with another system if
the message originator does not have all the
required data items available?
Content
Filter
How do you simplify dealing with a large message,
when you are interested only in a few data items?
Claim
Check
How can we reduce the data volume of message
sent across the system without sacrificing
information content?
Normalizer
How do you process messages that are
semantically equivalent, but arrive in a different
format?
Sort
How can I sort the body of a message?
Validate
How can I validate a message?
Messaging Endpoints
37
Messaging
Mapper
How do you move data between domain objects
and the messaging infrastructure while keeping
the two independent of each other?
Event Driven
Consumer
How can an application automatically consume
messages as they become available?
Polling
Consumer
How can an application consume a message
when the application is ready?
Competing
Consumers
How can a messaging client process multiple
messages concurrently?
Message
Dispatcher
How can multiple consumers on a single channel
coordinate their message processing?
Selective
Consumer
How can a message consumer select which
messages it wishes to receive?
Durable
Subscriber
How can a subscriber avoid missing messages
while it's not listening for them?
CH AP T E R 5 - E N T E R P R I S E I N T E G R ATIO N PAT TE R N S
Idempotent
Consumer
How can a message receiver deal with duplicate
messages?
Transactional
Client
How can a client control its transactions with the
messaging system?
Messaging
Gateway
How do you encapsulate access to the
messaging system from the rest of the
application?
Service
Activator
How can an application design a service to be
invoked both via various messaging technologies
and via non-messaging techniques?
System Management
Detour
How can you route a message through intermediate
steps to perform validation, testing or debugging
functions?
Wire
Tap
How do you inspect messages that travel on a point-topoint channel?
Log
How can I log processing a message?
For a full breakdown of each pattern see the Book Pattern Appendix
C HA P T E R 5 - E N T E R PR ISE IN TE GR ATIO N PAT TE R N S
38
CookBook
This document describes various recipes for working with Camel
• Bean Integration describes how to work with beans and Camel in a
loosely coupled way so that your beans do not have to depend on
any Camel APIs
◦ Annotation Based Expression Language binds expressions to
method parameters
◦ Bean Binding defines which methods are invoked and how
the Message is converted into the parameters of the method
when it is invoked
◦ Bean Injection for injecting Camel related resources into your
POJOs
◦ Parameter Binding Annotations for extracting various
headers, properties or payloads from a Message
◦ POJO Consuming for consuming and possibly routing
messages from Camel
◦ POJO Producing for producing camel messages from your
POJOs
◦ RecipientList Annotation for creating a Recipient List from a
POJO method
◦ Using Exchange Pattern Annotations describes how pattern
annotations can be used to change the behaviour of method
invocations
• Hiding Middleware describes how to avoid your business logic being
coupled to any particular middleware APIs allowing you to easily
switch from in JVM SEDA to JMS, ActiveMQ, Hibernate, JPA, JDBC,
iBATIS or JavaSpace etc.
• Visualisation describes how to visualise your Enterprise Integration
Patterns to help you understand your routing rules
• Business Activity Monitoring (BAM) for monitoring business processes
across systems
• Extract Transform Load (ETL) to load data into systems or databases
• Testing for testing distributed and asynchronous systems using a
messaging approach
◦ Camel Test for creating test cases using a single Java class
for all your configuration and routing
◦ Spring Testing uses Spring Test together with either XML or
Java Config to dependency inject your test classes
◦ Guice uses Guice to dependency inject your test classes
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COOKBOOK
• Templating is a great way to create service stubs to be able to test
your system without some back end system.
• Database for working with databases
• Parallel Processing and Ordering on how using parallel processing
and SEDA or JMS based load balancing can be achieved.
• Asynchronous Processing in Camel Routes.
• Implementing Virtual Topics on other JMS providers shows how to get
the effect of Virtual Topics and avoid issues with JMS durable topics
• Camel Transport for CXF describes how to put the Camel context into
the CXF transport layer.
• Fine Grained Control Over a Channel describes how to deliver a
sequence of messages over a single channel and then stopping any
more messages being sent over that channel. Typically used for
sending data over a socket and then closing the socket.
• EventNotifier to log details about all sent Exchanges shows how to let
Camels EventNotifier log all sent to endpoint events and how long
time it took.
• Loading routes from XML files into an existing CamelContext.
• Using MDC logging with Camel
• Running Camel standalone and have it keep running shows how to
keep Camel running when you run it standalone.
• Hazelcast Idempotent Repository Tutorial shows how to avoid to
consume duplicated messages in a clustered environment.
BEAN INTEGRATION
Camel supports the integration of beans and POJOs in a number of ways
Annotations
If a bean is defined in Spring XML or scanned using the Spring component
scanning mechanism and a is used or a
CamelBeanPostProcessor then we process a number of Camel annotations
to do various things such as injecting resources or producing, consuming or
routing messages.
• POJO Consuming to consume and possibly route messages from
Camel
• POJO Producing to make it easy to produce camel messages from
your POJOs
• DynamicRouter Annotation for creating a Dynamic Router from a
POJO method
• RecipientList Annotation for creating a Recipient List from a POJO
method
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• RoutingSlip Annotation for creating a Routing Slip for a POJO method
• Bean Injection to inject Camel related resources into your POJOs
• Using Exchange Pattern Annotations describes how the pattern
annotations can be used to change the behaviour of method
invocations with Spring Remoting or POJO Producing
Bean Component
The Bean component allows one to invoke a particular method. Alternately
the Bean component supports the creation of a proxy via ProxyHelper to a
Java interface; which the implementation just sends a message containing a
BeanInvocation to some Camel endpoint.
Spring Remoting
We support a Spring Remoting provider which uses Camel as the underlying
transport mechanism. The nice thing about this approach is we can use any
of the Camel transport Components to communicate between beans. It also
means we can use Content Based Router and the other Enterprise Integration
Patterns in between the beans; in particular we can use Message Translator
to be able to convert what the on-the-wire messages look like in addition to
adding various headers and so forth.
Annotation Based Expression Language
You can also use any of the Languages supported in Camel to bind
expressions to method parameters when using Bean Integration. For
example you can use any of these annotations:
41
Annotation
Description
@Bean
Inject a Bean expression
@BeanShell
Inject a BeanShell expression
@Constant
Inject a Constant expression
@EL
Inject an EL expression
@Groovy
Inject a Groovy expression
@Header
Inject a Header expression
@JavaScript
Inject a JavaScript expression
@MVEL
Inject a Mvel expression
@OGNL
Inject an OGNL expression
COOKBOOK
Bean binding
Whenever Camel invokes a bean method via one of the above
methods (Bean component, Spring Remoting or POJO Consuming)
then the Bean Binding mechanism is used to figure out what
method to use (if it is not explicit) and how to bind the Message to
the parameters possibly using the Parameter Binding Annotations
or using a method name option.
@PHP
Inject a PHP expression
@Python
Inject a Python expression
@Ruby
Inject a Ruby expression
@Simple
Inject an Simple expression
@XPath
Inject an XPath expression
@XQuery
Inject an XQuery expression
Example:
public class Foo {
@MessageDriven(uri = "activemq:my.queue")
public void doSomething(@XPath("/foo/bar/text()") String correlationID, @Body
String body) {
// process the inbound message here
}
}
Advanced example using @Bean
And an example of using the the @Bean binding annotation, where you can
use a Pojo where you can do whatever java code you like:
public class Foo {
@MessageDriven(uri = "activemq:my.queue")
public void doSomething(@Bean("myCorrelationIdGenerator") String correlationID,
@Body String body) {
// process the inbound message here
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}
}
And then we can have a spring bean with the id
myCorrelationIdGenerator where we can compute the id.
public class MyIdGenerator {
private UserManager userManager;
public String generate(@Header(name = "user") String user, @Body String payload)
throws Exception {
User user = userManager.lookupUser(user);
String userId = user.getPrimaryId();
String id = userId + generateHashCodeForPayload(payload);
return id;
}
}
The Pojo MyIdGenerator has one public method that accepts two parameters.
However we have also annotated this one with the @Header and @Body
annotation to help Camel know what to bind here from the Message from the
Exchange being processed.
Of course this could be simplified a lot if you for instance just have a
simple id generator. But we wanted to demonstrate that you can use the
Bean Binding annotations anywhere.
public class MySimpleIdGenerator {
public static int generate()
// generate a unique id
return 123;
{
}
}
And finally we just need to remember to have our bean registered in the
Spring Registry:
Example using Groovy
In this example we have an Exchange that has a User object stored in the in
header. This User object has methods to get some user information. We want
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COOKBOOK
to use Groovy to inject an expression that extracts and concats the fullname
of the user into the fullName parameter.
public void doSomething(@Groovy("$request.header['user'].firstName
$request.header['user'].familyName) String fullName, @Body String body) {
// process the inbound message here
}
Groovy supports GStrings that is like a template where we can insert $
placeholders that will be evaluated by Groovy.
BEAN BINDING
The Bean Binding in Camel defines both which methods are invoked and also
how the Message is converted into the parameters of the method when it is
invoked.
Choosing the method to invoke
The binding of a Camel Message to a bean method call can occur in different
ways, order if importance:
• if the message contains the header CamelBeanMethodName then
that method is invoked, converting the body to whatever the
argument is to the method.
◦ From Camel 2.8 onwards you can qualify parameter types to
exact pin-point which method to use when using overloaded
methods with the same name (see further below for more
details).
◦ From Camel 2.9 onwards you can specify parameter values
directly in the method option (see further below for more
details).
• the method name can be specified explicitly in the DSL or when
using POJO Consuming or POJO Producing
• if the bean has a method that is marked with @Handler annotation
then that method is selected
• if the bean can be converted to a Processor using the Type Converter
mechanism then this is used to process the message. This
mechanism is used by the ActiveMQ component to allow any JMS
MessageListener to be invoked directly by Camel without having to
write any integration glue code. You can use the same mechanism to
integrate Camel into any other messaging/remoting frameworks.
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• if the body of the message can be converted to a BeanInvocation
(the default payload used by the ProxyHelper) - then that its used to
invoke the method and pass the arguments
• otherwise the type of the method body is used to try find a method
which matches; an error is thrown if a single method cannot be
chosen unambiguously.
• you can also use Exchange as the parameter itself, but then the
return type must be void.
• if the bean class is private (or package-private), interface methods
will be preferred (from Camel 2.9 onwards) since Camel can't invoke
class methods on such beans
In case where Camel will not be able to choose a method to invoke an
AmbiguousMethodCallException is thrown.
By default the return value is set on the outbound message body.
Parameter binding
When a method have been chosen to be invoked Camel will bind to the
parameters of the method.
The following Camel specific types is automatic binded:
▪ org.apache.camel.Exchange
▪ org.apache.camel.Message
▪ org.apache.camel.CamelContext
▪ org.apache.camel.TypeConverter
▪ org.apache.camel.spi.Registry
▪ java.lang.Exception
So if you declare any of the given type above they will be provided by Camel.
A note on the Exception is that it will bind to the caught exception of the
Exchange. So its often usable if you use a Pojo to handle a given using using
eg an onException route.
What is most interesting is that Camel will also try to bind the body of the
Exchange to the first parameter of the method signature (albeit not of any of
the types above). So if we for instance declare e parameter as: String body
then Camel will bind the IN body to this type. Camel will also automatic type
convert to the given type declared.
Okay lets show some examples.
Below is just a simple method with a body binding. Camel will bind the IN
body to the body parameter and convert it to a String type.
public String doSomething(String body)
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COOKBOOK
And in this sample we got one of the automatic binded type as well, for
instance the Registry that we can use to lookup beans.
public String doSomething(String body, Registry registry)
And we can also use Exchange as well:
public String doSomething(String body, Exchange exchange)
You can have multiple types as well
public String doSomething(String body, Exchange exchange, TypeConverter converter)
And imagine you use a Pojo to handle a given custom exception
InvalidOrderException then we can bind that as well:
Notice we can bind to it even if we use a sub type of java.lang.Exception
as Camel still knows its an exception and thus can bind the caused exception
(if any exists).
public String badOrder(String body, InvalidOrderException invalid)
So what about headers and other stuff? Well now it gets a bit tricky so we
can use annotations to help us, or specify the binding in the method name
option.
See the following sections for more details.
Binding Annotations
You can use the Parameter Binding Annotations to customize how parameter
values are created from the Message
Examples
For example a Bean such as:
public class Bar {
public String doSomething(String body) {
// process the in body and return whatever you want
return "Bye World";
}
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Or the Exchange example. Notice that the return type must be void when
there is only a single parameter:
public class Bar {
public void doSomething(Exchange exchange) {
// process the exchange
exchange.getIn().setBody("Bye World");
}
@Handler
You can mark a method in your bean with the @Handler annotation to
indicate that this method should be used for Bean Binding.
This has the advantage as you do not have to specify the method name in
the Camel route. And thus you do not run into problems when you rename
the method name using an IDE that don't find all references.
public class Bar {
@Handler
public String doSomething(String body) {
// process the in body and return whatever you want
return "Bye World";
}
Parameter binding using method option
Available as of Camel 2.9
Camel uses the following rules to determine if its a parameter value in the
method option
▪ The value is either true or false which denotes a boolean value
▪ The value is a numeric value such as 123 or 7
▪ The value is a String enclosed with either single or double quotes
▪ The value is null which denotes a null value
▪ It can be evaluated using the Simple language, which means you can
use eg body, header.foo and other Simple tokens. Notice the tokens
must be enclosed with ${ }.
Any other value is consider to be a type declaration instead, see next section
about pin pointing types for overloaded methods.
When invoking a Bean you can instruct Camel to invoke a specific method
by providing the method name. For example as shown below:
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COOKBOOK
.bean(OrderService.class, "doSomething")
Here we tell Camel to invoke the doSomething method. How the parameters
is bound is handled by Camel. Now suppose the method has 2 parameters,
and the 2nd parameter is a boolean, where we want to pass in a true value,
such as the method signature below:
public void doSomething(String payload, boolean highPriority) {
...
}
This is now possible in Camel 2.9 onwards:
.bean(OrderService.class, "doSomething(*, true)")
In the example above, we defined the first parameter using the wild card
symbol *, which tells Camel to bind this parameter to any type, and let
Camel figure this out. The 2nd parameter has a fixed value of true. Instead
of the wild card symbol we can instruct Camel to use the message body as
shown:
.bean(OrderService.class, "doSomething(${body}, true)")
The syntax of the parameters is using the Simple expression language so we
have to use ${ } placeholders in the body to refer to the message body.
If you want to pass in a null value, then you can explicit define this in the
method option as shown below:
.to("bean:orderService?method=doSomething(null, true)")
By specifying null as a parameter value, it instructs Camel to force passing
in a null value.
Besides the message body, you can pass in the message headers as a
java.util.Map type, and declare it as follows:
.bean(OrderService.class, "doSomethingWithHeaders(${body}, ${headers})")
You can also pass in other fixed values than boolean values. For example to
pass in an String and integer do as follows:
.bean(MyBean.class, "echo('World', 5)")
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In the example above, we invoke the echo method with two parameters. The
first has the content 'World' (without the quotes). And the 2nd the value of 5.
Camel will automatic type convert the values to the parameter types.
Having the power of the Simple language allows us to bind to message
headers and other values such as:
.bean(OrderService.class, "doSomething(${body}, ${header.high})")
You can also use the OGNL support of the Simple expression language. Now
suppose the message body is an object which has a method named asXml. To
invoke the asXml method we can do as follows:
.bean(OrderService.class, "doSomething(${body.asXml}, ${header.high})")
Instead of using .bean as shown in the examples above, you may want to
use .to instead as shown:
.to("bean:orderService?method=doSomething(${body.asXml}, ${header.high})")
Using type qualifier to pin-point method to use when having
overloaded methods
Available as of Camel 2.8
If you have a Bean which has overloaded methods you can now specify
the parameter types in the method name, so Camel can match the method
you intend to use.
Given the following bean:
Listing 4. MyBean
public static final class MyBean {
public String hello(String name) {
return "Hello " + name;
}
public String hello(String name, @Header("country") String country) {
return "Hello " + name + " you are from " + country;
}
public String times(String name, @Header("times") int times) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < times; i++) {
sb.append(name);
}
return sb.toString();
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COOKBOOK
}
public String times(byte[] data, @Header("times") int times) {
String s = new String(data);
StringBuilder sb = new StringBuilder();
for (int i = 0; i < times; i++) {
sb.append(s);
if (i < times - 1) {
sb.append(",");
}
}
return sb.toString();
}
public String times(String name, int times, char separator) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < times; i++) {
sb.append(name);
if (i < times - 1) {
sb.append(separator);
}
}
return sb.toString();
}
}
Then the MyBean has 2 overloaded methods with the names hello and
times. So if we want to use the method which has 2 parameters we can do
as follows in the Camel route:
Listing 5. Invoke 2 parameter method
from("direct:start")
.bean(MyBean.class, "hello(String,String)")
.to("mock:result");
We can also use a * as wildcard so we can just say we want to execute the
method with 2 parameters we do
Listing 6. Invoke 2 parameter method using wildcard
from("direct:start")
.bean(MyBean.class, "hello(*,*)")
.to("mock:result");
By default Camel will match the type name using the simple name, eg any
leading package name will be disregarded. However if you want to match
using the FQN then specify the FQN type and Camel will leverage that. So if
you have a com.foo.MyOrder and you want to match against the FQN, and
not the simple name "MyOrder" then do as follows:
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.bean(OrderService.class, "doSomething(com.foo.MyOrder)")
Bean Injection
We support the injection of various resources using @EndpointInject. This can
be used to inject
• Endpoint instances which can be used for testing when used with
Mock endpoints; see the Spring Testing for an example.
• ProducerTemplate instances for POJO Producing
• client side proxies for POJO Producing which is a simple approach to
Spring Remoting
Parameter Binding Annotations
Annotations can be used to define an Expression or to extract various
headers, properties or payloads from a Message when invoking a bean
method (see Bean Integration for more detail of how to invoke bean
methods) together with being useful to help disambiguate which method to
invoke.
If no annotations are used then Camel assumes that a single parameter is
the body of the message. Camel will then use the Type Converter mechanism
to convert from the expression value to the actual type of the parameter.
The core annotations are as follows
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Annotation
Meaning
@Body
To bind to an inbound message body
@ExchangeException
To bind to an Exception set on the
exchange (Camel 2.0)
@Header
To bind to an inbound message
header
@Headers
To bind to the Map of the inbound
message headers
@OutHeaders
To bind to the Map of the outbound
message headers
@Property
To bind to a named property on the
exchange
COOKBOOK
Parameter
String
name of
the header
String
name of
the
property
Camel currently only supports either specifying parameter binding
or type per parameter in the method name option. You cannot
specify both at the same time, such as
doSomething(com.foo.MyOrder ${body}, boolean ${header.high})
This may change in the future.
camel-core
The annotations below are all part of camel-core and thus does
not require camel-spring or Spring. These annotations can be
used with the Bean component or when invoking beans in the DSL
@Properties
To bind to the property map on the
exchange
@Handler
Camel 2.0: Not part as a type
parameter but stated in this table
anyway to spread the good word
that we have this annotation in
Camel now. See more at Bean
Binding.
The follow annotations @Headers, @OutHeaders and @Properties binds to
the backing java.util.Map so you can alter the content of these maps
directly, for instance using the put method to add a new entry. See the
OrderService class at Exception Clause for such an example.
Since Camel 2.0, you can use @Header("myHeader") and
@Property("myProperty") instead of @Header(name="myHeader") and
@Property(name="myProperty") as Camel 1.x does.
Example
In this example below we have a @Consume consumer (like message driven)
that consumes JMS messages from the activemq queue. We use the @Header
and @Body parameter binding annotations to bind from the JMSMessage to
the method parameters.
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public class Foo {
@Consume(uri = "activemq:my.queue")
public void doSomething(@Header("JMSCorrelationID") String correlationID, @Body
String body) {
// process the inbound message here
}
}
In the above Camel will extract the value of Message.getJMSCorrelationID(),
then using the Type Converter to adapt the value to the type of the
parameter if required - it will inject the parameter value for the
correlationID parameter. Then the payload of the message will be
converted to a String and injected into the body parameter.
You don't need to use the @Consume annotation; as you could use the
Camel DSL to route to the beans method
Using the DSL to invoke the bean method
Here is another example which does not use POJO Consuming annotations
but instead uses the DSL to route messages to the bean method
public class Foo {
public void doSomething(@Header("JMSCorrelationID") String correlationID, @Body
String body) {
// process the inbound message here
}
}
The routing DSL then looks like this
from("activemq:someQueue").
to("bean:myBean");
Here myBean would be looked up in the Registry (such as JNDI or the Spring
ApplicationContext), then the body of the message would be used to try
figure out what method to call.
If you want to be explicit you can use
from("activemq:someQueue").
to("bean:myBean?methodName=doSomething");
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COOKBOOK
And here we have a nifty example for you to show some great power in
Camel. You can mix and match the annotations with the normal parameters,
so we can have this example with annotations and the Exchange also:
public void doSomething(@Header("user") String user, @Body String body, Exchange
exchange) {
exchange.getIn().setBody(body + "MyBean");
}
Annotation Based Expression Language
You can also use any of the Languages supported in Camel to bind
expressions to method parameters when using Bean Integration. For
example you can use any of these annotations:
Annotation
Description
@Bean
Inject a Bean expression
@BeanShell
Inject a BeanShell expression
@Constant
Inject a Constant expression
@EL
Inject an EL expression
@Groovy
Inject a Groovy expression
@Header
Inject a Header expression
@JavaScript
Inject a JavaScript expression
@MVEL
Inject a Mvel expression
@OGNL
Inject an OGNL expression
@PHP
Inject a PHP expression
@Python
Inject a Python expression
@Ruby
Inject a Ruby expression
@Simple
Inject an Simple expression
@XPath
Inject an XPath expression
@XQuery
Inject an XQuery expression
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Example:
public class Foo {
@MessageDriven(uri = "activemq:my.queue")
public void doSomething(@XPath("/foo/bar/text()") String correlationID, @Body
String body) {
// process the inbound message here
}
}
Advanced example using @Bean
And an example of using the the @Bean binding annotation, where you can
use a Pojo where you can do whatever java code you like:
public class Foo {
@MessageDriven(uri = "activemq:my.queue")
public void doSomething(@Bean("myCorrelationIdGenerator") String correlationID,
@Body String body) {
// process the inbound message here
}
}
And then we can have a spring bean with the id
myCorrelationIdGenerator where we can compute the id.
public class MyIdGenerator {
private UserManager userManager;
public String generate(@Header(name = "user") String user, @Body String payload)
throws Exception {
User user = userManager.lookupUser(user);
String userId = user.getPrimaryId();
String id = userId + generateHashCodeForPayload(payload);
return id;
}
}
The Pojo MyIdGenerator has one public method that accepts two parameters.
However we have also annotated this one with the @Header and @Body
annotation to help Camel know what to bind here from the Message from the
Exchange being processed.
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COOKBOOK
Of course this could be simplified a lot if you for instance just have a
simple id generator. But we wanted to demonstrate that you can use the
Bean Binding annotations anywhere.
public class MySimpleIdGenerator {
public static int generate()
// generate a unique id
return 123;
{
}
}
And finally we just need to remember to have our bean registered in the
Spring Registry:
Example using Groovy
In this example we have an Exchange that has a User object stored in the in
header. This User object has methods to get some user information. We want
to use Groovy to inject an expression that extracts and concats the fullname
of the user into the fullName parameter.
public void doSomething(@Groovy("$request.header['user'].firstName
$request.header['user'].familyName) String fullName, @Body String body) {
// process the inbound message here
}
Groovy supports GStrings that is like a template where we can insert $
placeholders that will be evaluated by Groovy.
@MessageDriven or @Consume
To consume a message you use either the @MessageDriven annotation or
from 1.5.0 the @Consume annotation to mark a particular method of a bean
as being a consumer method. The uri of the annotation defines the Camel
Endpoint to consume from.
e.g. lets invoke the onCheese() method with the String body of the
inbound JMS message from ActiveMQ on the cheese queue; this will use the
Type Converter to convert the JMS ObjectMessage or BytesMessage to a
String - or just use a TextMessage from JMS
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@MessageDriven is @deprecated
@MessageDriven is deprecated in Camel 1.x. You should use
@Consume instead. Its removed in Camel 2.0.
public class Foo {
@Consume(uri="activemq:cheese")
public void onCheese(String name) {
...
}
}
The Bean Binding is then used to convert the inbound Message to the
parameter list used to invoke the method .
What this does is basically create a route that looks kinda like this
from(uri).bean(theBean, "methodName");
Using context option to apply only a certain CamelContext
Available as of Camel 2.0
See the warning above.
You can use the context option to specify which CamelContext the
consumer should only apply for. For example:
@Consume(uri="activemq:cheese", context="camel-1")
public void onCheese(String name) {
The consumer above will only be created for the CamelContext that have the
context id = camel-1. You set this id in the XML tag:
Using an explicit route
If you want to invoke a bean method from many different endpoints or within
different complex routes in different circumstances you can just use the
normal routing DSL or the Spring XML configuration file.
For example
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When using more than one CamelContext
When you use more than 1 CamelContext you might end up with
each of them creating a POJO Consuming.
In Camel 2.0 there is a new option on @Consume that allows you
to specify which CamelContext id/name you want it to apply for.
from(uri).beanRef("myBean", "methodName");
which will then look up in the Registry and find the bean and invoke the
given bean name. (You can omit the method name and have Camel figure
out the right method based on the method annotations and body type).
Use the Bean endpoint
You can always use the bean endpoint
from(uri).to("bean:myBean?method=methodName");
Which approach to use?
Using the @MessageDriven/@Consume annotations are simpler when you
are creating a simple route with a single well defined input URI.
However if you require more complex routes or the same bean method
needs to be invoked from many places then please use the routing DSL as
shown above.
There are two different ways to send messages to any Camel Endpoint
from a POJO
@EndpointInject
To allow sending of messages from POJOs you can use @EndpointInject()
annotation. This will inject either a ProducerTemplate or CamelTemplate so
that the bean can send message exchanges.
e.g. lets send a message to the foo.bar queue in ActiveMQ at some point
public class Foo {
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@EndpointInject(uri="activemq:foo.bar")
ProducerTemplate producer;
public void doSomething() {
if (whatever) {
producer.sendBody("world!");
}
}
}
The downside of this is that your code is now dependent on a Camel API, the
ProducerTemplate. The next section describes how to remove this
Hiding the Camel APIs from your code using @Produce
We recommend Hiding Middleware APIs from your application code so the
next option might be more suitable.
You can add the @Produce annotation to an injection point (a field or
property setter) using a ProducerTemplate or using some interface you use in
your business logic. e.g.
public interface MyListener {
String sayHello(String name);
}
public class MyBean {
@Produce(uri = "activemq:foo")
protected MyListener producer;
public void doSomething() {
// lets send a message
String response = producer.sayHello("James");
}
}
Here Camel will automatically inject a smart client side proxy at the
@Produce annotation - an instance of the MyListener instance. When we
invoke methods on this interface the method call is turned into an object and
using the Camel Spring Remoting mechanism it is sent to the endpoint - in
this case the ActiveMQ endpoint to queue foo; then the caller blocks for a
response.
If you want to make asynchronous message sends then use an @InOnly
annotation on the injection point.
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@RECIPIENTLIST ANNOTATION
As of 1.5.0 we now support the use of @RecipientList on a bean method to
easily create a dynamic Recipient List using a Java method.
Simple Example using @Consume and @RecipientList
package com.acme.foo;
public class RouterBean {
@Consume(uri = "activemq:foo")
@RecipientList
public String[] route(String body) {
return new String[]{"activemq:bar", "activemq:whatnot"};
}
}
For example if the above bean is configured in Spring when using a
element as follows
then a route will be created consuming from the foo queue on the ActiveMQ
component which when a message is received the message will be
forwarded to the endpoints defined by the result of this method call - namely
the bar and whatnot queues.
How it works
The return value of the @RecipientList method is converted to either a
java.util.Collection / java.util.Iterator or array of objects where each element
is converted to an Endpoint or a String, or if you are only going to route to a
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single endpoint then just return either an Endpoint object or an object that
can be converted to a String. So the following methods are all valid
@RecipientList
public String[] route(String body) { ... }
@RecipientList
public List route(String body) { ... }
@RecipientList
public Endpoint route(String body) { ... }
@RecipientList
public Endpoint[] route(String body) { ... }
@RecipientList
public Collection route(String body) { ... }
@RecipientList
public URI route(String body) { ... }
@RecipientList
public URI[] route(String body) { ... }
Then for each endpoint or URI the message is forwarded a separate copy to
that endpoint.
You can then use whatever Java code you wish to figure out what
endpoints to route to; for example you can use the Bean Binding annotations
to inject parts of the message body or headers or use Expression values on
the message.
More Complex Example Using DSL
In this example we will use more complex Bean Binding, plus we will use a
separate route to invoke the Recipient List
public class RouterBean2 {
@RecipientList
public String route(@Header("customerID") String custID String body) {
if (custID == null) return null;
return "activemq:Customers.Orders." + custID;
}
}
public class MyRouteBuilder extends RouteBuilder {
protected void configure() {
from("activemq:Orders.Incoming").recipientList(bean("myRouterBean", "route"));
}
}
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Notice how we are injecting some headers or expressions and using them to
determine the recipients using Recipient List EIP.
See the Bean Integration for more details.
USING EXCHANGE PATTERN ANNOTATIONS
When working with POJO Producing or Spring Remoting you invoke methods
which typically by default are InOut for Request Reply. That is there is an In
message and an Out for the result. Typically invoking this operation will be
synchronous, the caller will block until the server returns a result.
Camel has flexible Exchange Pattern support - so you can also support the
Event Message pattern to use InOnly for asynchronous or one way
operations. These are often called 'fire and forget' like sending a JMS
message but not waiting for any response.
From 1.5 onwards Camel supports annotations for specifying the message
exchange pattern on regular Java methods, classes or interfaces.
Specifying InOnly methods
Typically the default InOut is what most folks want but you can customize to
use InOnly using an annotation.
public interface Foo {
Object someInOutMethod(String input);
String anotherInOutMethod(Cheese input);
@InOnly
void someInOnlyMethod(Document input);
}
The above code shows three methods on an interface; the first two use the
default InOut mechanism but the someInOnlyMethod uses the InOnly
annotation to specify it as being a oneway method call.
Class level annotations
You can also use class level annotations to default all methods in an interface
to some pattern such as
@InOnly
public interface Foo {
void someInOnlyMethod(Document input);
void anotherInOnlyMethod(String input);
}
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Annotations will also be detected on base classes or interfaces. So for
example if you created a client side proxy for
public class MyFoo implements Foo {
...
}
Then the methods inherited from Foo would be InOnly.
Overloading a class level annotation
You can overload a class level annotation on specific methods. A common
use case for this is if you have a class or interface with many InOnly methods
but you want to just annote one or two methods as InOut
@InOnly
public interface Foo {
void someInOnlyMethod(Document input);
void anotherInOnlyMethod(String input);
@InOut
String someInOutMethod(String input);
}
In the above Foo interface the someInOutMethod will be InOut
Using your own annotations
You might want to create your own annotations to represent a group of
different bits of metadata; such as combining synchrony, concurrency and
transaction behaviour.
So you could annotate your annotation with the @Pattern annotation to
default the exchange pattern you wish to use.
For example lets say we want to create our own annotation called
@MyAsyncService
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
// lets add the message exchange pattern to it
@Pattern(ExchangePattern.InOnly)
// lets add some other annotations - maybe transaction behaviour?
public @interface MyAsyncService {
}
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Now we can use this annotation and Camel will figure out the correct
exchange pattern...
public interface Foo {
void someInOnlyMethod(Document input);
void anotherInOnlyMethod(String input);
@MyAsyncService
String someInOutMethod(String input);
}
When writing software these days, its important to try and decouple as much
middleware code from your business logic as possible.
This provides a number of benefits...
• you can choose the right middleware solution for your deployment
and switch at any time
• you don't have to spend a large amount of time learning the specifics
of any particular technology, whether its JMS or JavaSpace or
Hibernate or JPA or iBATIS whatever
For example if you want to implement some kind of message passing,
remoting, reliable load balancing or asynchronous processing in your
application we recommend you use Camel annotations to bind your services
and business logic to Camel Components which means you can then easily
switch between things like
• in JVM messaging with SEDA
• using JMS via ActiveMQ or other JMS providers for reliable load
balancing, grid or publish and subscribe
• for low volume, but easier administration since you're probably
already using a database you could use
◦ Hibernate or JPA to use an entity bean / table as a queue
◦ iBATIS to work with SQL
◦ JDBC for raw SQL access
• use JavaSpace
How to decouple from middleware APIs
The best approach when using remoting is to use Spring Remoting which can
then use any messaging or remoting technology under the covers. When
using Camel's implementation you can then use any of the Camel
Components along with any of the Enterprise Integration Patterns.
Another approach is to bind Java beans to Camel endpoints via the Bean
Integration. For example using POJO Consuming and POJO Producing you can
avoid using any Camel APIs to decouple your code both from middleware
APIs and Camel APIs!
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VISUALISATION
Camel supports the visualisation of your Enterprise Integration Patterns using
the GraphViz DOT files which can either be rendered directly via a suitable
GraphViz tool or turned into HTML, PNG or SVG files via the Camel Maven
Plugin.
Here is a typical example of the kind of thing we can generate
If you click on the actual generated htmlyou will see that you can navigate
from an EIP node to its pattern page, along with getting hover-over tool tips
ec.
How to generate
See Camel Dot Maven Goal or the other maven goals Camel Maven Plugin
For OS X users
If you are using OS X then you can open the DOT file using graphviz which
will then automatically re-render if it changes, so you end up with a real time
graphical representation of the topic and queue hierarchies!
Also if you want to edit the layout a little before adding it to a wiki to
distribute to your team, open the DOT file with OmniGraffle then just edit
away
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BUSINESS ACTIVITY MONITORING
The Camel BAM module provides a Business Activity Monitoring (BAM)
framework for testing business processes across multiple message
exchanges on different Endpoint instances.
For example if you have a simple system which you submit Purchase
Orders into system A and then receive Invoices from system B, you might
want to test that for a specific Purchase Order you receive a matching
Invoice from system B within a specific time period.
How Camel BAM Works
What Camel BAM does is use a Correlation Identifier on an input message to
determine which Process Instance a message belongs to. The process
instance is an entity bean which can maintain state for each Activity (where
an activity typically maps to a single endpoint, such as the receipt of
Purchase orders, or the receipt of Invoices).
You can then add rules which are fired when a message is received on any
activity such as to set time expectations, or to perform real time
reconciliation of values across activities etc.
Simple Example
The following example shows how to perform some time based rules on a
simple business process of 2 activities A and B (which maps to the Purchase
Order and Invoice example above). If you want to experiment with this
scenario you could edit the Test Case which defines the activities and rules,
then tests that they work.
return new ProcessBuilder(jpaTemplate, transactionTemplate) {
public void configure() throws Exception {
// lets define some activities, correlating on an XPath on the message bodies
ActivityBuilder a = activity("seda:a").name("a")
.correlate(xpath("/hello/@id"));
ActivityBuilder b = activity("seda:b").name("b")
.correlate(xpath("/hello/@id"));
// now lets add some rules
b.starts().after(a.completes())
.expectWithin(seconds(1))
.errorIfOver(seconds(errorTimeout)).to("mock:overdue");
}
};
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As you can see in the above example, we define two activities first, then we
define rules on when we expect the activities on an individual process
instance to complete by along with the time at which we should assume
there is an error. The ProcessBuilder is-a RouteBuilder and can be added to
any CamelContext
Complete Example
For a complete example please see the BAM Example which is part of the
standard Camel Examples
Use Cases
In the world of finance a common requirement is tracking financial trades.
Often a trader will submit a Front Office Trade which then flows through the
Middle Office and Back Office through various systems to settle the trade so
that money is exchanged. You may wish to add tests that front and back
office trades match up within a time period; if they don't match or a back
office trade does not arrive within a required amount of time, you might want
to fire off an alarm.
EXTRACT TRANSFORM LOAD (ETL)
The ETL (Extract, Transform, Load) is a mechanism for loading data into
systems or databases using some kind of Data Format from a variety of
sources; often files then using Pipes and Filters, Message Translator and
possible other Enterprise Integration Patterns.
So you could query data from various Camel Components such as File,
HTTP or JPA, perform multiple patterns such as Splitter or Message Translator
then send the messages to some other Component.
To show how this all fits together, try the ETL Example
MOCK COMPONENT
Testing of distributed and asynchronous processing is notoriously difficult.
The Mock, Test and DataSet endpoints work great with the Camel Testing
Framework to simplify your unit and integration testing using Enterprise
Integration Patterns and Camel's large range of Components together with
the powerful Bean Integration.
The Mock component provides a powerful declarative testing mechanism,
which is similar to jMock in that it allows declarative expectations to be
created on any Mock endpoint before a test begins. Then the test is run,
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which typically fires messages to one or more endpoints, and finally the
expectations can be asserted in a test case to ensure the system worked as
expected.
This allows you to test various things like:
• The correct number of messages are received on each endpoint,
• The correct payloads are received, in the right order,
• Messages arrive on an endpoint in order, using some Expression to
create an order testing function,
• Messages arrive match some kind of Predicate such as that specific
headers have certain values, or that parts of the messages match
some predicate, such as by evaluating an XPath or XQuery
Expression.
Note that there is also the Test endpoint which is a Mock endpoint, but which
uses a second endpoint to provide the list of expected message bodies and
automatically sets up the Mock endpoint assertions. In other words, it's a
Mock endpoint that automatically sets up its assertions from some sample
messages in a File or database, for example.
URI format
mock:someName[?options]
Where someName can be any string that uniquely identifies the endpoint.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Option
Default
Description
reportGroup
null
A size to use a throughput logger for reporting
Simple Example
Here's a simple example of Mock endpoint in use. First, the endpoint is
resolved on the context. Then we set an expectation, and then, after the test
has run, we assert that our expectations have been met.
MockEndpoint resultEndpoint = context.resolveEndpoint("mock:foo", MockEndpoint.class);
resultEndpoint.expectedMessageCount(2);
// send some messages
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...
// now lets assert that the mock:foo endpoint received 2 messages
resultEndpoint.assertIsSatisfied();
You typically always call the assertIsSatisfied() method to test that the
expectations were met after running a test.
Camel will by default wait 10 seconds when the assertIsSatisfied() is
invoked. This can be configured by setting the setResultWaitTime(millis)
method.
When the assertion is satisfied then Camel will stop waiting and continue
from the assertIsSatisfied method. That means if a new message arrives
on the mock endpoint, just a bit later, that arrival will not affect the outcome
of the assertion. Suppose you do want to test that no new messages arrives
after a period thereafter, then you can do that by setting the
setAssertPeriod method.
Using assertPeriod
Available as of Camel 2.7
When the assertion is satisfied then Camel will stop waiting and continue
from the assertIsSatisfied method. That means if a new message arrives
on the mock endpoint, just a bit later, that arrival will not affect the outcome
of the assertion. Suppose you do want to test that no new messages arrives
after a period thereafter, then you can do that by setting the
setAssertPeriod method, for example:
MockEndpoint resultEndpoint = context.resolveEndpoint("mock:foo", MockEndpoint.class);
resultEndpoint.setAssertPeriod(5000);
resultEndpoint.expectedMessageCount(2);
// send some messages
...
// now lets assert that the mock:foo endpoint received 2 messages
resultEndpoint.assertIsSatisfied();
Setting expectations
You can see from the javadoc of MockEndpoint the various helper methods
you can use to set expectations. The main methods are as follows:
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Method
Description
expectedMessageCount(int)
To define the expected message count on the endpoint.
COOKBOOK
expectedMinimumMessageCount(int)
To define the minimum number of expected messages on the endpoint.
expectedBodiesReceived(...)
To define the expected bodies that should be received (in order).
expectedHeaderReceived(...)
To define the expected header that should be received
expectsAscending(Expression)
To add an expectation that messages are received in order, using the given Expression to compare
messages.
expectsDescending(Expression)
To add an expectation that messages are received in order, using the given Expression to compare
messages.
expectsNoDuplicates(Expression)
To add an expectation that no duplicate messages are received; using an Expression to calculate a
unique identifier for each message. This could be something like the JMSMessageID if using JMS, or some
unique reference number within the message.
Here's another example:
resultEndpoint.expectedBodiesReceived("firstMessageBody", "secondMessageBody",
"thirdMessageBody");
Adding expectations to specific messages
In addition, you can use the message(int messageIndex) method to add
assertions about a specific message that is received.
For example, to add expectations of the headers or body of the first
message (using zero-based indexing like java.util.List), you can use the
following code:
resultEndpoint.message(0).header("foo").isEqualTo("bar");
There are some examples of the Mock endpoint in use in the camel-core
processor tests.
Mocking existing endpoints
Available as of Camel 2.7
Camel now allows you to automatic mock existing endpoints in your Camel
routes.
Suppose you have the given route below:
Listing 7. Route
@Override
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
from("direct:start").to("direct:foo").to("log:foo").to("mock:result");
from("direct:foo").transform(constant("Bye World"));
}
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How it works
Important: The endpoints are still in action, what happens is that a
Mock endpoint is injected and receives the message first, it then
delegate the message to the target endpoint. You can view this as a
kind of intercept and delegate or endpoint listener.
};
}
You can then use the adviceWith feature in Camel to mock all the endpoints
in a given route from your unit test, as shown below:
Listing 8. adviceWith mocking all endpoints
public void testAdvisedMockEndpoints() throws Exception {
// advice the first route using the inlined AdviceWith route builder
// which has extended capabilities than the regular route builder
context.getRouteDefinitions().get(0).adviceWith(context, new
AdviceWithRouteBuilder() {
@Override
public void configure() throws Exception {
// mock all endpoints
mockEndpoints();
}
});
getMockEndpoint("mock:direct:start").expectedBodiesReceived("Hello World");
getMockEndpoint("mock:direct:foo").expectedBodiesReceived("Hello World");
getMockEndpoint("mock:log:foo").expectedBodiesReceived("Bye World");
getMockEndpoint("mock:result").expectedBodiesReceived("Bye World");
template.sendBody("direct:start", "Hello World");
assertMockEndpointsSatisfied();
// additional test to ensure correct endpoints in registry
assertNotNull(context.hasEndpoint("direct:start"));
assertNotNull(context.hasEndpoint("direct:foo"));
assertNotNull(context.hasEndpoint("log:foo"));
assertNotNull(context.hasEndpoint("mock:result"));
// all the endpoints was mocked
assertNotNull(context.hasEndpoint("mock:direct:start"));
assertNotNull(context.hasEndpoint("mock:direct:foo"));
assertNotNull(context.hasEndpoint("mock:log:foo"));
}
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Notice that the mock endpoints is given the uri mock:, for
example mock:direct:foo. Camel logs at INFO level the endpoints being
mocked:
INFO
Adviced endpoint [direct://foo] with mock endpoint [mock:direct:foo]
Its also possible to only mock certain endpoints using a pattern. For example
to mock all log endpoints you do as shown:
Listing 9. adviceWith mocking only log endpoints using a pattern
public void testAdvisedMockEndpointsWithPattern() throws Exception {
// advice the first route using the inlined AdviceWith route builder
// which has extended capabilities than the regular route builder
context.getRouteDefinitions().get(0).adviceWith(context, new
AdviceWithRouteBuilder() {
@Override
public void configure() throws Exception {
// mock only log endpoints
mockEndpoints("log*");
}
});
// now we can refer to log:foo as a mock and set our expectations
getMockEndpoint("mock:log:foo").expectedBodiesReceived("Bye World");
getMockEndpoint("mock:result").expectedBodiesReceived("Bye World");
template.sendBody("direct:start", "Hello World");
assertMockEndpointsSatisfied();
// additional test to ensure correct endpoints in registry
assertNotNull(context.hasEndpoint("direct:start"));
assertNotNull(context.hasEndpoint("direct:foo"));
assertNotNull(context.hasEndpoint("log:foo"));
assertNotNull(context.hasEndpoint("mock:result"));
// only the log:foo endpoint was mocked
assertNotNull(context.hasEndpoint("mock:log:foo"));
assertNull(context.hasEndpoint("mock:direct:start"));
assertNull(context.hasEndpoint("mock:direct:foo"));
}
The pattern supported can be a wildcard or a regular expression. See more
details about this at Intercept as its the same matching function used by
Camel.
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Mocked endpoints are without parameters
Endpoints which are mocked will have their parameters stripped off.
For example the endpoint "log:foo?showAll=true" will be mocked to
the following endpoint "mock:log:foo". Notice the parameters has
been removed.
Mind that mocking endpoints causes the messages to be copied
when they arrive on the mock.
That means Camel will use more memory. This may not be suitable
when you send in a lot of messages.
Mocking existing endpoints using the camel-test
component
Instead of using the adviceWith to instruct Camel to mock endpoints, you
can easily enable this behavior when using the camel-test Test Kit.
The same route can be tested as follows. Notice that we return "*" from the
isMockEndpoints method, which tells Camel to mock all endpoints.
If you only want to mock all log endpoints you can return "log*" instead.
Listing 10. isMockEndpoints using camel-test kit
public class IsMockEndpointsJUnit4Test extends CamelTestSupport {
@Override
public String isMockEndpoints() {
// override this method and return the pattern for which endpoints to mock.
// use * to indicate all
return "*";
}
@Test
public void testMockAllEndpoints() throws Exception {
// notice we have automatic mocked all endpoints and the name of the
endpoints is "mock:uri"
getMockEndpoint("mock:direct:start").expectedBodiesReceived("Hello World");
getMockEndpoint("mock:direct:foo").expectedBodiesReceived("Hello World");
getMockEndpoint("mock:log:foo").expectedBodiesReceived("Bye World");
getMockEndpoint("mock:result").expectedBodiesReceived("Bye World");
template.sendBody("direct:start", "Hello World");
assertMockEndpointsSatisfied();
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// additional test to ensure correct endpoints in registry
assertNotNull(context.hasEndpoint("direct:start"));
assertNotNull(context.hasEndpoint("direct:foo"));
assertNotNull(context.hasEndpoint("log:foo"));
assertNotNull(context.hasEndpoint("mock:result"));
// all the endpoints was mocked
assertNotNull(context.hasEndpoint("mock:direct:start"));
assertNotNull(context.hasEndpoint("mock:direct:foo"));
assertNotNull(context.hasEndpoint("mock:log:foo"));
}
@Override
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
from("direct:start").to("direct:foo").to("log:foo").to("mock:result");
from("direct:foo").transform(constant("Bye World"));
}
};
}
}
Mocking existing endpoints with XML DSL
If you do not use the camel-test component for unit testing (as shown
above) you can use a different approach when using XML files for routes.
The solution is to create a new XML file used by the unit test and then
include the intended XML file which has the route you want to test.
Suppose we have the route in the camel-route.xml file:
Listing 11. camel-route.xml
Bye World
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Then we create a new XML file as follows, where we include the camelroute.xml file and define a spring bean with the class
org.apache.camel.impl.InterceptSendToMockEndpointStrategy which
tells Camel to mock all endpoints:
Listing 12. test-camel-route.xml
Then in your unit test you load the new XML file (test-camel-route.xml)
instead of camel-route.xml.
To only mock all Log endpoints you can define the pattern in the
constructor for the bean:
Testing with arrival times
Available as of Camel 2.7
The Mock endpoint stores the arrival time of the message as a property on
the Exchange.
Date time = exchange.getProperty(Exchange.RECEIVED_TIMESTAMP, Date.class);
You can use this information to know when the message arrived on the mock.
But it also provides foundation to know the time interval between the
previous and next message arrived on the mock. You can use this to set
expectations using the arrives DSL on the Mock endpoint.
For example to say that the first message should arrive between 0-2
seconds before the next you can do:
mock.message(0).arrives().noLaterThan(2).seconds().beforeNext();
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You can also define this as that 2nd message (0 index based) should arrive
no later than 0-2 seconds after the previous:
mock.message(1).arrives().noLaterThan(2).seconds().afterPrevious();
You can also use between to set a lower bound. For example suppose that it
should be between 1-4 seconds:
mock.message(1).arrives().between(1, 4).seconds().afterPrevious();
You can also set the expectation on all messages, for example to say that the
gap between them should be at most 1 second:
mock.allMessages().arrives().noLaterThan(1).seconds().beforeNext();
See Also
•
•
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
Spring Testing
Testing
TESTING
Testing is a crucial activity in any piece of software development or
integration. Typically Camel Riders use various different technologies wired
together in a variety of patterns with different expression languages together
with different forms of Bean Integration and Dependency Injection so its very
easy for things to go wrong!
. Testing is the crucial weapon to ensure that
things work as you would expect.
Camel is a Java library so you can easily wire up tests in whatever unit
testing framework you use (JUnit 3.x, 4.x or TestNG). However the Camel
project has tried to make the testing of Camel as easy and powerful as
possible so we have introduced the following features.
Testing mechanisms
The following mechanisms are supported
Name
Description
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time units
In the example above we use seconds as the time unit, but Camel
offers milliseconds, and minutes as well.
Camel
Test
is a library letting you easily create Camel test cases using a
single Java class for all your configuration and routing without
using Spring or Guice for Dependency Injection which does not
require an in depth knowledge of Spring+SpringTest or Guice
Spring
Testing
uses Spring Test together with either XML or Java Config to
dependency inject your test classes
Guice
uses Guice to dependency inject your test classes
In all approaches the test classes look pretty much the same in that they all
reuse the Camel binding and injection annotations.
Camel Test Example
Here is the Camel Test example.
public class FilterTest extends CamelTestSupport {
@EndpointInject(uri = "mock:result")
protected MockEndpoint resultEndpoint;
@Produce(uri = "direct:start")
protected ProducerTemplate template;
@Test
public void testSendMatchingMessage() throws Exception {
String expectedBody = "";
resultEndpoint.expectedBodiesReceived(expectedBody);
template.sendBodyAndHeader(expectedBody, "foo", "bar");
resultEndpoint.assertIsSatisfied();
}
@Test
public void testSendNotMatchingMessage() throws Exception {
resultEndpoint.expectedMessageCount(0);
template.sendBodyAndHeader("", "foo", "notMatchedHeaderValue");
resultEndpoint.assertIsSatisfied();
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}
@Override
protected RouteBuilder createRouteBuilder() {
return new RouteBuilder() {
public void configure() {
from("direct:start").filter(header("foo").isEqualTo("bar")).to("mock:result");
}
};
}
}
Notice how it derives from the Camel helper class CamelTestSupport but
has no Spring or Guice dependency injection configuration but instead
overrides the createRouteBuilder() method.
Spring Test with XML Config Example
Here is the Spring Testing example using XML Config.
@ContextConfiguration
public class FilterTest extends AbstractJUnit38SpringContextTests {
@EndpointInject(uri = "mock:result")
protected MockEndpoint resultEndpoint;
@Produce(uri = "direct:start")
protected ProducerTemplate template;
@DirtiesContext
public void testSendMatchingMessage() throws Exception {
String expectedBody = "";
resultEndpoint.expectedBodiesReceived(expectedBody);
template.sendBodyAndHeader(expectedBody, "foo", "bar");
resultEndpoint.assertIsSatisfied();
}
@DirtiesContext
public void testSendNotMatchingMessage() throws Exception {
resultEndpoint.expectedMessageCount(0);
template.sendBodyAndHeader("", "foo", "notMatchedHeaderValue");
resultEndpoint.assertIsSatisfied();
}
}
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Notice that we use @DirtiesContext on the test methods to force Spring
Testing to automatically reload the CamelContext after each test method this ensures that the tests don't clash with each other (e.g. one test method
sending to an endpoint that is then reused in another test method).
Also notice the use of @ContextConfiguration to indicate that by default
we should look for the FilterTest-context.xml on the classpath to configure
the test case which looks like this
$foo = 'bar'
Spring Test with Java Config Example
Here is the Spring Testing example using Java Config. For more information
see Spring Java Config.
@ContextConfiguration(
locations =
"org.apache.camel.spring.javaconfig.patterns.FilterTest$ContextConfig",
loader = JavaConfigContextLoader.class)
public class FilterTest extends AbstractJUnit4SpringContextTests {
@EndpointInject(uri = "mock:result")
protected MockEndpoint resultEndpoint;
@Produce(uri = "direct:start")
protected ProducerTemplate template;
@DirtiesContext
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@Test
public void testSendMatchingMessage() throws Exception {
String expectedBody = "";
resultEndpoint.expectedBodiesReceived(expectedBody);
template.sendBodyAndHeader(expectedBody, "foo", "bar");
resultEndpoint.assertIsSatisfied();
}
@DirtiesContext
@Test
public void testSendNotMatchingMessage() throws Exception {
resultEndpoint.expectedMessageCount(0);
template.sendBodyAndHeader("", "foo", "notMatchedHeaderValue");
resultEndpoint.assertIsSatisfied();
}
@Configuration
public static class ContextConfig extends SingleRouteCamelConfiguration {
@Bean
public RouteBuilder route() {
return new RouteBuilder() {
public void configure() {
from("direct:start").filter(header("foo").isEqualTo("bar")).to("mock:result");
}
};
}
}
}
This is similar to the XML Config example above except that there is no XML
file and instead the nested ContextConfig class does all of the
configuration; so your entire test case is contained in a single Java class. We
currently have to reference by class name this class in the
@ContextConfiguration which is a bit ugly. Please vote for SJC-238 to
address this and make Spring Test work more cleanly with Spring JavaConfig.
Its totally optional but for the ContextConfig implementation we derive
from SingleRouteCamelConfiguration which is a helper Spring Java Config
class which will configure the CamelContext for us and then register the
RouteBuilder we create.
Testing endpoints
Camel provides a number of endpoints which can make testing easier.
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Name
Description
DataSet
For load & soak testing this endpoint provides a way to create
huge numbers of messages for sending to Components and
asserting that they are consumed correctly
Mock
For testing routes and mediation rules using mocks and allowing
assertions to be added to an endpoint
Test
Creates a Mock endpoint which expects to receive all the
message bodies that could be polled from the given underlying
endpoint
The main endpoint is the Mock endpoint which allows expectations to be
added to different endpoints; you can then run your tests and assert that
your expectations are met at the end.
Stubbing out physical transport technologies
If you wish to test out a route but want to avoid actually using a real physical
transport (for example to unit test a transformation route rather than
performing a full integration test) then the following endpoints can be useful.
Name
Description
Direct
Direct invocation of the consumer from the producer so that
single threaded (non-SEDA) in VM invocation is performed which
can be useful to mock out physical transports
SEDA
Delivers messages asynchonously to consumers via a
java.util.concurrent.BlockingQueue which is good for testing
asynchronous transports
Testing existing routes
Camel provides some features to aid during testing of existing routes where
you cannot or will not use Mock etc. For example you may have a production
ready route which you want to test with some 3rd party API which sends
messages into this route.
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Name
Description
NotifyBuilder
Allows you to be notified when a certain condition has
occurred. For example when the route has completed 5
messages. You can build complex expressions to match
your criteria when to be notified.
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AdviceWith
Allows you to advice or enhance an existing route using a
RouteBuilder style. For example you can add interceptors
to intercept sending outgoing messages to assert those
messages are as expected.
CAMEL TEST
As a simple alternative to using Spring Testing or Guice the camel-test
module was introduced into the Camel 2.0 trunk so you can perform powerful
Testing of your Enterprise Integration Patterns easily.
Adding to your pom.xml
To get started using Camel Test you will need to add an entry to your
pom.xml
JUnit
org.apache.camelcamel-test${camel-version}test
TestNG
Available as of Camel 2.8
org.apache.camelcamel-testng${camel-version}test
You might also want to add slf4j and log4j to ensure nice logging messages
(and maybe adding a log4j.properties file into your src/test/resources
directory).
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The camel-test JAR is using JUnit. There is an alternative cameltestng JAR (Camel 2.8 onwards) using the TestNG test framework.
org.slf4jslf4j-log4j12testlog4jlog4jtest
Writing your test
You firstly need to derive from the class CamelTestSupport and typically
you will need to override the createRouteBuilder() method to create routes
to be tested.
Here is an example.
public class FilterTest extends CamelTestSupport {
@EndpointInject(uri = "mock:result")
protected MockEndpoint resultEndpoint;
@Produce(uri = "direct:start")
protected ProducerTemplate template;
@Test
public void testSendMatchingMessage() throws Exception {
String expectedBody = "";
resultEndpoint.expectedBodiesReceived(expectedBody);
template.sendBodyAndHeader(expectedBody, "foo", "bar");
resultEndpoint.assertIsSatisfied();
}
@Test
public void testSendNotMatchingMessage() throws Exception {
resultEndpoint.expectedMessageCount(0);
template.sendBodyAndHeader("", "foo", "notMatchedHeaderValue");
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resultEndpoint.assertIsSatisfied();
}
@Override
protected RouteBuilder createRouteBuilder() {
return new RouteBuilder() {
public void configure() {
from("direct:start").filter(header("foo").isEqualTo("bar")).to("mock:result");
}
};
}
}
Notice how you can use the various Camel binding and injection annotations
to inject individual Endpoint objects - particularly the Mock endpoints which
are very useful for Testing. Also you can inject producer objects such as
ProducerTemplate or some application code interface for sending messages
or invoking services.
JNDI
Camel uses a Registry to allow you to configure Component or Endpoint
instances or Beans used in your routes. If you are not using Spring or [OSGi]
then JNDI is used as the default registry implementation.
So you will also need to create a jndi.properties file in your src/test/
resources directory so that there is a default registry available to initialise
the CamelContext.
Here is an example jndi.properties file
java.naming.factory.initial = org.apache.camel.util.jndi.CamelInitialContextFactory
Dynamically assigning ports
Available as of Camel 2.7
Tests that use port numbers will fail if that port is already on use.
AvailablePortFinder provides methods for finding unused port numbers at
runtime.
// Get the next available port number starting from the default starting port of 1024
int port1 = AvailablePortFinder.getNextAvailable();
/*
* Get another port. Note that just getting a port number does not reserve it so
* we look starting one past the last port number we got.
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*/
int port2 = AvailablePortFinder.getNextAvailable(port1 + 1);
Setup CamelContext once per class, or per every test method
Available as of Camel 2.8
The Camel Test kit will by default setup and shutdown CamelContext per
every test method in your test class. So for example if you have 3 test
methods, then CamelContext is started and shutdown after each test, that is
3 times.
You may want to do this once, to share the CamelContext between test
methods, to speedup unit testing. This requires to use JUnit 4! In your unit
test method you have to extend the
org.apache.camel.test.junit4.CamelTestSupport or the
org.apache.camel.test.junit4.CamelSpringTestSupport test class and
override the isCreateCamelContextPerClass method and return true as
shown in the following example:
Listing 13. Setup CamelContext once per class
public class FilterCreateCamelContextPerClassTest extends CamelTestSupport {
@EndpointInject(uri = "mock:result")
protected MockEndpoint resultEndpoint;
@Produce(uri = "direct:start")
protected ProducerTemplate template;
@Override
public boolean isCreateCamelContextPerClass() {
// we override this method and return true, to tell Camel test-kit that
// it should only create CamelContext once (per class), so we will
// re-use the CamelContext between each test method in this class
return true;
}
@Test
public void testSendMatchingMessage() throws Exception {
String expectedBody = "";
resultEndpoint.expectedBodiesReceived(expectedBody);
template.sendBodyAndHeader(expectedBody, "foo", "bar");
resultEndpoint.assertIsSatisfied();
}
@Test
public void testSendNotMatchingMessage() throws Exception {
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TestNG
This feature is also supported in camel-testng
Beware
When using this the CamelContext will keep state between tests, so
have that in mind. So if your unit tests start to fail for no apparent
reason, it could be due this fact. So use this feature with a bit of
care.
resultEndpoint.expectedMessageCount(0);
template.sendBodyAndHeader("", "foo", "notMatchedHeaderValue");
resultEndpoint.assertIsSatisfied();
}
@Override
protected RouteBuilder createRouteBuilder() {
return new RouteBuilder() {
public void configure() {
from("direct:start").filter(header("foo").isEqualTo("bar")).to("mock:result");
}
};
}
}
See Also
• Testing
• Mock
• Test
SPRING TESTING
Testing is a crucial part of any development or integration work. The Spring
Framework offers a number of features that makes it easy to test while using
Spring for Inversion of Control which works with JUnit 3.x, JUnit 4.x or TestNG.
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We can reuse Spring for IoC and the Camel Mock and Test endpoints to
create sophisticated integration tests that are easy to run and debug inside
your IDE.
For example here is a simple unit test
import
import
import
import
import
org.apache.camel.CamelContext;
org.apache.camel.component.mock.MockEndpoint;
org.springframework.beans.factory.annotation.Autowired;
org.springframework.test.context.ContextConfiguration;
org.springframework.test.context.junit38.AbstractJUnit38SpringContextTests;
@ContextConfiguration
public class MyCamelTest extends AbstractJUnit38SpringContextTests {
@Autowired
protected CamelContext camelContext;
public void testMocksAreValid() throws Exception {
MockEndpoint.assertIsSatisfied(camelContext);
}
}
This test will load a Spring XML configuration file called MyCamelTestcontext.xml from the classpath in the same package structure as the
MyCamelTest class and initialize it along with any Camel routes we define
inside it, then inject the CamelContext instance into our test case.
For instance, like this maven folder layout:
src/main/java/com/mycompany/MyCamelTest.class
src/main/resources/com/mycompany/MyCamelTest-context.xml
You can overload the method createApplicationContext to provide the
Spring ApplicationContext that isn't following the above default. For instance:
protected AbstractXmlApplicationContext createApplicationContext() {
return new ClassPathXmlApplicationContext("/config/MySpringConfig.xml");
}
Then the test method will then run which invokes the
MockEndpoint.assertIsSatisfied(camelContext) method which asserts that all
of the Mock and Test endpoints have their expectations met.
xml}
Spring Test with Java Config Example
You can completely avoid using an XML configuration file by using Spring
Java Config.
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Here is an example using Java Config.
@ContextConfiguration(
locations =
"org.apache.camel.spring.javaconfig.patterns.FilterTest$ContextConfig",
loader = JavaConfigContextLoader.class)
public class FilterTest extends AbstractJUnit4SpringContextTests {
@EndpointInject(uri = "mock:result")
protected MockEndpoint resultEndpoint;
@Produce(uri = "direct:start")
protected ProducerTemplate template;
@DirtiesContext
@Test
public void testSendMatchingMessage() throws Exception {
String expectedBody = "";
resultEndpoint.expectedBodiesReceived(expectedBody);
template.sendBodyAndHeader(expectedBody, "foo", "bar");
resultEndpoint.assertIsSatisfied();
}
@DirtiesContext
@Test
public void testSendNotMatchingMessage() throws Exception {
resultEndpoint.expectedMessageCount(0);
template.sendBodyAndHeader("", "foo", "notMatchedHeaderValue");
resultEndpoint.assertIsSatisfied();
}
@Configuration
public static class ContextConfig extends SingleRouteCamelConfiguration {
@Bean
public RouteBuilder route() {
return new RouteBuilder() {
public void configure() {
from("direct:start").filter(header("foo").isEqualTo("bar")).to("mock:result");
}
};
}
}
}
This is similar to the XML Config example above except that there is no XML
file and instead the nested ContextConfig class does all of the
configuration; so your entire test case is contained in a single Java class. We
currently have to reference by class name this class in the
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@ContextConfiguration which is a bit ugly. Please vote for SJC-238 to
address this and make Spring Test work more cleanly with Spring JavaConfig.
Adding more Mock expectations
If you wish to programmatically add any new assertions to your test you can
easily do so with the following. Notice how we use @EndpointInject to inject a
Camel endpoint into our code then the Mock API to add an expectation on a
specific message.
@ContextConfiguration
public class MyCamelTest extends AbstractJUnit38SpringContextTests {
@Autowired
protected CamelContext camelContext;
@EndpointInject(uri = "mock:foo")
protected MockEndpoint foo;
public void testMocksAreValid() throws Exception {
// lets add more expectations
foo.message(0).header("bar").isEqualTo("ABC");
MockEndpoint.assertIsSatisfied(camelContext);
}
}
Further processing the received messages
Sometimes once a Mock endpoint has received some messages you want to
then process them further to add further assertions that your test case
worked as you expect.
So you can then process the received message exchanges if you like...
@ContextConfiguration
public class MyCamelTest extends AbstractJUnit38SpringContextTests {
@Autowired
protected CamelContext camelContext;
@EndpointInject(uri = "mock:foo")
protected MockEndpoint foo;
public void testMocksAreValid() throws Exception {
// lets add more expectations...
MockEndpoint.assertIsSatisfied(camelContext);
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// now lets do some further assertions
List list = foo.getReceivedExchanges();
for (Exchange exchange : list) {
Message in = exchange.getIn();
...
}
}
}
Sending and receiving messages
It might be that the Enterprise Integration Patterns you have defined in either
Spring XML or using the Java DSL do all of the sending and receiving and you
might just work with the Mock endpoints as described above. However
sometimes in a test case its useful to explicitly send or receive messages
directly.
To send or receive messages you should use the Bean Integration
mechanism. For example to send messages inject a ProducerTemplate using
the @EndpointInject annotation then call the various send methods on this
object to send a message to an endpoint. To consume messages use the
@MessageDriven annotation on a method to have the method invoked when
a message is received.
public class Foo {
@EndpointInject(uri="activemq:foo.bar")
ProducerTemplate producer;
public void doSomething() {
// lets send a message!
producer.sendBody("world!");
}
// lets consume messages from the 'cheese' queue
@MessageDriven(uri="activemq:cheese")
public void onCheese(String name) {
...
}
}
See Also
• a real example test case using Mock and Spring along with its Spring
XML
• Bean Integration
• Mock endpoint
• Test endpoint
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CAMEL GUICE
As of 1.5 we now have support for Google Guice as a dependency injection
framework. To use it just be dependent on camel-guice.jar which also
depends on the following jars.
Dependency Injecting Camel with Guice
The GuiceCamelContext is designed to work nicely inside Guice. You then
need to bind it using some Guice Module.
The camel-guice library comes with a number of reusable Guice Modules
you can use if you wish - or you can bind the GuiceCamelContext yourself in
your own module.
• CamelModule is the base module which binds the
GuiceCamelContext but leaves it up you to bind the RouteBuilder
instances
• CamelModuleWithRouteTypes extends CamelModule so that in the
constructor of the module you specify the RouteBuilder classes or
instances to use
• CamelModuleWithMatchingRoutes extends CamelModule so that all
bound RouteBuilder instances will be injected into the CamelContext
or you can supply an optional Matcher to find RouteBuilder instances
matching some kind of predicate.
So you can specify the exact RouteBuilder instances you want
Injector injector = Guice.createInjector(new
CamelModuleWithRouteTypes(MyRouteBuilder.class, AnotherRouteBuilder.class));
// if required you can lookup the CamelContext
CamelContext camelContext = injector.getInstance(CamelContext.class);
Or inject them all
Injector injector = Guice.createInjector(new CamelModuleWithRouteTypes());
// if required you can lookup the CamelContext
CamelContext camelContext = injector.getInstance(CamelContext.class);
You can then use Guice in the usual way to inject the route instances or any
other dependent objects.
Bootstrapping with JNDI
A common pattern used in J2EE is to bootstrap your application or root
objects by looking them up in JNDI. This has long been the approach when
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working with JMS for example - looking up the JMS ConnectionFactory in JNDI
for example.
You can follow a similar pattern with Guice using the GuiceyFruit JNDI
Provider which lets you bootstrap Guice from a jndi.properties file which
can include the Guice Modules to create along with environment specific
properties you can inject into your modules and objects.
If the jndi.properties is conflict with other component, you can specify
the jndi properties file name in the Guice Main with option -j or -jndiProperties
with the properties file location to let Guice Main to load right jndi properties
file.
Configuring Component, Endpoint or RouteBuilder instances
You can use Guice to dependency inject whatever objects you need to create,
be it an Endpoint, Component, RouteBuilder or arbitrary bean used within a
route.
The easiest way to do this is to create your own Guice Module class which
extends one of the above module classes and add a provider method for
each object you wish to create. A provider method is annotated with
@Provides as follows
public class MyModule extends CamelModuleWithMatchingRoutes {
@Provides
@JndiBind("jms")
JmsComponent jms(@Named("activemq.brokerURL") String brokerUrl) {
return JmsComponent.jmsComponent(new ActiveMQConnectionFactory(brokerUrl));
}
}
You can optionally annotate the method with @JndiBind to bind the object to
JNDI at some name if the object is a component, endpoint or bean you wish
to refer to by name in your routes.
You can inject any environment specific properties (such as URLs, machine
names, usernames/passwords and so forth) from the jndi.properties file
easily using the @Named annotation as shown above. This allows most of
your configuration to be in Java code which is typesafe and easily
refactorable - then leaving some properties to be environment specific (the
jndi.properties file) which you can then change based on development,
testing, production etc.
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Creating multiple RouteBuilder instances per type
It is sometimes useful to create multiple instances of a particular
RouteBuilder with different configurations.
To do this just create multiple provider methods for each configuration; or
create a single provider method that returns a collection of RouteBuilder
instances.
For example
import org.apache.camel.guice.CamelModuleWithMatchingRoutes;
import com.google.common.collect.Lists;
public class MyModule extends CamelModuleWithMatchingRoutes {
@Provides
@JndiBind("foo")
Collection foo(@Named("fooUrl") String fooUrl) {
return Lists.newArrayList(new MyRouteBuilder(fooUrl), new
MyRouteBuilder("activemq:CheeseQueue"));
}
}
See Also
• there are a number of Examples you can look at to see Guice and
Camel being used such as Guice JMS Example
• Guice Maven Plugin for running your Guice based routes via Maven
TEMPLATING
When you are testing distributed systems its a very common requirement to
have to stub out certain external systems with some stub so that you can
test other parts of the system until a specific system is available or written
etc.
A great way to do this is using some kind of Template system to generate
responses to requests generating a dynamic message using a mostly-static
body.
There are a number of templating components included in the Camel
distribution you could use
• FreeMarker
• StringTemplate
• Velocity
• XQuery
• XSLT
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or the following external Camel components
• Scalate
Example
Here's a simple example showing how we can respond to InOut requests on
the My.Queue queue on ActiveMQ with a template generated response. The
reply would be sent back to the JMSReplyTo Destination.
from("activemq:My.Queue").
to("velocity:com/acme/MyResponse.vm");
If you want to use InOnly and consume the message and send it to another
destination you could use
from("activemq:My.Queue").
to("velocity:com/acme/MyResponse.vm").
to("activemq:Another.Queue");
See Also
• Mock for details of mock endpoint testing (as opposed to template
based stubs).
DATABASE
Camel can work with databases in a number of different ways. This
document tries to outline the most common approaches.
Database endpoints
Camel provides a number of different endpoints for working with databases
• JPA for working with hibernate, openjpa or toplink. When consuming
from the endpoints entity beans are read (and deleted/updated to
mark as processed) then when producing to the endpoints they are
written to the database (via insert/update).
• iBATIS similar to the above but using Apache iBATIS
• JDBC similar though using explicit SQL
Database pattern implementations
Various patterns can work with databases as follows
• Idempotent Consumer
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• Aggregator
• BAM for business activity monitoring
PARALLEL PROCESSING AND ORDERING
It is a common requirement to want to use parallel processing of messages
for throughput and load balancing, while at the same time process certain
kinds of messages in order.
How to achieve parallel processing
You can send messages to a number of Camel Components to achieve
parallel processing and load balancing such as
• SEDA for in-JVM load balancing across a thread pool
• ActiveMQ or JMS for distributed load balancing and parallel
processing
• JPA for using the database as a poor mans message broker
When processing messages concurrently, you should consider ordering and
concurrency issues. These are described below
Concurrency issues
Note that there is no concurrency or locking issue when using ActiveMQ, JMS
or SEDA by design; they are designed for highly concurrent use. However
there are possible concurrency issues in the Processor of the messages i.e.
what the processor does with the message?
For example if a processor of a message transfers money from one
account to another account; you probably want to use a database with
pessimistic locking to ensure that operation takes place atomically.
Ordering issues
As soon as you send multiple messages to different threads or processes you
will end up with an unknown ordering across the entire message stream as
each thread is going to process messages concurrently.
For many use cases the order of messages is not too important. However
for some applications this can be crucial. e.g. if a customer submits a
purchase order version 1, then amends it and sends version 2; you don't
want to process the first version last (so that you loose the update). Your
Processor might be clever enough to ignore old messages. If not you need to
preserve order.
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Recommendations
This topic is large and diverse with lots of different requirements; but from a
high level here are our recommendations on parallel processing, ordering
and concurrency
• for distributed locking, use a database by default, they are very good
at it
• to preserve ordering across a JMS queue consider using Exclusive
Consumers in the ActiveMQ component
• even better are Message Groups which allows you to preserve
ordering across messages while still offering parallelisation via the
JMSXGrouopID header to determine what can be parallelized
• if you receive messages out of order you could use the Resequencer
to put them back together again
A good rule of thumb to help reduce ordering problems is to make sure each
single can be processed as an atomic unit in parallel (either without
concurrency issues or using say, database locking); or if it can't, use a
Message Group to relate the messages together which need to be processed
in order by a single thread.
Using Message Groups with Camel
To use a Message Group with Camel you just need to add a header to the
output JMS message based on some kind of Correlation Identifier to correlate
messages which should be processed in order by a single thread - so that
things which don't correlate together can be processed concurrently.
For example the following code shows how to create a message group
using an XPath expression taking an invoice's product code as the Correlation
Identifier
from("activemq:a").setHeader("JMSXGroupID", xpath("/invoice/
productCode")).to("activemq:b");
You can of course use the Xml Configuration if you prefer
ASYNCHRONOUS PROCESSING
Overview
Camel supports a more complex asynchronous processing model. The
asynchronous processors implement the AsyncProcessor interface which is
derived from the more synchronous Processor interface. There are
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Supported versions
The information on this page applies for the Camel 1.x and Camel
2.4 onwards. In Camel 1.x the asynchronous processing is only
implemented for JBI where as in Camel 2.4 onwards we have
implemented it in many other areas. See more at Asynchronous
Routing Engine.
advantages and disadvantages when using asynchronous processing when
compared to using the standard synchronous processing model.
Advantages:
• Processing routes that are composed fully of asynchronous
processors do not use up threads waiting for processors to complete
on blocking calls. This can increase the scalability of your system by
reducing the number of threads needed to process the same
workload.
• Processing routes can be broken up into SEDA processing stages
where different thread pools can process the different stages. This
means that your routes can be processed concurrently.
Disadvantages:
• Implementing asynchronous processors is more complex than
implementing the synchronous versions.
When to Use
We recommend that processors and components be implemented the more
simple synchronous APIs unless you identify a performance of scalability
requirement that dictates otherwise. A Processor whose process() method
blocks for a long time would be good candidates for being converted into an
asynchronous processor.
Interface Details
public interface AsyncProcessor extends Processor {
boolean process(Exchange exchange, AsyncCallback callback);
}
The AsyncProcessor defines a single process() method which is very similar
to it's synchronous Processor.process() brethren. Here are the differences:
• A non-null AsyncCallback MUST be supplied which will be notified
when the exchange processing is completed.
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• It MUST not throw any exceptions that occurred while processing the
exchange. Any such exceptions must be stored on the exchange's
Exception property.
• It MUST know if it will complete the processing synchronously or
asynchronously. The method will return true if it does complete
synchronously, otherwise it returns false.
• When the processor has completed processing the exchange, it must
call the callback.done(boolean sync) method. The sync
parameter MUST match the value returned by the process()
method.
Implementing Processors that Use the AsyncProcessor API
All processors, even synchronous processors that do not implement the
AsyncProcessor interface, can be coerced to implement the AsyncProcessor
interface. This is usually done when you are implementing a Camel
component consumer that supports asynchronous completion of the
exchanges that it is pushing through the Camel routes. Consumers are
provided a Processor object when created. All Processor object can be
coerced to a AsyncProcessor using the following API:
Processor processor = ...
AsyncProcessor asyncProcessor = AsyncProcessorTypeConverter.convert(processor);
For a route to be fully asynchronous and reap the benefits to lower Thread
usage, it must start with the consumer implementation making use of the
asynchronous processing API. If it called the synchronous process() method
instead, the consumer's thread would be forced to be blocked and in use for
the duration that it takes to process the exchange.
It is important to take note that just because you call the asynchronous
API, it does not mean that the processing will take place asynchronously. It
only allows the possibility that it can be done without tying up the caller's
thread. If the processing happens asynchronously is dependent on the
configuration of the Camel route.
Normally, the the process call is passed in an inline inner AsyncCallback
class instance which can reference the exchange object that was declared
final. This allows it to finish up any post processing that is needed when the
called processor is done processing the exchange. See below for an example.
final Exchange exchange = ...
AsyncProcessor asyncProcessor = ...
asyncProcessor.process(exchange, new AsyncCallback() {
public void done(boolean sync) {
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if (exchange.isFailed()) {
... // do failure processing.. perhaps rollback etc.
} else {
... // processing completed successfully, finish up
// perhaps commit etc.
}
}
});
Asynchronous Route Sequence Scenarios
Now that we have understood the interface contract of the AsyncProcessor,
and have seen how to make use of it when calling processors, lets looks a
what the thread model/sequence scenarios will look like for some sample
routes.
The Jetty component's consumers support async processing by using
continuations. Suffice to say it can take a http request and pass it to a camel
route for async processing. If the processing is indeed async, it uses Jetty
continuation so that the http request is 'parked' and the thread is released.
Once the camel route finishes processing the request, the jetty component
uses the AsyncCallback to tell Jetty to 'un-park' the request. Jetty un-parks
the request, the http response returned using the result of the exchange
processing.
Notice that the jetty continuations feature is only used "If the processing is
indeed async". This is why AsyncProcessor.process() implementations MUST
accurately report if request is completed synchronously or not.
The jhc component's producer allows you to make HTTP requests and
implement the AsyncProcessor interface. A route that uses both the jetty
asynchronous consumer and the jhc asynchronous producer will be a fully
asynchronous route and has some nice attributes that can be seen if we take
a look at a sequence diagram of the processing route. For the route:
from("jetty:http://localhost:8080/service").to("jhc:http://localhost/service-impl");
The sequence diagram would look something like this:
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COOKBOOK
The diagram simplifies things by making it looks like processors implement
the AsyncCallback interface when in reality the AsyncCallback interfaces are
inline inner classes, but it illustrates the processing flow and shows how 2
separate threads are used to complete the processing of the original http
request. The first thread is synchronous up until processing hits the jhc
producer which issues the http request. It then reports that the exchange
processing will complete async since it will use a NIO to complete getting the
response back. Once the jhc component has received a full response it uses
AsyncCallback.done() method to notify the caller. These callback
notifications continue up until it reaches the original jetty consumer which
then un-parks the http request and completes it by providing the response.
Mixing Synchronous and Asynchronous Processors
It is totally possible and reasonable to mix the use of synchronous and
asynchronous processors/components. The pipeline processor is the
backbone of a Camel processing route. It glues all the processing steps
together. It is implemented as an AsyncProcessor and supports interleaving
synchronous and asynchronous processors as the processing steps in the
pipeline.
Lets say we have 2 custom processors, MyValidator and MyTransformation,
both of which are synchronous processors. Lets say we want to load file from
the data/in directory validate them with the MyValidator() processor,
Transform them into JPA java objects using MyTransformation and then insert
them into the database using the JPA component. Lets say that the
transformation process takes quite a bit of time and we want to allocate 20
threads to do parallel transformations of the input files. The solution is to
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make use of the thread processor. The thread is AsyncProcessor that forces
subsequent processing in asynchronous thread from a thread pool.
The route might look like:
from("file:data/in").process(new MyValidator()).threads(20).process(new
MyTransformation()).to("jpa:PurchaseOrder");
The sequence diagram would look something like this:
You would actually have multiple threads executing the 2nd part of the
thread sequence.
Staying synchronous in an AsyncProcessor
Generally speaking you get better throughput processing when you process
things synchronously. This is due to the fact that starting up an asynchronous
thread and doing a context switch to it adds a little bit of of overhead. So it is
generally encouraged that AsyncProcessors do as much work as they can
synchronously. When they get to a step that would block for a long time, at
that point they should return from the process call and let the caller know
that it will be completing the call asynchronously.
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IMPLEMENTING VIRTUAL TOPICS ON OTHER JMS
PROVIDERS
ActiveMQ supports Virtual Topics since durable topic subscriptions kinda suck
(see this page for more detail) mostly since they don't support Competing
Consumers.
Most folks want Queue semantics when consuming messages; so that you
can support Competing Consumers for load balancing along with things like
Message Groups and Exclusive Consumers to preserve ordering or partition
the queue across consumers.
However if you are using another JMS provider you can implement Virtual
Topics by switching to ActiveMQ
or you can use the following Camel
pattern.
First here's the ActiveMQ approach.
• send to activemq:topic:VirtualTopic.Orders
• for consumer A consume from
activemq:Consumer.A.VirtualTopic.Orders
When using another message broker use the following pattern
• send to jms:Orders
• add this route with a to() for each logical durable topic subscriber
from("jms:Orders").to("jms:Consumer.A", "jms:Consumer.B", ...);
• for consumer A consume from jms:Consumer.A
WHAT'S THE CAMEL TRANSPORT FOR CXF
In CXF you offer or consume a webservice by defining it´s address. The first
part of the address specifies the protocol to use. For example
address="http://localhost:90000" in an endpoint configuration means your
service will be offered using the http protocol on port 9000 of localhost.
When you integrate Camel Tranport into CXF you get a new transport
"camel". So you can specify address="camel://direct:MyEndpointName" to
bind the CXF service address to a camel direct endpoint.
Technically speaking Camel transport for CXF is a component which
implements the CXF transport API with the Camel core library. This allows you
to use camel´s routing engine and integration patterns support smoothly
together with your CXF services.
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INTEGRATE CAMEL INTO CXF TRANSPORT LAYER
To include the Camel Tranport into your CXF bus you use the
CamelTransportFactory. You can do this in Java as well as in Spring.
Setting up the Camel Transport in Spring
You can use the following snippet in your applicationcontext if you want to
configure anything special. If you only want to activate the camel transport
you do not have to do anything in your application context. As soon as you
include the camel-cxf jar in your app cxf will scan the jar and load a
CamelTransportFactory for you.
http://cxf.apache.org/transports/camel
Integrating the Camel Transport in a programmatic way
Camel transport provides a setContext method that you could use to set the
Camel context into the transport factory. If you want this factory take effect,
you need to register the factory into the CXF bus. Here is a full example for
you.
import
import
import
import
...
org.apache.cxf.Bus;
org.apache.cxf.BusFactory;
org.apache.cxf.transport.ConduitInitiatorManager;
org.apache.cxf.transport.DestinationFactoryManager;
BusFactory bf = BusFactory.newInstance();
Bus bus = bf.createBus();
CamelTransportFactory camelTransportFactory = new CamelTransportFactory();
camelTransportFactory.setCamelContext(context)
// register the conduit initiator
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ConduitInitiatorManager cim = bus.getExtension(ConduitInitiatorManager.class);
cim.registerConduitInitiator(CamelTransportFactory.TRANSPORT_ID,
camelTransportFactory);
// register the destination factory
DestinationFactoryManager dfm = bus.getExtension(DestinationFactoryManager.class);
dfm.registerDestinationFactory(CamelTransportFactory.TRANSPORT_ID,
camelTransportFactory);
// set or bus as the default bus for cxf
BusFactory.setDefaultBus(bus);
CONFIGURE THE DESTINATION AND CONDUIT
Namespace
The elements used to configure an Camel transport endpoint are defined in
the namespace http://cxf.apache.org/transports/camel. It is commonly
referred to using the prefix camel. In order to use the Camel transport
configuration elements you will need to add the lines shown below to the
beans element of your endpoint's configuration file. In addition, you will need
to add the configuration elements' namespace to the xsi:schemaLocation
attribute.
Listing 14. Adding the Configuration Namespace
The destination element
You configure an Camel transport server endpoint using the
camel:destination element and its children. The camel:destination
element takes a single attribute, name, the specifies the WSDL port element
that corresponds to the endpoint. The value for the name attribute takes the
form portQName.camel-destination. The example below shows the
camel:destination element that would be used to add configuration for an
endpoint that was specified by the WSDL fragment
...
The camel:destination element has a number of child elements that
specify configuration information. They are described below.
Element
Description
camelspring:camelContext
You can specify the camel context in the camel
destination
camel:camelContextRef
The camel context id which you want inject
into the camel destination
The conduit element
You configure an Camel transport client using the camel:conduit element
and its children. The camel:conduit element takes a single attribute, name,
that specifies the WSDL port element that corresponds to the endpoint. The
value for the name attribute takes the form portQName.camel-conduit. For
example, the code below shows the camel:conduit element that would be
used to add configuration for an endpoint that was specified by the WSDL
fragment conduit_context
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...
...
The camel:conduit element has a number of child elements that specify
configuration information. They are described below.
Element
Description
camelspring:camelContext
You can specify the camel context in the camel
conduit
camel:camelContextRef
The camel context id which you want inject
into the camel conduit
EXAMPLE USING CAMEL AS A LOAD BALANCER FOR CXF
This example show how to use the camel load balance feature in CXF, and
you need load the configuration file in CXF and publish the endpoints on the
address "camel://direct:EndpointA" and "camel://direct:EndpointB"
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dest_context
COMPLETE HOWTO AND EXAMPLE FOR ATTACHING
CAMEL TO CXF
Introduction
Better JMS Transport for CXF Webservice using Apache Camel
When sending an Exchange to an Endpoint you can either use a Route or a
ProducerTemplate. This works fine in many scenarios. However you may
need to guarantee that an exchange is delivered to the same endpoint that
you delivered a previous exchange on. For example in the case of delivering
a batch of exchanges to a MINA socket you may need to ensure that they are
all delivered through the same socket connection. Furthermore once the
batch of exchanges have been delivered the protocol requirements may be
such that you are responsible for closing the socket.
Using a Producer
To achieve fine grained control over sending exchanges you will need to
program directly to a Producer. Your code will look similar to:
CamelContext camelContext = ...
// Obtain an endpoint and create the producer we will be using.
Endpoint endpoint = camelContext.getEndpoint("someuri:etc");
Producer producer = endpoint.createProducer();
producer.start();
try {
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// For each message to send...
Object requestMessage = ...
Exchange exchangeToSend = producer.createExchange();
exchangeToSend().setBody(requestMessage);
producer.process(exchangeToSend);
...
} finally {
// Tidy the producer up.
producer.stop();
}
In the case of using Apache MINA the producer.stop() invocation will cause
the socket to be closed.
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Tutorials
There now follows the documentation on camel tutorials
• OAuth Tutorial
This tutorial demonstrates how to implement OAuth for a web
application with Camel's gauth component. The sample application of
this tutorial is also online at http://gauthcloud.appspot.com/
• Tutorial for Camel on Google App Engine
This tutorial demonstrates the usage of the Camel Components for
Google App Engine. The sample application of this tutorial is also
online at http://camelcloud.appspot.com/
• Tutorial on Spring Remoting with JMS
This tutorial is focused on different techniques with Camel for ClientServer communication.
• Report Incident - This tutorial introduces Camel steadily and is based
on a real life integration problem
This is a very long tutorial beginning from the start; its for entry level
to Camel. Its based on a real life integration, showing how Camel can
be introduced in an existing solution. We do this in baby steps. The
tutorial is currently work in progress, so check it out from time to
time. The tutorial explains some of the inner building blocks Camel
uses under the covers. This is good knowledge to have when you
start using Camel on a higher abstract level where it can do wonders
in a few lines of routing DSL.
• Using Camel with ServiceMix a tutorial on using Camel inside Apache
ServiceMix.
• Better JMS Transport for CXF Webservice using Apache Camel
Describes how to use the Camel Transport for CXF to attach a CXF
Webservice to a JMS Queue
• Tutorial how to use good old Axis 1.4 with Camel
This tutorial shows that Camel does work with the good old
frameworks such as AXIS that is/was widely used for WebService.
• Tutorial on using Camel in a Web Application
This tutorial gives an overview of how to use Camel inside Tomcat,
Jetty or any other servlet engine
• Tutorial on Camel 1.4 for Integration
Another real-life scenario. The company sells widgets, with a
somewhat unique business process (their customers periodically
report what they've purchased in order to get billed). However every
customer uses a different data format and protocol. This tutorial goes
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through the process of integrating (and testing!) several customers
and their electronic reporting of the widgets they've bought, along
with the company's response.
• Tutorial how to build a Service Oriented Architecture using Camel
with OSGI - Updated 20/11/2009
The tutorial has been designed in two parts. The first part introduces
basic concept to create a simple SOA solution using Camel and OSGI
and deploy it in a OSGI Server like Apache Felix Karaf and Spring DM
Server while the second extends the ReportIncident tutorial part 4 to
show How we can separate the different layers (domain, service, ...)
of an application and deploy them in separate bundles. The Web
Application has also be modified in order to communicate to the OSGI
bundles.
• Several of the vendors on the Commercial Camel Offerings page also
offer various tutorials, webinars, examples, etc.... that may be useful.
• Examples
While not actual tutorials you might find working through the source
of the various Examples useful.
TUTORIAL ON SPRING REMOTING WITH JMS
PREFACE
This tutorial aims to guide the reader through the stages of creating a project
which uses Camel to facilitate the routing of messages from a JMS queue to a
Spring service. The route works in a synchronous fashion returning a
response to the client.
• Tutorial on Spring Remoting with JMS
• Preface
• Prerequisites
• Distribution
• About
• Create the Camel Project
• Update the POM with Dependencies
• Writing the Server
• Create the Spring Service
• Define the Camel Routes
• Configure Spring
• AOP Enabled Server
• Run the Server
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Thanks
This tutorial was kindly donated to Apache Camel by Martin Gilday.
•
•
•
•
•
•
•
•
Writing The Clients
Client Using The ProducerTemplate
Client Using Spring Remoting
Client Using Message Endpoint EIP Pattern
Run the Clients
Using the Camel Maven Plugin
Using Camel JMX
See Also
PREREQUISITES
This tutorial uses Maven to setup the Camel project and for dependencies for
artifacts.
DISTRIBUTION
This sample is distributed with the Camel distribution as examples/camelexample-spring-jms.
ABOUT
This tutorial is a simple example that demonstrates more the fact how well
Camel is seamless integrated with Spring to leverage the best of both worlds.
This sample is client server solution using JMS messaging as the transport.
The sample has two flavors of servers and also for clients demonstrating
different techniques for easy communication.
The Server is a JMS message broker that routes incoming messages to a
business service that does computations on the received message and
returns a response.
The EIP patterns used in this sample are:
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Pattern
Description
Message
Channel
We need a channel so the Clients can communicate with the
server.
Message
The information is exchanged using the Camel Message
interface.
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Message
Translator
This is where Camel shines as the message exchange
between the Server and the Clients are text based strings with
numbers. However our business service uses int for numbers.
So Camel can do the message translation automatically.
Message
Endpoint
It should be easy to send messages to the Server from the the
clients. This is archived with Camels powerful Endpoint
pattern that even can be more powerful combined with Spring
remoting. The tutorial have clients using each kind of
technique for this.
Point to
Point
Channel
We using JMS queues so there are only one receive of the
message exchange
Event
Driven
Consumer
Yes the JMS broker is of course event driven and only reacts
when the client sends a message to the server.
We use the following Camel components:
Component
Description
ActiveMQ
We use Apache ActiveMQ as the JMS broker on the Server
side
Bean
We use the bean binding to easily route the messages to
our business service. This is a very powerful component in
Camel.
File
In the AOP enabled Server we store audit trails as files.
JMS
Used for the JMS messaging
CREATE THE CAMEL PROJECT
mvn archetype:create -DgroupId=org.example -DartifactId=CamelWithJmsAndSpring
Update the POM with Dependencies
First we need to have dependencies for the core Camel jars, its spring, jms
components and finally ActiveMQ as the message broker.
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112
For the purposes of the tutorial a single Maven project will be used
for both the client and server. Ideally you would break your
application down into the appropriate components.
org.apache.camelcamel-coreorg.apache.camelcamel-jmsorg.apache.camelcamel-springorg.apache.activemqactivemq-camel
As we use spring xml configuration for the ActiveMQ JMS broker we need this
dependency:
org.apache.xbeanxbean-spring
And dependencies for the AOP enable server example. These dependencies
are of course only needed if you need full blown AOP stuff using AspejctJ with
bytecode instrumentation.
org.springframeworkspring-aop${spring-version}org.aspectjaspectjrt1.6.2org.aspectj
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aspectjweaver1.6.2cglibcglib-nodep2.1_3
WRITING THE SERVER
Create the Spring Service
For this example the Spring service (= our business service) on the server
will be a simple multiplier which trebles in the received value.
public interface Multiplier {
/**
* Multiplies the given number by a pre-defined constant.
*
* @param originalNumber The number to be multiplied
* @return The result of the multiplication
*/
int multiply(int originalNumber);
}
And the implementation of this service is:
@Service(value = "multiplier")
public class Treble implements Multiplier {
public int multiply(final int originalNumber) {
return originalNumber * 3;
}
}
Notice that this class has been annotated with the @Service spring
annotation. This ensures that this class is registered as a bean in the registry
with the given name multiplier.
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Define the Camel Routes
public class ServerRoutes extends RouteBuilder {
@Override
public void configure() throws Exception {
// route from the numbers queue to our business that is a spring bean
registered with the id=multiplier
// Camel will introspect the multiplier bean and find the best candidate of
the method to invoke.
// You can add annotations etc to help Camel find the method to invoke.
// As our multiplier bean only have one method its easy for Camel to find the
method to use.
from("jms:queue:numbers").to("multiplier");
// Camel has several ways to configure the same routing, we have defined some
of them here below
// as above but with the bean: prefix
//from("jms:queue:numbers").to("bean:multiplier");
// beanRef is using explicity bean bindings to lookup the multiplier bean and
invoke the multiply method
//from("jms:queue:numbers").beanRef("multiplier", "multiply");
// the same as above but expressed as a URI configuration
//from("activemq:queue:numbers").to("bean:multiplier?methodName=multiply");
}
}
This defines a Camel route from the JMS queue named numbers to the
Spring bean named multiplier. Camel will create a consumer to the JMS
queue which forwards all received messages onto the the Spring bean, using
the method named multiply.
Configure Spring
The Spring config file is placed under META-INF/spring as this is the default
location used by the Camel Maven Plugin, which we will later use to run our
server.
First we need to do the standard scheme declarations in the top. In the
camel-server.xml we are using spring beans as the default bean: namespace
and springs context:. For configuring ActiveMQ we use broker: and for
Camel we of course have camel:. Notice that we don't use version numbers
for the camel-spring schema. At runtime the schema is resolved in the Camel
bundle. If we use a specific version number such as 1.4 then its IDE friendly
as it would be able to import it and provide smart completion etc. See Xml
Reference for further details.
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We use Spring annotations for doing IoC dependencies and its componentscan features comes to the rescue as it scans for spring annotations in the
given package name:
Camel will of course not be less than Spring in this regard so it supports a
similar feature for scanning of Routes. This is configured as shown below.
Notice that we also have enabled the JMXAgent so we will be able to
introspect the Camel Server with a JMX Console.
org.apache.camel.example.server
The ActiveMQ JMS broker is also configured in this xml file. We set it up to
listen on TCP port 61610.
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116
As this examples uses JMS then Camel needs a JMS component that is
connected with the ActiveMQ broker. This is configured as shown below:
Notice: The JMS component is configured in standard Spring beans, but the
gem is that the bean id can be referenced from Camel routes - meaning we
can do routing using the JMS Component by just using jms: prefix in the
route URI. What happens is that Camel will find in the Spring Registry for a
bean with the id="jms". Since the bean id can have arbitrary name you could
have named it id="jmsbroker" and then referenced to it in the routing as
from="jmsbroker:queue:numbers).to("multiplier");
We use the vm protocol to connect to the ActiveMQ server as its embedded
in this application.
componentscan
Defines the package to be scanned for Spring stereotype
annotations, in this case, to load the "multiplier" bean
camelcontext
Defines the package to be scanned for Camel routes. Will
find the ServerRoutes class and create the routes
contained within it
jms bean
Creates the Camel JMS component
AOP Enabled Server
The example has an enhanced Server example that uses fullblown AspejctJ
AOP for doing a audit tracking of invocations of the business service.
We leverage Spring AOP support in the {{camel-server-aop.xml}
configuration file. First we must declare the correct XML schema's to use:
Then we include all the existing configuration from the normal server
example:
Then we enable the AspejctJ AOP auto proxy feature of Spring that will scan
for classes annotated with the @Aspect annotation:
Then we define our Audit tracker bean that does the actual audit logging. It's
also the class that is annotated with the @Aspect so Spring will pick this up,
as the aspect.
And the gem is that we inject the AuditTracker aspect bean with a Camel
endpoint that defines where the audit should be stored. Noticed how easy it
is to setup as we have just defined an endpoint URI that is file based,
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118
meaning that we stored the audit tracks as files. We can change this tore to
any Camel components as we wish. To store it on a JMS queue simply change
the URI to jms:queue:audit.
org.apache.camel.example.server
And the full blown Aspejct for the audit tracker java code:
/**
* For audit tracking of all incoming invocations of our business (Multiplier)
*/
@Aspect
public class AuditTracker {
// endpoint we use for backup store of audit tracks
private Endpoint store;
@Required
public void setStore(Endpoint store) {
this.store = store;
}
@Before("execution(int org.apache.camel.example.server.Multiplier.multiply(int))
&& args(originalNumber)")
public void audit(int originalNumber) throws Exception {
String msg = "Someone called us with this number " + originalNumber;
System.out.println(msg);
// now send the message to the backup store using the Camel Message Endpoint
pattern
Exchange exchange = store.createExchange();
exchange.getIn().setBody(msg);
store.createProducer().process(exchange);
}
}
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Run the Server
The Server is started using the org.apache.camel.spring.Main class that
can start camel-spring application out-of-the-box. The Server can be started
in several flavors:
▪ as a standard java main application - just start the
org.apache.camel.spring.Main class
▪ using maven jave:exec
▪ using camel:run
In this sample as there are two servers (with and without AOP) we have
prepared some profiles in maven to start the Server of your choice.
The server is started with:
mvn compile exec:java -PCamelServer
Or for the AOP enabled Server example:
mvn compile exec:java -PCamelServerAOP
WRITING THE CLIENTS
This sample has three clients demonstrating different Camel techniques for
communication
▪ CamelClient using the ProducerTemplate for Spring template style
coding
▪ CamelRemoting using Spring Remoting
▪ CamelEndpoint using the Message Endpoint EIP pattern using a
neutral Camel API
Client Using The ProducerTemplate
We will initially create a client by directly using ProducerTemplate. We will
later create a client which uses Spring remoting to hide the fact that
messaging is being used.
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The client will not use the Camel Maven Plugin so the Spring XML has been
placed in src/main/resources to not conflict with the server configs.
camelContext
The Camel context is defined but does not contain any
routes
template
The ProducerTemplate is used to place messages onto
the JMS queue
jms bean
This initialises the Camel JMS component, allowing us to
place messages onto the queue
And the CamelClient source code:
public static void main(final String[] args) throws Exception {
System.out.println("Notice this client requires that the CamelServer is already
running!");
ApplicationContext context = new
ClassPathXmlApplicationContext("camel-client.xml");
// get the camel template for Spring template style sending of messages (=
producer)
ProducerTemplate camelTemplate = (ProducerTemplate)
context.getBean("camelTemplate");
System.out.println("Invoking the multiply with 22");
// as opposed to the CamelClientRemoting example we need to define the service
URI in this java code
int response = (Integer)camelTemplate.sendBody("jms:queue:numbers",
ExchangePattern.InOut, 22);
System.out.println("... the result is: " + response);
System.exit(0);
}
The ProducerTemplate is retrieved from a Spring ApplicationContext and
used to manually place a message on the "numbers" JMS queue. The
exchange pattern (ExchangePattern.InOut) states that the call should be
synchronous, and that we will receive a response.
Before running the client be sure that both the ActiveMQ broker and the
CamelServer are running.
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Client Using Spring Remoting
Spring Remoting "eases the development of remote-enabled services". It
does this by allowing you to invoke remote services through your regular
Java interface, masking that a remote service is being called.
The snippet above only illustrates the different and how Camel easily can
setup and use Spring Remoting in one line configurations.
The proxy will create a proxy service bean for you to use to make the
remote invocations. The serviceInterface property details which Java
interface is to be implemented by the proxy. serviceUrl defines where
messages sent to this proxy bean will be directed. Here we define the JMS
endpoint with the "numbers" queue we used when working with Camel
template directly. The value of the id property is the name that will be the
given to the bean when it is exposed through the Spring
ApplicationContext. We will use this name to retrieve the service in our
client. I have named the bean multiplierProxy simply to highlight that it is not
the same multiplier bean as is being used by CamelServer. They are in
completely independent contexts and have no knowledge of each other. As
you are trying to mask the fact that remoting is being used in a real
application you would generally not include proxy in the name.
And the Java client source code:
public static void main(final String[] args) {
System.out.println("Notice this client requires that the CamelServer is already
running!");
ApplicationContext context = new
ClassPathXmlApplicationContext("camel-client-remoting.xml");
// just get the proxy to the service and we as the client can use the "proxy" as
it was
// a local object we are invoking. Camel will under the covers do the remote
communication
// to the remote ActiveMQ server and fetch the response.
Multiplier multiplier = (Multiplier)context.getBean("multiplierProxy");
System.out.println("Invoking the multiply with 33");
int response = multiplier.multiply(33);
System.out.println("... the result is: " + response);
System.exit(0);
}
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Again, the client is similar to the original client, but with some important
differences.
1. The Spring context is created with the new camel-client-remoting.xml
2. We retrieve the proxy bean instead of a ProducerTemplate. In a nontrivial example you would have the bean injected as in the standard
Spring manner.
3. The multiply method is then called directly. In the client we are now
working to an interface. There is no mention of Camel or JMS inside
our Java code.
Client Using Message Endpoint EIP Pattern
This client uses the Message Endpoint EIP pattern to hide the complexity to
communicate to the Server. The Client uses the same simple API to get hold
of the endpoint, create an exchange that holds the message, set the payload
and create a producer that does the send and receive. All done using the
same neutral Camel API for all the components in Camel. So if the
communication was socket TCP based you just get hold of a different
endpoint and all the java code stays the same. That is really powerful.
Okay enough talk, show me the code!
public static void main(final String[] args) throws Exception {
System.out.println("Notice this client requires that the CamelServer is already
running!");
ApplicationContext context = new
ClassPathXmlApplicationContext("camel-client.xml");
CamelContext camel = (CamelContext) context.getBean("camel-client");
// get the endpoint from the camel context
Endpoint endpoint = camel.getEndpoint("jms:queue:numbers");
// create the exchange used for the communication
// we use the in out pattern for a synchronized exchange where we expect a
response
Exchange exchange = endpoint.createExchange(ExchangePattern.InOut);
// set the input on the in body
// must you correct type to match the expected type of an Integer object
exchange.getIn().setBody(11);
// to send the exchange we need an producer to do it for us
Producer producer = endpoint.createProducer();
// start the producer so it can operate
producer.start();
// let the producer process the exchange where it does all the work in this
oneline of code
System.out.println("Invoking the multiply with 11");
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producer.process(exchange);
// get the response from the out body and cast it to an integer
int response = exchange.getOut().getBody(Integer.class);
System.out.println("... the result is: " + response);
// stop and exit the client
producer.stop();
System.exit(0);
}
Switching to a different component is just a matter of using the correct
endpoint. So if we had defined a TCP endpoint as:
"mina:tcp://localhost:61610" then its just a matter of getting hold of this
endpoint instead of the JMS and all the rest of the java code is exactly the
same.
Run the Clients
The Clients is started using their main class respectively.
▪ as a standard java main application - just start their main class
▪ using maven jave:exec
In this sample we start the clients using maven:
mvn compile exec:java -PCamelClient
mvn compile exec:java -PCamelClientRemoting
mvn compile exec:java -PCamelClientEndpoint
Also see the Maven pom.xml file how the profiles for the clients is defined.
USING THE CAMEL MAVEN PLUGIN
The Camel Maven Plugin allows you to run your Camel routes directly from
Maven. This negates the need to create a host application, as we did with
Camel server, simply to start up the container. This can be very useful during
development to get Camel routes running quickly.
Listing 17. pom.xml
org.apache.camelcamel-maven-plugin
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All that is required is a new plugin definition in your Maven POM. As we have
already placed our Camel config in the default location (camel-server.xml has
been placed in META-INF/spring/) we do not need to tell the plugin where the
route definitions are located. Simply run mvn camel:run.
USING CAMEL JMX
Camel has extensive support for JMX and allows us to inspect the Camel
Server at runtime. As we have enabled the JMXAgent in our tutorial we can
fire up the jconsole and connect to the following service URI:
service:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi/camel. Notice
that Camel will log at INFO level the JMX Connector URI:
...
DefaultInstrumentationAgent
INFO JMX connector thread started on
service:jmx:rmi:///jndi/rmi://claus-acer:1099/jmxrmi/camel
...
In the screenshot below we can see the route and its performance metrics:
SEE ALSO
• Spring Remoting with JMS Example on Amin Abbaspour's Weblog
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TUTORIAL - CAMEL-EXAMPLE-REPORTINCIDENT
INTRODUCTION
Creating this tutorial was inspired by a real life use-case I discussed over the
phone with a colleague. He was working at a client whom uses a heavyweight integration platform from a very large vendor. He was in talks with
developer shops to implement a new integration on this platform. His trouble
was the shop tripled the price when they realized the platform of choice. So I
was wondering how we could do this integration with Camel. Can it be done,
without tripling the cost
.
This tutorial is written during the development of the integration. I have
decided to start off with a sample that isn't Camel's but standard Java and
then plugin Camel as we goes. Just as when people needed to learn Spring
you could consume it piece by piece, the same goes with Camel.
The target reader is person whom hasn't experience or just started using
Camel.
MOTIVATION FOR THIS TUTORIAL
I wrote this tutorial motivated as Camel lacked an example application that
was based on the web application deployment model. The entire world hasn't
moved to pure OSGi deployments yet.
THE USE-CASE
The goal is to allow staff to report incidents into a central administration. For
that they use client software where they report the incident and submit it to
the central administration. As this is an integration in a transition phase the
administration should get these incidents by email whereas they are
manually added to the database. The client software should gather the
incident and submit the information to the integration platform that in term
will transform the report into an email and send it to the central
administrator for manual processing.
The figure below illustrates this process. The end users reports the
incidents using the client applications. The incident is sent to the central
integration platform as webservice. The integration platform will process the
incident and send an OK acknowledgment back to the client. Then the
integration will transform the message to an email and send it to the
administration mail server. The users in the administration will receive the
emails and take it from there.
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126
In EIP patterns
We distill the use case as EIP patterns:
PARTS
This tutorial is divided into sections and parts:
Section A: Existing Solution, how to slowly use Camel
Part 1 - This first part explain how to setup the project and get a
webservice exposed using Apache CXF. In fact we don't touch Camel yet.
Part 2 - Now we are ready to introduce Camel piece by piece (without
using Spring or any XML configuration file) and create the full feature
integration. This part will introduce different Camel's concepts and How we
can build our solution using them like :
▪ CamelContext
▪ Endpoint, Exchange & Producer
▪ Components : Log, File
Part 3 - Continued from part 2 where we implement that last part of the
solution with the event driven consumer and how to send the email through
the Mail component.
Section B: The Camel Solution
Part 4 - We now turn into the path of Camel where it excels - the routing.
Part 5 - Is about how embed Camel with Spring and using CXF endpoints
directly in Camel
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Using Axis 2
See this blog entry by Sagara demonstrating how to use Apache
Axis 2 instead of Apache CXF as the web service framework.
LINKS
▪
▪
▪
▪
▪
▪
Introduction
Part 1
Part 2
Part 3
Part 4
Part 5
PART 1
PREREQUISITES
This tutorial uses the following frameworks:
• Maven 2.0.9
• Apache Camel 1.4.0
• Apache CXF 2.1.1
• Spring 2.5.5
Note: The sample project can be downloaded, see the resources section.
INITIAL PROJECT SETUP
We want the integration to be a standard .war application that can be
deployed in any web container such as Tomcat, Jetty or even heavy weight
application servers such as WebLogic or WebSphere. There fore we start off
with the standard Maven webapp project that is created with the following
long archetype command:
mvn archetype:create -DgroupId=org.apache.camel
-DartifactId=camel-example-reportincident -DarchetypeArtifactId=maven-archetype-webapp
Notice that the groupId etc. doens't have to be org.apache.camel it can be
com.mycompany.whatever. But I have used these package names as the
example is an official part of the Camel distribution.
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128
Then we have the basic maven folder layout. We start out with the
webservice part where we want to use Apache CXF for the webservice stuff.
So we add this to the pom.xml
2.1.1org.apache.cxfcxf-rt-core${cxf-version}org.apache.cxfcxf-rt-frontend-jaxws${cxf-version}org.apache.cxfcxf-rt-transports-http${cxf-version}
DEVELOPING THE WEBSERVICE
As we want to develop webservice with the contract first approach we create
our .wsdl file. As this is a example we have simplified the model of the
incident to only include 8 fields. In real life the model would be a bit more
complex, but not to much.
We put the wsdl file in the folder src/main/webapp/WEB-INF/wsdl and
name the file report_incident.wsdl.
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130
CXF wsdl2java
Then we integration the CXF wsdl2java generator in the pom.xml so we have
CXF generate the needed POJO classes for our webservice contract.
However at first we must configure maven to live in the modern world of Java
1.5 so we must add this to the pom.xml
org.apache.maven.pluginsmaven-compiler-plugin1.51.5
And then we can add the CXF wsdl2java code generator that will hook into
the compile goal so its automatic run all the time:
org.apache.cxfcxf-codegen-plugin${cxf-version}generate-sources
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generate-sources${basedir}/target/
generated/src/main/java${basedir}/src/main/webapp/WEB-INF/wsdl/report_incident.wsdlwsdl2java
You are now setup and should be able to compile the project. So running the
mvn compile should run the CXF wsdl2java and generate the source code in
the folder &{basedir}/target/generated/src/main/java that we specified
in the pom.xml above. Since its in the target/generated/src/main/java
maven will pick it up and include it in the build process.
Configuration of the web.xml
Next up is to configure the web.xml to be ready to use CXF so we can expose
the webservice.
As Spring is the center of the universe, or at least is a very important
framework in today's Java land we start with the listener that kick-starts
Spring. This is the usual piece of code:
org.springframework.web.context.ContextLoaderListener
And then we have the CXF part where we define the CXF servlet and its URI
mappings to which we have chosen that all our webservices should be in the
path /webservices/
CXFServletorg.apache.cxf.transport.servlet.CXFServlet
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132
1CXFServlet/webservices/*
Then the last piece of the puzzle is to configure CXF, this is done in a spring
XML that we link to fron the web.xml by the standard Spring
contextConfigLocation property in the web.xml
contextConfigLocationclasspath:cxf-config.xml
We have named our CXF configuration file cxf-config.xml and its located in
the root of the classpath. In Maven land that is we can have the cxfconfig.xml file in the src/main/resources folder. We could also have the
file located in the WEB-INF folder for instance /WEB-INF/cxfconfig.xml.
Getting rid of the old jsp world
The maven archetype that created the basic folder structure also created a
sample .jsp file index.jsp. This file src/main/webapp/index.jsp should be
deleted.
Configuration of CXF
The cxf-config.xml is as follows:
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The configuration is standard CXF and is documented at the Apache CXF
website.
The 3 import elements is needed by CXF and they must be in the file.
Noticed that we have a spring bean reportIncidentEndpoint that is the
implementation of the webservice endpoint we let CXF expose.
Its linked from the jaxws element with the implementator attribute as we use
the # mark to identify its a reference to a spring bean. We could have stated
the classname directly as
implementor="org.apache.camel.example.reportincident.ReportIncidentEndpoint
but then we lose the ability to let the ReportIncidentEndpoint be configured
by spring.
The address attribute defines the relative part of the URL of the exposed
webservice. wsdlLocation is an optional parameter but for persons like me
that likes contract-first we want to expose our own .wsdl contracts and not
the auto generated by the frameworks, so with this attribute we can link to
the real .wsdl file. The last stuff is needed by CXF as you could have several
services so it needs to know which this one is. Configuring these is quite easy
as all the information is in the wsdl already.
Implementing the ReportIncidentEndpoint
Phew after all these meta files its time for some java code so we should code
the implementor of the webservice. So we fire up mvn compile to let CXF
generate the POJO classes for our webservice and we are ready to fire up a
Java editor.
You can use mvn idea:idea or mvn eclipse:eclipse to create project
files for these editors so you can load the project. However IDEA has been
smarter lately and can load a pom.xml directly.
As we want to quickly see our webservice we implement just a quick and
dirty as it can get. At first beware that since its jaxws and Java 1.5 we get
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annotations for the money, but they reside on the interface so we can
remove them from our implementations so its a nice plain POJO again:
package org.apache.camel.example.reportincident;
/**
* The webservice we have implemented.
*/
public class ReportIncidentEndpointImpl implements ReportIncidentEndpoint {
public OutputReportIncident reportIncident(InputReportIncident parameters) {
System.out.println("Hello ReportIncidentEndpointImpl is called from " +
parameters.getGivenName());
OutputReportIncident out = new OutputReportIncident();
out.setCode("OK");
return out;
}
}
We just output the person that invokes this webservice and returns a OK
response. This class should be in the maven source root folder src/main/
java under the package name
org.apache.camel.example.reportincident. Beware that the maven
archetype tool didn't create the src/main/java folder, so you should
create it manually.
To test if we are home free we run mvn clean compile.
Running our webservice
Now that the code compiles we would like to run it in a web container, so we
add jetty to our pom.xml so we can run mvn jetty:run:
...
6.1.1
...
org.mortbay.jettymaven-jetty-plugin${jetty-version}
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Notice: We use Jetty v6.1.1 as never versions has troubles on my laptop.
Feel free to try a newer version on your system, but v6.1.1 works flawless.
So to see if everything is in order we fire up jetty with mvn jetty:run and
if everything is okay you should be able to access http://localhost:8080.
Jetty is smart that it will list the correct URI on the page to our web
application, so just click on the link. This is smart as you don't have to
remember the exact web context URI for your application - just fire up the
default page and Jetty will help you.
So where is the damn webservice then? Well as we did configure the
web.xml to instruct the CXF servlet to accept the pattern /webservices/*
we should hit this URL to get the attention of CXF: http://localhost:8080/
camel-example-reportincident/webservices.
Hitting the webservice
Now we have the webservice running in a standard .war application in a
standard web container such as Jetty we would like to invoke the webservice
and see if we get our code executed. Unfortunately this isn't the easiest task
in the world - its not so easy as a REST URL, so we need tools for this. So we
fire up our trusty webservice tool SoapUI and let it be the one to fire the
webservice request and see the response.
Using SoapUI we sent a request to our webservice and we got the
expected OK response and the console outputs the System.out so we are
ready to code.
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Remote Debugging
Okay a little sidestep but wouldn't it be cool to be able to debug your code
when its fired up under Jetty? As Jetty is started from maven, we need to
instruct maven to use debug mode.
Se we set the MAVEN_OPTS environment to start in debug mode and listen on
port 5005.
MAVEN_OPTS=-Xmx512m -XX:MaxPermSize=128m -Xdebug
-Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=5005
Then you need to restart Jetty so its stopped with ctrl + c. Remember to
start a new shell to pickup the new environment settings. And start jetty
again.
Then we can from our IDE attach a remote debugger and debug as we
want.
First we configure IDEA to attach to a remote debugger on port 5005:
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Then we set a breakpoint in our code ReportIncidentEndpoint and hit
the SoapUI once again and we are breaked at the breakpoint where we can
inspect the parameters:
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138
Adding a unit test
Oh so much hard work just to hit a webservice, why can't we just use an unit
test to invoke our webservice? Yes of course we can do this, and that's the
next step.
First we create the folder structure src/test/java and src/test/
resources. We then create the unit test in the src/test/java folder.
package org.apache.camel.example.reportincident;
import junit.framework.TestCase;
/**
* Plain JUnit test of our webservice.
*/
public class ReportIncidentEndpointTest extends TestCase {
}
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Here we have a plain old JUnit class. As we want to test webservices we need
to start and expose our webservice in the unit test before we can test it. And
JAXWS has pretty decent methods to help us here, the code is simple as:
import javax.xml.ws.Endpoint;
...
private static String ADDRESS = "http://localhost:9090/unittest";
protected void startServer() throws Exception {
// We need to start a server that exposes or webservice during the unit
testing
// We use jaxws to do this pretty simple
ReportIncidentEndpointImpl server = new ReportIncidentEndpointImpl();
Endpoint.publish(ADDRESS, server);
}
The Endpoint class is the javax.xml.ws.Endpoint that under the covers
looks for a provider and in our case its CXF - so its CXF that does the heavy
lifting of exposing out webservice on the given URL address. Since our class
ReportIncidentEndpointImpl implements the interface
ReportIncidentEndpoint that is decorated with all the jaxws annotations it
got all the information it need to expose the webservice. Below is the CXF
wsdl2java generated interface:
/*
*
*/
package org.apache.camel.example.reportincident;
import
import
import
import
import
import
import
javax.jws.WebMethod;
javax.jws.WebParam;
javax.jws.WebResult;
javax.jws.WebService;
javax.jws.soap.SOAPBinding;
javax.jws.soap.SOAPBinding.ParameterStyle;
javax.xml.bind.annotation.XmlSeeAlso;
/**
* This class was generated by Apache CXF 2.1.1
* Wed Jul 16 12:40:31 CEST 2008
* Generated source version: 2.1.1
*
*/
/*
*
*/
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140
@WebService(targetNamespace = "http://reportincident.example.camel.apache.org", name
= "ReportIncidentEndpoint")
@XmlSeeAlso({ObjectFactory.class})
@SOAPBinding(parameterStyle = SOAPBinding.ParameterStyle.BARE)
public interface ReportIncidentEndpoint {
/*
*
*/
@SOAPBinding(parameterStyle = SOAPBinding.ParameterStyle.BARE)
@WebResult(name = "outputReportIncident", targetNamespace =
"http://reportincident.example.camel.apache.org", partName = "parameters")
@WebMethod(operationName = "ReportIncident", action =
"http://reportincident.example.camel.apache.org/ReportIncident")
public OutputReportIncident reportIncident(
@WebParam(partName = "parameters", name = "inputReportIncident",
targetNamespace = "http://reportincident.example.camel.apache.org")
InputReportIncident parameters
);
}
Next up is to create a webservice client so we can invoke our webservice. For
this we actually use the CXF framework directly as its a bit more easier to
create a client using this framework than using the JAXWS style. We could
have done the same for the server part, and you should do this if you need
more power and access more advanced features.
import org.apache.cxf.jaxws.JaxWsProxyFactoryBean;
...
protected ReportIncidentEndpoint createCXFClient() {
// we use CXF to create a client for us as its easier than JAXWS and works
JaxWsProxyFactoryBean factory = new JaxWsProxyFactoryBean();
factory.setServiceClass(ReportIncidentEndpoint.class);
factory.setAddress(ADDRESS);
return (ReportIncidentEndpoint) factory.create();
}
So now we are ready for creating a unit test. We have the server and the
client. So we just create a plain simple unit test method as the usual junit
style:
public void testRendportIncident() throws Exception {
startServer();
ReportIncidentEndpoint client = createCXFClient();
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InputReportIncident input = new InputReportIncident();
input.setIncidentId("123");
input.setIncidentDate("2008-07-16");
input.setGivenName("Claus");
input.setFamilyName("Ibsen");
input.setSummary("bla bla");
input.setDetails("more bla bla");
input.setEmail("davsclaus@apache.org");
input.setPhone("+45 2962 7576");
OutputReportIncident out = client.reportIncident(input);
assertEquals("Response code is wrong", "OK", out.getCode());
}
Now we are nearly there. But if you run the unit test with mvn test then it
will fail. Why!!! Well its because that CXF needs is missing some
dependencies during unit testing. In fact it needs the web container, so we
need to add this to our pom.xml.
org.apache.cxfcxf-rt-transports-http-jetty${cxf-version}test
Well what is that, CXF also uses Jetty for unit test - well its just shows how
agile, embedable and popular Jetty is.
So lets run our junit test with, and it reports:
mvn test
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] BUILD SUCCESSFUL
Yep thats it for now. We have a basic project setup.
END OF PART 1
Thanks for being patient and reading all this more or less standard Maven,
Spring, JAXWS and Apache CXF stuff. Its stuff that is well covered on the net,
but I wanted a full fledged tutorial on a maven project setup that is web
service ready with Apache CXF. We will use this as a base for the next part
where we demonstrate how Camel can be digested slowly and piece by piece
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142
just as it was back in the times when was introduced and was learning the
Spring framework that we take for granted today.
RESOURCES
• Apache CXF user guide
•
Name
Size
Creator
Creation
Date
ZIP Archive
tutorial_reportincident_partone.zi...
14
kB
Claus
Ibsen
Jul 17,
2008
23:34
Comment
LINKS
▪
▪
▪
▪
▪
▪
Introduction
Part 1
Part 2
Part 3
Part 4
Part 5
PART 2
ADDING CAMEL
In this part we will introduce Camel so we start by adding Camel to our
pom.xml:
...
1.4.0org.apache.camelcamel-core${camel-version}
That's it, only one dependency for now.
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Synchronize IDE
If you continue from part 1, remember to update your editor project
settings since we have introduce new .jar files. For instance IDEA
has a feature to synchronize with Maven projects.
Now we turn towards our webservice endpoint implementation where we
want to let Camel have a go at the input we receive. As Camel is very non
invasive its basically a .jar file then we can just grap Camel but creating a
new instance of DefaultCamelContext that is the hearth of Camel its
context.
CamelContext camel = new DefaultCamelContext();
In fact we create a constructor in our webservice and add this code:
private CamelContext camel;
public ReportIncidentEndpointImpl() throws Exception {
// create the camel context that is the "heart" of Camel
camel = new DefaultCamelContext();
// add the log component
camel.addComponent("log", new LogComponent());
// start Camel
camel.start();
}
LOGGING THE "HELLO WORLD"
Here at first we want Camel to log the givenName and familyName
parameters we receive, so we add the LogComponent with the key log. And
we must start Camel before its ready to act.
Then we change the code in the method that is invoked by Apache CXF when
a webservice request arrives. We get the name and let Camel have a go at it
in the new method we create sendToCamel:
public OutputReportIncident reportIncident(InputReportIncident parameters) {
String name = parameters.getGivenName() + " " + parameters.getFamilyName();
// let Camel do something with the name
sendToCamelLog(name);
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144
Component Documentation
The Log and File components is documented as well, just click on
the links. Just return to this documentation later when you must use
these components for real.
OutputReportIncident out = new OutputReportIncident();
out.setCode("OK");
return out;
}
Next is the Camel code. At first it looks like there are many code lines to do a
simple task of logging the name - yes it is. But later you will in fact realize
this is one of Camels true power. Its concise API. Hint: The same code can be
used for any component in Camel.
private void sendToCamelLog(String name) {
try {
// get the log component
Component component = camel.getComponent("log");
// create an endpoint and configure it.
// Notice the URI parameters this is a common pratice in Camel to
configure
// endpoints based on URI.
// com.mycompany.part2 = the log category used. Will log at INFO level as
default
Endpoint endpoint = component.createEndpoint("log:com.mycompany.part2");
// create an Exchange that we want to send to the endpoint
Exchange exchange = endpoint.createExchange();
// set the in message payload (=body) with the name parameter
exchange.getIn().setBody(name);
// now we want to send the exchange to this endpoint and we then need a
producer
// for this, so we create and start the producer.
Producer producer = endpoint.createProducer();
producer.start();
// process the exchange will send the exchange to the log component, that
will process
// the exchange and yes log the payload
producer.process(exchange);
// stop the producer, we want to be nice and cleanup
producer.stop();
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} catch (Exception e) {
// we ignore any exceptions and just rethrow as runtime
throw new RuntimeException(e);
}
}
Okay there are code comments in the code block above that should explain
what is happening. We run the code by invoking our unit test with maven mvn
test, and we should get this log line:
INFO: Exchange[BodyType:String, Body:Claus Ibsen]
WRITE TO FILE - EASY WITH THE SAME CODE STYLE
Okay that isn't to impressive, Camel can log
Well I promised that the
above code style can be used for any component, so let's store the payload
in a file. We do this by adding the file component to the Camel context
// add the file component
camel.addComponent("file", new FileComponent());
And then we let camel write the payload to the file after we have logged, by
creating a new method sendToCamelFile. We want to store the payload in
filename with the incident id so we need this parameter also:
// let Camel do something with the name
sendToCamelLog(name);
sendToCamelFile(parameters.getIncidentId(), name);
And then the code that is 99% identical. We have change the URI
configuration when we create the endpoint as we pass in configuration
parameters to the file component.
And then we need to set the output filename and this is done by adding a
special header to the exchange. That's the only difference:
private void sendToCamelFile(String incidentId, String name) {
try {
// get the file component
Component component = camel.getComponent("file");
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146
// create an endpoint and configure it.
// Notice the URI parameters this is a common pratice in Camel to
configure
// endpoints based on URI.
// file://target instructs the base folder to output the files. We put in
the target folder
// then its actumatically cleaned by mvn clean
Endpoint endpoint = component.createEndpoint("file://target");
// create an Exchange that we want to send to the endpoint
Exchange exchange = endpoint.createExchange();
// set the in message payload (=body) with the name parameter
exchange.getIn().setBody(name);
// now a special header is set to instruct the file component what the
output filename
// should be
exchange.getIn().setHeader(FileComponent.HEADER_FILE_NAME, "incident-" +
incidentId + ".txt");
// now we want to send the exchange to this endpoint and we then need a
producer
// for this, so we create and start the producer.
Producer producer = endpoint.createProducer();
producer.start();
// process the exchange will send the exchange to the file component,
that will process
// the exchange and yes write the payload to the given filename
producer.process(exchange);
// stop the producer, we want to be nice and cleanup
producer.stop();
} catch (Exception e) {
// we ignore any exceptions and just rethrow as runtime
throw new RuntimeException(e);
}
}
After running our unit test again with mvn test we have a output file in the
target folder:
D:\demo\part-two>type target\incident-123.txt
Claus Ibsen
FULLY JAVA BASED CONFIGURATION OF ENDPOINTS
In the file example above the configuration was URI based. What if you want
100% java setter based style, well this is of course also possible. We just
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need to cast to the component specific endpoint and then we have all the
setters available:
// create the file endpoint, we cast to FileEndpoint because then we can
do
// 100% java settter based configuration instead of the URI sting based
// must pass in an empty string, or part of the URI configuration if
wanted
FileEndpoint endpoint = (FileEndpoint)component.createEndpoint("");
endpoint.setFile(new File("target/subfolder"));
endpoint.setAutoCreate(true);
That's it. Now we have used the setters to configure the FileEndpoint that it
should store the file in the folder target/subfolder. Of course Camel now
stores the file in the subfolder.
D:\demo\part-two>type target\subfolder\incident-123.txt
Claus Ibsen
LESSONS LEARNED
Okay I wanted to demonstrate how you can be in 100% control of the
configuration and usage of Camel based on plain Java code with no hidden
magic or special XML or other configuration files. Just add the camel-core.jar
and you are ready to go.
You must have noticed that the code for sending a message to a given
endpoint is the same for both the log and file, in fact any Camel endpoint.
You as the client shouldn't bother with component specific code such as file
stuff for file components, jms stuff for JMS messaging etc. This is what the
Message Endpoint EIP pattern is all about and Camel solves this very very
nice - a key pattern in Camel.
REDUCING CODE LINES
Now that you have been introduced to Camel and one of its masterpiece
patterns solved elegantly with the Message Endpoint its time to give
productive and show a solution in fewer code lines, in fact we can get it down
to 5, 4, 3, 2 .. yes only 1 line of code.
The key is the ProducerTemplate that is a Spring'ish xxxTemplate based
producer. Meaning that it has methods to send messages to any Camel
endpoints. First of all we need to get hold of such a template and this is done
from the CamelContext
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148
private ProducerTemplate template;
public ReportIncidentEndpointImpl() throws Exception {
...
// get the ProducerTemplate thst is a Spring'ish xxxTemplate based producer
for very
// easy sending exchanges to Camel.
template = camel.createProducerTemplate();
// start Camel
camel.start();
}
Now we can use template for sending payloads to any endpoint in Camel.
So all the logging gabble can be reduced to:
template.sendBody("log:com.mycompany.part2.easy", name);
And the same goes for the file, but we must also send the header to instruct
what the output filename should be:
String filename = "easy-incident-" + incidentId + ".txt";
template.sendBodyAndHeader("file://target/subfolder", name,
FileComponent.HEADER_FILE_NAME, filename);
REDUCING EVEN MORE CODE LINES
Well we got the Camel code down to 1-2 lines for sending the message to the
component that does all the heavy work of wring the message to a file etc.
But we still got 5 lines to initialize Camel.
camel = new DefaultCamelContext();
camel.addComponent("log", new LogComponent());
camel.addComponent("file", new FileComponent());
template = camel.createProducerTemplate();
camel.start();
This can also be reduced. All the standard components in Camel is auto
discovered on-the-fly so we can remove these code lines and we are down to
3 lines.
Okay back to the 3 code lines:
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Component auto discovery
When an endpoint is requested with a scheme that Camel hasn't
seen before it will try to look for it in the classpath. It will do so by
looking for special Camel component marker files that reside in the
folder META-INF/services/org/apache/camel/component. If there
are files in this folder it will read them as the filename is the
scheme part of the URL. For instance the log component is defined
in this file META-INF/services/org/apache/component/log and its
content is:
class=org.apache.camel.component.log.LogComponent
The class property defines the component implementation.
Tip: End-users can create their 3rd party components using the same
technique and have them been auto discovered on-the-fly.
camel = new DefaultCamelContext();
template = camel.createProducerTemplate();
camel.start();
Later will we see how we can reduce this to ... in fact 0 java code lines. But
the 3 lines will do for now.
MESSAGE TRANSLATION
Okay lets head back to the over goal of the integration. Looking at the EIP
diagrams at the introduction page we need to be able to translate the
incoming webservice to an email. Doing so we need to create the email body.
When doing the message translation we could put up our sleeves and do it
manually in pure java with a StringBuilder such as:
private String createMailBody(InputReportIncident parameters) {
StringBuilder sb = new StringBuilder();
sb.append("Incident ").append(parameters.getIncidentId());
sb.append(" has been reported on the ").append(parameters.getIncidentDate());
sb.append(" by ").append(parameters.getGivenName());
sb.append(" ").append(parameters.getFamilyName());
// and the rest of the mail body with more appends to the string builder
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150
return sb.toString();
}
But as always it is a hardcoded template for the mail body and the code gets
kinda ugly if the mail message has to be a bit more advanced. But of course
it just works out-of-the-box with just classes already in the JDK.
Lets use a template language instead such as Apache Velocity. As Camel
have a component for Velocity integration we will use this component.
Looking at the Component List overview we can see that camel-velocity
component uses the artifactId camel-velocity so therefore we need to add
this to the pom.xml
org.apache.camelcamel-velocity${camel-version}
And now we have a Spring conflict as Apache CXF is dependent on Spring
2.0.8 and camel-velocity is dependent on Spring 2.5.5. To remedy this we
could wrestle with the pom.xml with excludes settings in the dependencies
or just bring in another dependency camel-spring:
org.apache.camelcamel-spring${camel-version}
In fact camel-spring is such a vital part of Camel that you will end up using it
in nearly all situations - we will look into how well Camel is seamless
integration with Spring in part 3. For now its just another dependency.
We create the mail body with the Velocity template and create the file
src/main/resources/MailBody.vm. The content in the MailBody.vm file is:
Incident $body.incidentId has been reported on the $body.incidentDate by
$body.givenName $body.familyName.
The person can be contact by:
- email: $body.email
- phone: $body.phone
Summary: $body.summary
Details:
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$body.details
This is an auto generated email. You can not reply.
Letting Camel creating the mail body and storing it as a file is as easy as the
following 3 code lines:
private void generateEmailBodyAndStoreAsFile(InputReportIncident parameters) {
// generate the mail body using velocity template
// notice that we just pass in our POJO (= InputReportIncident) that we
// got from Apache CXF to Velocity.
Object response = template.sendBody("velocity:MailBody.vm", parameters);
// Note: the response is a String and can be cast to String if needed
// store the mail in a file
String filename = "mail-incident-" + parameters.getIncidentId() + ".txt";
template.sendBodyAndHeader("file://target/subfolder", response,
FileComponent.HEADER_FILE_NAME, filename);
}
What is impressive is that we can just pass in our POJO object we got from
Apache CXF to Velocity and it will be able to generate the mail body with this
object in its context. Thus we don't need to prepare anything before we let
Velocity loose and generate our mail body. Notice that the template method
returns a object with out response. This object contains the mail body as a
String object. We can cast to String if needed.
If we run our unit test with mvn test we can in fact see that Camel has
produced the file and we can type its content:
D:\demo\part-two>type target\subfolder\mail-incident-123.txt
Incident 123 has been reported on the 2008-07-16 by Claus Ibsen.
The person can be contact by:
- email: davsclaus@apache.org
- phone: +45 2962 7576
Summary: bla bla
Details:
more bla bla
This is an auto generated email. You can not reply.
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152
FIRST PART OF THE SOLUTION
What we have seen here is actually what it takes to build the first part of the
integration flow. Receiving a request from a webservice, transform it to a
mail body and store it to a file, and return an OK response to the webservice.
All possible within 10 lines of code. So lets wrap it up here is what it takes:
/**
* The webservice we have implemented.
*/
public class ReportIncidentEndpointImpl implements ReportIncidentEndpoint {
private CamelContext camel;
private ProducerTemplate template;
public ReportIncidentEndpointImpl() throws Exception {
// create the camel context that is the "heart" of Camel
camel = new DefaultCamelContext();
// get the ProducerTemplate thst is a Spring'ish xxxTemplate based producer
for very
// easy sending exchanges to Camel.
template = camel.createProducerTemplate();
// start Camel
camel.start();
}
public OutputReportIncident reportIncident(InputReportIncident parameters) {
// transform the request into a mail body
Object mailBody = template.sendBody("velocity:MailBody.vm", parameters);
// store the mail body in a file
String filename = "mail-incident-" + parameters.getIncidentId() + ".txt";
template.sendBodyAndHeader("file://target/subfolder", mailBody,
FileComponent.HEADER_FILE_NAME, filename);
// return an OK reply
OutputReportIncident out = new OutputReportIncident();
out.setCode("OK");
return out;
}
}
Okay I missed by one, its in fact only 9 lines of java code and 2 fields.
END OF PART 2
I know this is a bit different introduction to Camel to how you can start using
it in your projects just as a plain java .jar framework that isn't invasive at all. I
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took you through the coding parts that requires 6 - 10 lines to send a
message to an endpoint, buts it's important to show the Message Endpoint
EIP pattern in action and how its implemented in Camel. Yes of course Camel
also has to one liners that you can use, and will use in your projects for
sending messages to endpoints. This part has been about good old plain
java, nothing fancy with Spring, XML files, auto discovery, OGSi or other new
technologies. I wanted to demonstrate the basic building blocks in Camel and
how its setup in pure god old fashioned Java. There are plenty of eye catcher
examples with one liners that does more than you can imagine - we will
come there in the later parts.
Okay part 3 is about building the last pieces of the solution and now it gets
interesting since we have to wrestle with the event driven consumer.
Brew a cup of coffee, tug the kids and kiss the wife, for now we will have us
some fun with the Camel. See you in part 3.
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LINKS
▪
▪
▪
▪
▪
▪
Introduction
Part 1
Part 2
Part 3
Part 4
Part 5
PART 3
RECAP
Lets just recap on the solution we have now:
public class ReportIncidentEndpointImpl implements ReportIncidentEndpoint {
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154
private CamelContext camel;
private ProducerTemplate template;
public ReportIncidentEndpointImpl() throws Exception {
// create the camel context that is the "heart" of Camel
camel = new DefaultCamelContext();
// get the ProducerTemplate thst is a Spring'ish xxxTemplate based producer
for very
// easy sending exchanges to Camel.
template = camel.createProducerTemplate();
// start Camel
camel.start();
}
/**
* This is the last solution displayed that is the most simple
*/
public OutputReportIncident reportIncident(InputReportIncident parameters) {
// transform the request into a mail body
Object mailBody = template.sendBody("velocity:MailBody.vm", parameters);
// store the mail body in a file
String filename = "mail-incident-" + parameters.getIncidentId() + ".txt";
template.sendBodyAndHeader("file://target/subfolder", mailBody,
FileComponent.HEADER_FILE_NAME, filename);
// return an OK reply
OutputReportIncident out = new OutputReportIncident();
out.setCode("OK");
return out;
}
}
This completes the first part of the solution: receiving the message using
webservice, transform it to a mail body and store it as a text file.
What is missing is the last part that polls the text files and send them as
emails. Here is where some fun starts, as this requires usage of the Event
Driven Consumer EIP pattern to react when new files arrives. So lets see how
we can do this in Camel. There is a saying: Many roads lead to Rome, and
that is also true for Camel - there are many ways to do it in Camel.
ADDING THE EVENT DRIVEN CONSUMER
We want to add the consumer to our integration that listen for new files, we
do this by creating a private method where the consumer code lives. We
must register our consumer in Camel before its started so we need to add,
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and there fore we call the method addMailSenderConsumer in the
constructor below:
public ReportIncidentEndpointImpl() throws Exception {
// create the camel context that is the "heart" of Camel
camel = new DefaultCamelContext();
// get the ProducerTemplate thst is a Spring'ish xxxTemplate based producer
for very
// easy sending exchanges to Camel.
template = camel.createProducerTemplate();
// add the event driven consumer that will listen for mail files and process
them
addMailSendConsumer();
// start Camel
camel.start();
}
The consumer needs to be consuming from an endpoint so we grab the
endpoint from Camel we want to consume. It's file://target/subfolder.
Don't be fooled this endpoint doesn't have to 100% identical to the producer,
i.e. the endpoint we used in the previous part to create and store the files.
We could change the URL to include some options, and to make it more clear
that it's possible we setup a delay value to 10 seconds, and the first poll
starts after 2 seconds. This is done by adding
?consumer.delay=10000&consumer.initialDelay=2000 to the URL.
When we have the endpoint we can create the consumer (just as in part 1
where we created a producer}. Creating the consumer requires a Processor
where we implement the java code what should happen when a message
arrives. To get the mail body as a String object we can use the getBody
method where we can provide the type we want in return.
Sending the email is still left to be implemented, we will do this later. And
finally we must remember to start the consumer otherwise its not active and
won't listen for new files.
private void addMailSendConsumer() throws Exception {
// Grab the endpoint where we should consume. Option - the first poll starts
after 2 seconds
Endpoint endpint = camel.getEndpoint("file://target/
subfolder?consumer.initialDelay=2000");
// create the event driven consumer
// the Processor is the code what should happen when there is an event
// (think it as the onMessage method)
Consumer consumer = endpint.createConsumer(new Processor() {
public void process(Exchange exchange) throws Exception {
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156
URL Configuration
The URL configuration in Camel endpoints is just like regular URL
we know from the Internet. You use ? and & to set the options.
Camel Type Converter
Why don't we just cast it as we always do in Java? Well the biggest
advantage when you provide the type as a parameter you tell
Camel what type you want and Camel can automatically convert it
for you, using its flexible Type Converter mechanism. This is a great
advantage, and you should try to use this instead of regular type
casting.
// get the mail body as a String
String mailBody = exchange.getIn().getBody(String.class);
// okay now we are read to send it as an email
System.out.println("Sending email..." + mailBody);
}
});
// star the consumer, it will listen for files
consumer.start();
}
Before we test it we need to be aware that our unit test is only catering for
the first part of the solution, receiving the message with webservice,
transforming it using Velocity and then storing it as a file - it doesn't test the
Event Driven Consumer we just added. As we are eager to see it in action, we
just do a common trick adding some sleep in our unit test, that gives our
Event Driven Consumer time to react and print to System.out. We will later
refine the test:
public void testRendportIncident() throws Exception {
...
OutputReportIncident out = client.reportIncident(input);
assertEquals("Response code is wrong", "OK", out.getCode());
// give the event driven consumer time to react
Thread.sleep(10 * 1000);
}
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We run the test with mvn clean test and have eyes fixed on the console
output.
During all the output in the console, we see that our consumer has been
triggered, as we want.
2008-07-19 12:09:24,140 [mponent@1f12c4e] DEBUG FileProcessStrategySupport - Locking
the file: target\subfolder\mail-incident-123.txt ...
Sending email...Incident 123 has been reported on the 2008-07-16 by Claus Ibsen.
The person can be contact by:
- email: davsclaus@apache.org
- phone: +45 2962 7576
Summary: bla bla
Details:
more bla bla
This is an auto generated email. You can not reply.
2008-07-19 12:09:24,156 [mponent@1f12c4e] DEBUG FileConsumer - Done processing file:
target\subfolder\mail-incident-123.txt. Status is: OK
SENDING THE EMAIL
Sending the email requires access to a SMTP mail server, but the
implementation code is very simple:
private void sendEmail(String body) {
// send the email to your mail server
String url =
"smtp://someone@localhost?password=secret&to=incident@mycompany.com";
template.sendBodyAndHeader(url, body, "subject", "New incident reported");
}
And just invoke the method from our consumer:
// okay now we are read to send it as an email
System.out.println("Sending email...");
sendEmail(mailBody);
System.out.println("Email sent");
UNIT TESTING MAIL
For unit testing the consumer part we will use a mock mail framework, so we
add this to our pom.xml:
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158
org.jvnet.mock-javamailmock-javamail1.7test
Then we prepare our integration to run with or without the consumer
enabled. We do this to separate the route into the two parts:
▪ receive the webservice, transform and save mail file and return OK
as repose
▪ the consumer that listen for mail files and send them as emails
So we change the constructor code a bit:
public ReportIncidentEndpointImpl() throws Exception {
init(true);
}
public ReportIncidentEndpointImpl(boolean enableConsumer) throws Exception {
init(enableConsumer);
}
private void init(boolean enableConsumer) throws Exception {
// create the camel context that is the "heart" of Camel
camel = new DefaultCamelContext();
// get the ProducerTemplate thst is a Spring'ish xxxTemplate based producer
for very
// easy sending exchanges to Camel.
template = camel.createProducerTemplate();
// add the event driven consumer that will listen for mail files and process
them
if (enableConsumer) {
addMailSendConsumer();
}
// start Camel
camel.start();
}
Then remember to change the ReportIncidentEndpointTest to pass in
false in the ReportIncidentEndpointImpl constructor.
And as always run mvn clean test to be sure that the latest code changes
works.
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ADDING NEW UNIT TEST
We are now ready to add a new unit test that tests the consumer part so we
create a new test class that has the following code structure:
/**
* Plain JUnit test of our consumer.
*/
public class ReportIncidentConsumerTest extends TestCase {
private ReportIncidentEndpointImpl endpoint;
public void testConsumer() throws Exception {
// we run this unit test with the consumer, hence the true parameter
endpoint = new ReportIncidentEndpointImpl(true);
}
}
As we want to test the consumer that it can listen for files, read the file
content and send it as an email to our mailbox we will test it by asserting
that we receive 1 mail in our mailbox and that the mail is the one we expect.
To do so we need to grab the mailbox with the mockmail API. This is done as
simple as:
public void testConsumer() throws Exception {
// we run this unit test with the consumer, hence the true parameter
endpoint = new ReportIncidentEndpointImpl(true);
// get the mailbox
Mailbox box = Mailbox.get("incident@mycompany.com");
assertEquals("Should not have mails", 0, box.size());
How do we trigger the consumer? Well by creating a file in the folder it listen
for. So we could use plain java.io.File API to create the file, but wait isn't there
an smarter solution? ... yes Camel of course. Camel can do amazing stuff in
one liner codes with its ProducerTemplate, so we need to get a hold of this
baby. We expose this template in our ReportIncidentEndpointImpl but adding
this getter:
protected ProducerTemplate getTemplate() {
return template;
}
Then we can use the template to create the file in one code line:
T U T O R IA L S
160
// drop a file in the folder that the consumer listen
// here is a trick to reuse Camel! so we get the producer template and just
// fire a message that will create the file for us
endpoint.getTemplate().sendBodyAndHeader("file://target/
subfolder?append=false", "Hello World",
FileComponent.HEADER_FILE_NAME, "mail-incident-test.txt");
Then we just need to wait a little for the consumer to kick in and do its work
and then we should assert that we got the new mail. Easy as just:
// let the consumer have time to run
Thread.sleep(3 * 1000);
// get the mock mailbox and check if we got mail ;)
assertEquals("Should have got 1 mail", 1, box.size());
assertEquals("Subject wrong", "New incident reported",
box.get(0).getSubject());
assertEquals("Mail body wrong", "Hello World", box.get(0).getContent());
}
The final class for the unit test is:
/**
* Plain JUnit test of our consumer.
*/
public class ReportIncidentConsumerTest extends TestCase {
private ReportIncidentEndpointImpl endpoint;
public void testConsumer() throws Exception {
// we run this unit test with the consumer, hence the true parameter
endpoint = new ReportIncidentEndpointImpl(true);
// get the mailbox
Mailbox box = Mailbox.get("incident@mycompany.com");
assertEquals("Should not have mails", 0, box.size());
// drop a file in the folder that the consumer listen
// here is a trick to reuse Camel! so we get the producer template and just
// fire a message that will create the file for us
endpoint.getTemplate().sendBodyAndHeader("file://target/
subfolder?append=false", "Hello World",
FileComponent.HEADER_FILE_NAME, "mail-incident-test.txt");
// let the consumer have time to run
Thread.sleep(3 * 1000);
// get the mock mailbox and check if we got mail ;)
assertEquals("Should have got 1 mail", 1, box.size());
assertEquals("Subject wrong", "New incident reported",
box.get(0).getSubject());
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assertEquals("Mail body wrong", "Hello World", box.get(0).getContent());
}
}
END OF PART 3
Okay we have reached the end of part 3. For now we have only scratched the
surface of what Camel is and what it can do. We have introduced Camel into
our integration piece by piece and slowly added more and more along the
way. And the most important is: you as the developer never lost control.
We hit a sweet spot in the webservice implementation where we could write
our java code. Adding Camel to the mix is just to use it as a regular java
code, nothing magic. We were in control of the flow, we decided when it was
time to translate the input to a mail body, we decided when the content
should be written to a file. This is very important to not lose control, that the
bigger and heavier frameworks tend to do. No names mentioned, but boy do
developers from time to time dislike these elephants. And Camel is no
elephant.
I suggest you download the samples from part 1 to 3 and try them out. It
is great basic knowledge to have in mind when we look at some of the
features where Camel really excel - the routing domain language.
From part 1 to 3 we touched concepts such as::
▪ Endpoint
▪ URI configuration
▪ Consumer
▪ Producer
▪ Event Driven Consumer
▪ Component
▪ CamelContext
▪ ProducerTemplate
▪ Processor
▪ Type Converter
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T U T O R IA L S
162
LINKS
▪
▪
▪
▪
▪
▪
Introduction
Part 1
Part 2
Part 3
Part 4
Part 5
PART 4
INTRODUCTION
This section is about regular Camel. The examples presented here in this
section is much more in common of all the examples we have in the Camel
documentation.
ROUTING
Camel is particular strong as a light-weight and agile routing and
mediation framework. In this part we will introduce the routing concept
and how we can introduce this into our solution.
Looking back at the figure from the Introduction page we want to implement
this routing. Camel has support for expressing this routing logic using Java as
a DSL (Domain Specific Language). In fact Camel also has DSL for XML and
Scala. In this part we use the Java DSL as its the most powerful and all
developers know Java. Later we will introduce the XML version that is very
well integrated with Spring.
Before we jump into it, we want to state that this tutorial is about
Developers not loosing control. In my humble experience one of the key
fears of developers is that they are forced into a tool/framework where they
loose control and/or power, and the possible is now impossible. So in this
part we stay clear with this vision and our starting point is as follows:
▪ We have generated the webservice source code using the CXF
wsdl2java generator and we have our
ReportIncidentEndpointImpl.java file where we as a Developer feels
home and have the power.
So the starting point is:
/**
* The webservice we have implemented.
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T U T O R IAL S
If you have been reading the previous 3 parts then, this quote
applies:
you must unlearn what you have learned
Master Yoda, Star Wars IV
So we start all over again!
*/
public class ReportIncidentEndpointImpl implements ReportIncidentEndpoint {
/**
* This is the last solution displayed that is the most simple
*/
public OutputReportIncident reportIncident(InputReportIncident parameters) {
// WE ARE HERE !!!
return null;
}
}
Yes we have a simple plain Java class where we have the implementation of
the webservice. The cursor is blinking at the WE ARE HERE block and this is
where we feel home. More or less any Java Developers have implemented
webservices using a stack such as: Apache AXIS, Apache CXF or some other
quite popular framework. They all allow the developer to be in control and
implement the code logic as plain Java code. Camel of course doesn't enforce
this to be any different. Okay the boss told us to implement the solution from
the figure in the Introduction page and we are now ready to code.
RouteBuilder
RouteBuilder is the hearth in Camel of the Java DSL routing. This class does
all the heavy lifting of supporting EIP verbs for end-users to express the
routing. It does take a little while to get settled and used to, but when you
have worked with it for a while you will enjoy its power and realize it is in fact
a little language inside Java itself. Camel is the only integration framework
we are aware of that has Java DSL, all the others are usually only XML based.
As an end-user you usually use the RouteBuilder as of follows:
▪ create your own Route class that extends RouteBuilder
▪ implement your routing DSL in the configure method
So we create a new class ReportIncidentRoutes and implement the first part
of the routing:
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164
import org.apache.camel.builder.RouteBuilder;
public class ReportIncidentRoutes extends RouteBuilder {
public void configure() throws Exception {
// direct:start is a internal queue to kick-start the routing in our example
// we use this as the starting point where you can send messages to
direct:start
from("direct:start")
// to is the destination we send the message to our velocity endpoint
// where we transform the mail body
.to("velocity:MailBody.vm");
}
}
What to notice here is the configure method. Here is where all the action is.
Here we have the Java DSL langauge, that is expressed using the fluent
builder syntax that is also known from Hibernate when you build the
dynamic queries etc. What you do is that you can stack methods separating
with the dot.
In the example above we have a very common routing, that can be
distilled from pseudo verbs to actual code with:
▪ from A to B
▪ From Endpoint A To Endpoint B
▪ from("endpointA").to("endpointB")
▪ from("direct:start").to("velocity:MailBody.vm");
from("direct:start") is the consumer that is kick-starting our routing flow. It
will wait for messages to arrive on the direct queue and then dispatch the
message.
to("velocity:MailBody.vm") is the producer that will receive a message
and let Velocity generate the mail body response.
So what we have implemented so far with our ReportIncidentRoutes
RouteBuilder is this part of the picture:
Adding the RouteBuilder
Now we have our RouteBuilder we need to add/connect it to our
CamelContext that is the hearth of Camel. So turning back to our webservice
implementation class ReportIncidentEndpointImpl we add this constructor to
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the code, to create the CamelContext and add the routes from our route
builder and finally to start it.
private CamelContext context;
public ReportIncidentEndpointImpl() throws Exception {
// create the context
context = new DefaultCamelContext();
// append the routes to the context
context.addRoutes(new ReportIncidentRoutes());
// at the end start the camel context
context.start();
}
Okay how do you use the routes then? Well its just as before we use a
ProducerTemplate to send messages to Endpoints, so we just send to the
direct:start endpoint and it will take it from there.
So we implement the logic in our webservice operation:
/**
* This is the last solution displayed that is the most simple
*/
public OutputReportIncident reportIncident(InputReportIncident parameters) {
Object mailBody = context.createProducerTemplate().sendBody("direct:start",
parameters);
System.out.println("Body:" + mailBody);
// return an OK reply
OutputReportIncident out = new OutputReportIncident();
out.setCode("OK");
return out;
}
Notice that we get the producer template using the
createProducerTemplate method on the CamelContext. Then we send the
input parameters to the direct:start endpoint and it will route it to the
velocity endpoint that will generate the mail body. Since we use direct as
the consumer endpoint (=from) and its a synchronous exchange we will get
the response back from the route. And the response is of course the output
from the velocity endpoint.
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166
About creating ProducerTemplate
In the example above we create a new ProducerTemplate when
the reportIncident method is invoked. However in reality you
should only create the template once and re-use it. See this FAQ
entry.
We have now completed this part of the picture:
UNIT TESTING
Now is the time we would like to unit test what we got now. So we call for
camel and its great test kit. For this to work we need to add it to the pom.xml
org.apache.camelcamel-core1.4.0testtest-jar
After adding it to the pom.xml you should refresh your Java Editor so it
pickups the new jar. Then we are ready to create out unit test class.
We create this unit test skeleton, where we extend this class
ContextTestSupport
package org.apache.camel.example.reportincident;
import org.apache.camel.ContextTestSupport;
import org.apache.camel.builder.RouteBuilder;
/**
* Unit test of our routes
*/
public class ReportIncidentRoutesTest extends ContextTestSupport {
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}
ContextTestSupport is a supporting unit test class for much easier unit
testing with Apache Camel. The class is extending JUnit TestCase itself so you
get all its glory. What we need to do now is to somehow tell this unit test
class that it should use our route builder as this is the one we gonna test. So
we do this by implementing the createRouteBuilder method.
@Override
protected RouteBuilder createRouteBuilder() throws Exception {
return new ReportIncidentRoutes();
}
That is easy just return an instance of our route builder and this unit test will
use our routes.
We then code our unit test method that sends a message to the route and
assert that its transformed to the mail body using the Velocity template.
public void testTransformMailBody() throws Exception {
// create a dummy input with some input data
InputReportIncident parameters = createInput();
// send the message (using the sendBody method that takes a parameters as the
input body)
// to "direct:start" that kick-starts the route
// the response is returned as the out object, and its also the body of the
response
Object out = context.createProducerTemplate().sendBody("direct:start",
parameters);
// convert the response to a string using camel converters. However we could
also have casted it to
// a string directly but using the type converters ensure that Camel can
convert it if it wasn't a string
// in the first place. The type converters in Camel is really powerful and
you will later learn to
// appreciate them and wonder why its not build in Java out-of-the-box
String body = context.getTypeConverter().convertTo(String.class, out);
// do some simple assertions of the mail body
assertTrue(body.startsWith("Incident 123 has been reported on the 2008-07-16
by Claus Ibsen."));
}
/**
* Creates a dummy request to be used for input
*/
protected InputReportIncident createInput() {
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168
It is quite common in Camel itself to unit test using routes defined
as an anonymous inner class, such as illustrated below:
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
public void configure() throws Exception {
// TODO: Add your routes here, such as:
from("jms:queue:inbox").to("file://target/out");
}
};
}
The same technique is of course also possible for end-users of Camel to
create parts of your routes and test them separately in many test classes.
However in this tutorial we test the real route that is to be used for
production, so we just return an instance of the real one.
InputReportIncident input = new InputReportIncident();
input.setIncidentId("123");
input.setIncidentDate("2008-07-16");
input.setGivenName("Claus");
input.setFamilyName("Ibsen");
input.setSummary("bla bla");
input.setDetails("more bla bla");
input.setEmail("davsclaus@apache.org");
input.setPhone("+45 2962 7576");
return input;
}
ADDING THE FILE BACKUP
The next piece of puzzle that is missing is to store the mail body as a backup
file. So we turn back to our route and the EIP patterns. We use the Pipes and
Filters pattern here to chain the routing as:
public void configure() throws Exception {
from("direct:start")
.to("velocity:MailBody.vm")
// using pipes-and-filters we send the output from the previous to the
next
.to("file://target/subfolder");
}
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Notice that we just add a 2nd .to on the newline. Camel will default use the
Pipes and Filters pattern here when there are multi endpoints chained liked
this. We could have used the pipeline verb to let out stand out that its the
Pipes and Filters pattern such as:
from("direct:start")
// using pipes-and-filters we send the output from the previous to the
next
.pipeline("velocity:MailBody.vm", "file://target/subfolder");
But most people are using the multi .to style instead.
We re-run out unit test and verifies that it still passes:
Running org.apache.camel.example.reportincident.ReportIncidentRoutesTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.157 sec
But hey we have added the file producer endpoint and thus a file should also
be created as the backup file. If we look in the target/subfolder we can
see that something happened.
On my humble laptop it created this folder: target\subfolder\ID-clausacer. So the file producer create a sub folder named ID-claus-acer what is
this? Well Camel auto generates an unique filename based on the unique
message id if not given instructions to use a fixed filename. In fact it creates
another sub folder and name the file as: target\subfolder\ID-clausacer\3750-1219148558921\1-0 where 1-0 is the file with the mail body. What
we want is to use our own filename instead of this auto generated filename.
This is archived by adding a header to the message with the filename to use.
So we need to add this to our route and compute the filename based on the
message content.
Setting the filename
For starters we show the simple solution and build from there. We start by
setting a constant filename, just to verify that we are on the right path, to
instruct the file producer what filename to use. The file producer uses a
special header FileComponent.HEADER_FILE_NAME to set the filename.
What we do is to send the header when we "kick-start" the routing as the
header will be propagated from the direct queue to the file producer. What
we need to do is to use the ProducerTemplate.sendBodyAndHeader method
that takes both a body and a header. So we change out webservice code to
include the filename also:
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170
public OutputReportIncident reportIncident(InputReportIncident parameters) {
// create the producer template to use for sending messages
ProducerTemplate producer = context.createProducerTemplate();
// send the body and the filename defined with the special header key
Object mailBody = producer.sendBodyAndHeader("direct:start", parameters,
FileComponent.HEADER_FILE_NAME, "incident.txt");
System.out.println("Body:" + mailBody);
// return an OK reply
OutputReportIncident out = new OutputReportIncident();
out.setCode("OK");
return out;
}
However we could also have used the route builder itself to configure the
constant filename as shown below:
public void configure() throws Exception {
from("direct:start")
.to("velocity:MailBody.vm")
// set the filename to a constant before the file producer receives the
message
.setHeader(FileComponent.HEADER_FILE_NAME, constant("incident.txt"))
.to("file://target/subfolder");
}
But Camel can be smarter and we want to dynamic set the filename based
on some of the input parameters, how can we do this?
Well the obvious solution is to compute and set the filename from the
webservice implementation, but then the webservice implementation has
such logic and we want this decoupled, so we could create our own POJO
bean that has a method to compute the filename. We could then instruct the
routing to invoke this method to get the computed filename. This is a string
feature in Camel, its Bean binding. So lets show how this can be done:
Using Bean Language to compute the filename
First we create our plain java class that computes the filename, and it has
100% no dependencies to Camel what so ever.
/**
* Plain java class to be used for filename generation based on the reported incident
*/
public class FilenameGenerator {
public String generateFilename(InputReportIncident input) {
// compute the filename
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return "incident-" + input.getIncidentId() + ".txt";
}
}
The class is very simple and we could easily create unit tests for it to verify
that it works as expected. So what we want now is to let Camel invoke this
class and its generateFilename with the input parameters and use the output
as the filename. Pheeeww is this really possible out-of-the-box in Camel? Yes
it is. So lets get on with the show. We have the code that computes the
filename, we just need to call it from our route using the Bean Language:
public void configure() throws Exception {
from("direct:start")
// set the filename using the bean language and call the
FilenameGenerator class.
// the 2nd null parameter is optional methodname, to be used to avoid
ambiguity.
// if not provided Camel will try to figure out the best method to
invoke, as we
// only have one method this is very simple
.setHeader(FileComponent.HEADER_FILE_NAME,
BeanLanguage.bean(FilenameGenerator.class, null))
.to("velocity:MailBody.vm")
.to("file://target/subfolder");
}
Notice that we use the bean language where we supply the class with our
bean to invoke. Camel will instantiate an instance of the class and invoke the
suited method. For completeness and ease of code readability we add the
method name as the 2nd parameter
.setHeader(FileComponent.HEADER_FILE_NAME,
BeanLanguage.bean(FilenameGenerator.class, "generateFilename"))
Then other developers can understand what the parameter is, instead of
null.
Now we have a nice solution, but as a sidetrack I want to demonstrate the
Camel has other languages out-of-the-box, and that scripting language is a
first class citizen in Camel where it etc. can be used in content based routing.
However we want it to be used for the filename generation.
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172
Using a script language to set the filename
We could do as in the previous parts where we send the computed
filename as a message header when we "kick-start" the route. But we want
to learn new stuff so we look for a different solution using some of Camels
many Languages. As OGNL is a favorite language of mine (used by
WebWork) so we pick this baby for a Camel ride. For starters we must add
it to our pom.xml:
org.apache.camelcamel-ognl${camel-version}
And remember to refresh your editor so you got the new .jars.
We want to construct the filename based on this syntax: mail-incident#ID#.txt where #ID# is the incident id from the input parameters. As
OGNL is a language that can invoke methods on bean we can invoke the
getIncidentId() on the message body and then concat it with the fixed
pre and postfix strings.
In OGNL glory this is done as:
"'mail-incident-' + request.body.incidentId + '.txt'"
where request.body.incidentId computes to:
▪ request is the IN message. See the OGNL for other
predefined objects available
▪ body is the body of the in message
▪ incidentId will invoke the getIncidentId() method on the
body.
The rest is just more or less regular plain code where we
can concat strings.
Now we got the expression to dynamic compute the filename on the fly we
need to set it on our route so we turn back to our route, where we can add
the OGNL expression:
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public void configure() throws Exception {
from("direct:start")
// we need to set the filename and uses OGNL for this
.setHeader(FileComponent.HEADER_FILE_NAME,
OgnlExpression.ognl("'mail-incident-' + request.body.incidentId + '.txt'"))
// using pipes-and-filters we send the output from the previous
to the next
.pipeline("velocity:MailBody.vm", "file://target/subfolder");
}
And since we are on Java 1.5 we can use the static import of ognl so we
have:
import static org.apache.camel.language.ognl.OgnlExpression.ognl;
...
.setHeader(FileComponent.HEADER_FILE_NAME, ognl("'mail-incident-' +
request.body.incidentId + '.txt'"))
Notice the import static also applies for all the other languages, such as the
Bean Language we used previously.
Whatever worked for you we have now implemented the backup of the data
files:
SENDING THE EMAIL
What we need to do before the solution is completed is to actually send the
email with the mail body we generated and stored as a file. In the previous
part we did this with a File consumer, that we manually added to the
CamelContext. We can do this quite easily with the routing.
import org.apache.camel.builder.RouteBuilder;
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174
public class ReportIncidentRoutes extends RouteBuilder {
public void configure() throws Exception {
// first part from the webservice -> file backup
from("direct:start")
.setHeader(FileComponent.HEADER_FILE_NAME, bean(FilenameGenerator.class,
"generateFilename"))
.to("velocity:MailBody.vm")
.to("file://target/subfolder");
// second part from the file backup -> send email
from("file://target/subfolder")
// set the subject of the email
.setHeader("subject", constant("new incident reported"))
// send the email
.to("smtp://someone@localhost?password=secret&to=incident@mycompany.com");
}
}
The last 3 lines of code does all this. It adds a file consumer
from("file://target/subfolder"), sets the mail subject, and finally send it as
an email.
The DSL is really powerful where you can express your routing integration
logic.
So we completed the last piece in the picture puzzle with just 3 lines of code.
We have now completed the integration:
CONCLUSION
We have just briefly touched the routing in Camel and shown how to
implement them using the fluent builder syntax in Java. There is much
more to the routing in Camel than shown here, but we are learning step by
step. We continue in part 5. See you there.
RESOURCES
•
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Name
Size
Creator
Creation
Date
ZIP Archive partfour.zip
11
kB
Claus
Ibsen
Aug 25, 2008
07:24
Comment
LINKS
▪
▪
▪
▪
▪
▪
Introduction
Part 1
Part 2
Part 3
Part 4
Part 5
BETTER JMS TRANSPORT FOR CXF WEBSERVICE USING
APACHE CAMEL
Configuring JMS in Apache CXF before Version 2.1.3 is possible but not really
easy or nice. This article shows how to use Apache Camel to provide a better
JMS Transport for CXF.
Update: Since CXF 2.1.3 there is a new way of configuring JMS (Using the
JMSConfigFeature). It makes JMS config for CXF as easy as with Camel. Using
Camel for JMS is still a good idea if you want to use the rich feature of Camel
for routing and other Integration Scenarios that CXF does not support.
You can find the original announcement for this Tutorial and some
additional info on Christian Schneider´s Blog
So how to connect Apache Camel and CXF
The best way to connect Camel and CXF is using the Camel transport for
CXF. This is a camel module that registers with cxf as a new transport. It is
quite easy to configure.
http://cxf.apache.org/transports/camel
T U T O R IA L S
176
This bean registers with CXF and provides a new transport prefix camel://
that can be used in CXF address configurations. The bean references a bean
cxf which will be already present in your config. The other refrenceis a camel
context. We will later define this bean to provide the routing config.
How is JMS configured in Camel
In camel you need two things to configure JMS. A ConnectionFactory and a
JMSComponent. As ConnectionFactory you can simply set up the normal
Factory your JMS provider offers or bind a JNDI ConnectionFactory. In this
example we use the ConnectionFactory provided by ActiveMQ.
Then we set up the JMSComponent. It offers a new transport prefix to camel
that we simply call jms. If we need several JMSComponents we can
differentiate them by their name.
You can find more details about the JMSComponent at the Camel Wiki. For
example you find the complete configuration options and a JNDI sample
there.
Setting up the CXF client
We will configure a simple CXF webservice client. It will use stub code
generated from a wsdl. The webservice client will be configured to use JMS
directly. You can also use a direct: Endpoint and do the routing to JMS in the
Camel Context.
We explicitly configure serviceName and endpointName so they are not read
from the wsdl. The names we use are arbitrary and have no further function
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T U T O R IAL S
but we set them to look nice. The serviceclass points to the service interface
that was generated from the wsdl. Now the important thing is address. Here
we tell cxf to use the camel transport, use the JmsComponent who registered
the prefix "jms" and use the queue "CustomerService".
Setting up the CamelContext
As we do not need additional routing an empty CamelContext bean will
suffice.
Running the Example
• Download the example project here
• Follow the readme.txt
Conclusion
As you have seen in this example you can use Camel to connect services to
JMS easily while being able to also use the rich integration features of Apache
Camel.
TUTORIAL USING AXIS 1.4 WITH APACHE CAMEL
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Tutorial using Axis 1.4 with Apache Camel
Prerequisites
Distribution
Introduction
Setting up the project to run Axis
Maven 2
wsdl
Configuring Axis
Running the Example
Integrating Spring
Using Spring
Integrating Camel
CamelContext
Store a file backup
Running the example
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178
Removed from distribution
This example has been removed from Camel 2.9 onwards. Apache
Axis 1.4 is a very old and unsupported framework. We encourage
users to use CXF instead of Axis.
•
•
•
•
•
•
Unit Testing
Smarter Unit Testing with Spring
Unit Test calling WebService
Annotations
The End
See Also
Prerequisites
This tutorial uses Maven 2 to setup the Camel project and for dependencies
for artifacts.
Distribution
This sample is distributed with the Camel 1.5 distribution as examples/
camel-example-axis.
Introduction
Apache Axis is/was widely used as a webservice framework. So in line with
some of the other tutorials to demonstrate how Camel is not an invasive
framework but is flexible and integrates well with existing solution.
We have an existing solution that exposes a webservice using Axis 1.4
deployed as web applications. This is a common solution. We use contract
first so we have Axis generated source code from an existing wsdl file. Then
we show how we introduce Spring and Camel to integrate with Axis.
This tutorial uses the following frameworks:
• Maven 2.0.9
• Apache Camel 1.5.0
• Apache Axis 1.4
• Spring 2.5.5
Setting up the project to run Axis
This first part is about getting the project up to speed with Axis. We are not
touching Camel or Spring at this time.
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T U T O R IAL S
Maven 2
Axis dependencies is available for maven 2 so we configure our pom.xml as:
org.apache.axisaxis1.4org.apache.axisaxis-jaxrpc1.4org.apache.axisaxis-saaj1.4axisaxis-wsdl4j1.5.1commons-discoverycommons-discovery0.4log4jlog4j1.2.14
Then we need to configure maven to use Java 1.5 and the Axis maven plugin
that generates the source code based on the wsdl file:
org.apache.maven.pluginsmaven-compiler-plugin1.51.5
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180
org.codehaus.mojoaxistools-maven-pluginsrc/main/resources/com.mycompany.myschemafalsetruefalsewsdl2java
wsdl
We use the same .wsdl file as the Tutorial-Example-ReportIncident and copy
it to src/main/webapp/WEB-INF/wsdl
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182
Configuring Axis
Okay we are now setup for the contract first development and can generate
the source file. For now we are still only using standard Axis and not Spring
nor Camel. We still need to setup Axis as a web application so we configure
the web.xml in src/main/webapp/WEB-INF/web.xml as:
axisorg.apache.axis.transport.http.AxisServletaxis/services/*
The web.xml just registers Axis servlet that is handling the incoming web
requests to its servlet mapping. We still need to configure Axis itself and this
is done using its special configuration file server-config.wsdd. We nearly
get this file for free if we let Axis generate the source code so we run the
maven goal:
mvn axistools:wsdl2java
The tool will generate the source code based on the wsdl and save the files
to the following folder:
.\target\generated-sources\axistools\wsdl2java\org\apache\camel\example\reportincident
deploy.wsdd
InputReportIncident.java
OutputReportIncident.java
ReportIncidentBindingImpl.java
ReportIncidentBindingStub.java
ReportIncidentService_PortType.java
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ReportIncidentService_Service.java
ReportIncidentService_ServiceLocator.java
undeploy.wsdd
This is standard Axis and so far no Camel or Spring has been touched. To
implement our webservice we will add our code, so we create a new class
AxisReportIncidentService that implements the port type interface where
we can implement our code logic what happens when the webservice is
invoked.
package org.apache.camel.example.axis;
import org.apache.camel.example.reportincident.InputReportIncident;
import org.apache.camel.example.reportincident.OutputReportIncident;
import org.apache.camel.example.reportincident.ReportIncidentService_PortType;
import java.rmi.RemoteException;
/**
* Axis webservice
*/
public class AxisReportIncidentService implements ReportIncidentService_PortType {
public OutputReportIncident reportIncident(InputReportIncident parameters) throws
RemoteException {
System.out.println("Hello AxisReportIncidentService is called from " +
parameters.getGivenName());
OutputReportIncident out = new OutputReportIncident();
out.setCode("OK");
return out;
}
}
Now we need to configure Axis itself and this is done using its serverconfig.wsdd file. We nearly get this for for free from the auto generated
code, we copy the stuff from deploy.wsdd and made a few modifications:
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The globalConfiguration and transport is not in the deploy.wsdd file so
you gotta write that yourself. The service is a 100% copy from deploy.wsdd.
Axis has more configuration to it than shown here, but then you should check
the Axis documentation.
What we need to do now is important, as we need to modify the above
configuration to use our webservice class than the default one, so we change
the classname parameter to our class AxisReportIncidentService:
Running the Example
Now we are ready to run our example for the first time, so we use Jetty as
the quick web container using its maven command:
mvn jetty:run
Then we can hit the web browser and enter this URL:
http://localhost:8080/camel-example-axis/services and you should
see the famous Axis start page with the text And now... Some Services.
Clicking on the .wsdl link shows the wsdl file, but what. It's an auto
generated one and not our original .wsdl file. So we need to fix this ASAP and
this is done by configuring Axis in the server-config.wsdd file:
/WEB-INF/wsdl/report_incident.wsdl
...
We do this by adding the wsdlFile tag in the service element where we can
point to the real .wsdl file.
Integrating Spring
First we need to add its dependencies to the pom.xml.
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186
org.springframeworkspring-web2.5.5
Spring is integrated just as it would like to, we add its listener to the web.xml
and a context parameter to be able to configure precisely what spring xml
files to use:
contextConfigLocation
classpath:axis-example-context.xml
org.springframework.web.context.ContextLoaderListener
Next is to add a plain spring XML file named axis-example-context.xml in
the src/main/resources folder.
The spring XML file is currently empty. We hit jetty again with mvn jetty:run
just to make sure Spring was setup correctly.
Using Spring
We would like to be able to get hold of the Spring ApplicationContext from
our webservice so we can get access to the glory spring, but how do we do
this? And our webservice class AxisReportIncidentService is created and
managed by Axis we want to let Spring do this. So we have two problems.
We solve these problems by creating a delegate class that Axis creates,
and this delegate class gets hold on Spring and then gets our real webservice
as a spring bean and invoke the service.
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First we create a new class that is 100% independent from Axis and just a
plain POJO. This is our real service.
package org.apache.camel.example.axis;
import org.apache.camel.example.reportincident.InputReportIncident;
import org.apache.camel.example.reportincident.OutputReportIncident;
/**
* Our real service that is not tied to Axis
*/
public class ReportIncidentService {
public OutputReportIncident reportIncident(InputReportIncident parameters) {
System.out.println("Hello ReportIncidentService is called from " +
parameters.getGivenName());
OutputReportIncident out = new OutputReportIncident();
out.setCode("OK");
return out;
}
}
So now we need to get from AxisReportIncidentService to this one
ReportIncidentService using Spring. Well first of all we add our real service to
spring XML configuration file so Spring can handle its lifecycle:
And then we need to modify AxisReportIncidentService to use Spring to
lookup the spring bean id="incidentservice" and delegate the call. We do
this by extending the spring class
org.springframework.remoting.jaxrpc.ServletEndpointSupport so the
refactored code is:
package org.apache.camel.example.axis;
import org.apache.camel.example.reportincident.InputReportIncident;
import org.apache.camel.example.reportincident.OutputReportIncident;
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188
import org.apache.camel.example.reportincident.ReportIncidentService_PortType;
import org.springframework.remoting.jaxrpc.ServletEndpointSupport;
import java.rmi.RemoteException;
/**
* Axis webservice
*/
public class AxisReportIncidentService extends ServletEndpointSupport implements
ReportIncidentService_PortType {
public OutputReportIncident reportIncident(InputReportIncident parameters) throws
RemoteException {
// get hold of the spring bean from the application context
ReportIncidentService service = (ReportIncidentService)
getApplicationContext().getBean("incidentservice");
// delegate to the real service
return service.reportIncident(parameters);
}
}
To see if everything is okay we run mvn jetty:run.
In the code above we get hold of our service at each request by looking up
in the application context. However Spring also supports an init method
where we can do this once. So we change the code to:
public class AxisReportIncidentService extends ServletEndpointSupport implements
ReportIncidentService_PortType {
private ReportIncidentService service;
@Override
protected void onInit() throws ServiceException {
// get hold of the spring bean from the application context
service = (ReportIncidentService)
getApplicationContext().getBean("incidentservice");
}
public OutputReportIncident reportIncident(InputReportIncident parameters) throws
RemoteException {
// delegate to the real service
return service.reportIncident(parameters);
}
}
So now we have integrated Axis with Spring and we are ready for Camel.
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Integrating Camel
Again the first step is to add the dependencies to the maven pom.xml file:
org.apache.camelcamel-core1.5.0org.apache.camelcamel-spring1.5.0
Now that we have integrated with Spring then we easily integrate with Camel
as Camel works well with Spring.
We choose to integrate Camel in the Spring XML file so we add the camel
namespace and the schema location:
xmlns:camel="http://activemq.apache.org/camel/schema/spring"
http://activemq.apache.org/camel/schema/spring http://activemq.apache.org/camel/
schema/spring/camel-spring.xsd"
CamelContext
CamelContext is the heart of Camel its where all the routes, endpoints,
components, etc. is registered. So we setup a CamelContext and the spring
XML files looks like:
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Camel does not require Spring
Camel does not require Spring, we could easily have used Camel
without Spring, but most users prefer to use Spring also.
Store a file backup
We want to store the web service request as a file before we return a
response. To do this we want to send the file content as a message to an
endpoint that produces the file. So we need to do two steps:
▪ configure the file backup endpoint
▪ send the message to the endpoint
The endpoint is configured in spring XML so we just add it as:
In the CamelContext we have defined our endpoint with the id backup and
configured it use the URL notation that we know from the internet. Its a file
scheme that accepts a context and some options. The contest is target and
its the folder to store the file. The option is just as the internet with ? and &
for subsequent options. We configure it to not append, meaning than any
existing file will be overwritten. See the File component for options and how
to use the camel file endpoint.
Next up is to be able to send a message to this endpoint. The easiest way
is to use a ProducerTemplate. A ProducerTemplate is inspired by Spring
template pattern with for instance JmsTemplate or JdbcTemplate in mind. The
template that all the grunt work and exposes a simple interface to the enduser where he/she can set the payload to send. Then the template will do
proper resource handling and all related issues in that regard. But how do we
get hold of such a template? Well the CamelContext is able to provide one.
This is done by configuring the template on the camel context in the spring
XML as:
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Then we can expose a ProducerTemplate property on our service with a
setter in the Java code as:
public class ReportIncidentService {
private ProducerTemplate template;
public void setTemplate(ProducerTemplate template) {
this.template = template;
}
And then let Spring handle the dependency inject as below:
Now we are ready to use the producer template in our service to send the
payload to the endpoint. The template has many sendXXX methods for this
purpose. But before we send the payload to the file endpoint we must also
specify what filename to store the file as. This is done by sending meta data
with the payload. In Camel metadata is sent as headers. Headers is just a
plain Map. So if we needed to send several metadata then
we could construct an ordinary HashMap and put the values in there. But as
we just need to send one header with the filename Camel has a convenient
send method sendBodyAndHeader so we choose this one.
public OutputReportIncident reportIncident(InputReportIncident parameters) {
System.out.println("Hello ReportIncidentService is called from " +
parameters.getGivenName());
String data = parameters.getDetails();
// store the data as a file
String filename = parameters.getIncidentId() + ".txt";
// send the data to the endpoint and the header contains what filename it
should be stored as
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template.sendBodyAndHeader("backup", data, "org.apache.camel.file.name",
filename);
OutputReportIncident out = new OutputReportIncident();
out.setCode("OK");
return out;
}
The template in the code above uses 4 parameters:
▪ the endpoint name, in this case the id referring to the endpoint
defined in Spring XML in the camelContext element.
▪ the payload, can be any kind of object
▪ the key for the header, in this case a Camel keyword to set the
filename
▪ and the value for the header
Running the example
We start our integration with maven using mvn jetty:run. Then we open a
browser and hit http://localhost:8080. Jetty is so smart that it display a
frontpage with links to the deployed application so just hit the link and you
get our application. Now we hit append /services to the URL to access the
Axis frontpage. The URL should be http://localhost:8080/camelexample-axis/services.
You can then test it using a web service test tools such as SoapUI.
Hitting the service will output to the console
2008-09-06 15:01:41.718::INFO: Started SelectChannelConnector @ 0.0.0.0:8080
[INFO] Started Jetty Server
Hello ReportIncidentService is called from Ibsen
And there should be a file in the target subfolder.
dir target /b
123.txt
Unit Testing
We would like to be able to unit test our ReportIncidentService class. So
we add junit to the maven dependency:
junit
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junit3.8.2test
And then we create a plain junit testcase for our service class.
package org.apache.camel.example.axis;
import junit.framework.TestCase;
import org.apache.camel.example.reportincident.InputReportIncident;
import org.apache.camel.example.reportincident.OutputReportIncident;
/**
* Unit test of service
*/
public class ReportIncidentServiceTest extends TestCase {
public void testIncident() {
ReportIncidentService service = new ReportIncidentService();
InputReportIncident input = createDummyIncident();
OutputReportIncident output = service.reportIncident(input);
assertEquals("OK", output.getCode());
}
protected InputReportIncident createDummyIncident() {
InputReportIncident input = new InputReportIncident();
input.setEmail("davsclaus@apache.org");
input.setIncidentId("12345678");
input.setIncidentDate("2008-07-13");
input.setPhone("+45 2962 7576");
input.setSummary("Failed operation");
input.setDetails("The wrong foot was operated.");
input.setFamilyName("Ibsen");
input.setGivenName("Claus");
return input;
}
}
Then we can run the test with maven using: mvn test. But we will get a
failure:
Running org.apache.camel.example.axis.ReportIncidentServiceTest
Hello ReportIncidentService is called from Claus
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.235 sec <<< FAILURE!
Results :
Tests in error:
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testIncident(org.apache.camel.example.axis.ReportIncidentServiceTest)
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0
What is the problem? Well our service uses a CamelProducer (the template)
to send a message to the file endpoint so the message will be stored in a file.
What we need is to get hold of such a producer and inject it on our service,
by calling the setter.
Since Camel is very light weight and embedable we are able to create a
CamelContext and add the endpoint in our unit test code directly. We do this
to show how this is possible:
private CamelContext context;
@Override
protected void setUp() throws Exception {
super.setUp();
// CamelContext is just created like this
context = new DefaultCamelContext();
// then we can create our endpoint and set the options
FileEndpoint endpoint = new FileEndpoint();
// the endpoint must have the camel context set also
endpoint.setCamelContext(context);
// our output folder
endpoint.setFile(new File("target"));
// and the option not to append
endpoint.setAppend(false);
// then we add the endpoint just in java code just as the spring XML, we
register it with the "backup" id.
context.addSingletonEndpoint("backup", endpoint);
// finally we need to start the context so Camel is ready to rock
context.start();
}
@Override
protected void tearDown() throws Exception {
super.tearDown();
// and we are nice boys so we stop it to allow resources to clean up
context.stop();
}
So now we are ready to set the ProducerTemplate on our service, and we get
a hold of that baby from the CamelContext as:
public void testIncident() {
ReportIncidentService service = new ReportIncidentService();
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// get a producer template from the camel context
ProducerTemplate template = context.createProducerTemplate();
// inject it on our service using the setter
service.setTemplate(template);
InputReportIncident input = createDummyIncident();
OutputReportIncident output = service.reportIncident(input);
assertEquals("OK", output.getCode());
}
And this time when we run the unit test its a success:
Results :
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
We would like to test that the file exists so we add these two lines to our test
method:
// should generate a file also
File file = new File("target/" + input.getIncidentId() + ".txt");
assertTrue("File should exists", file.exists());
Smarter Unit Testing with Spring
The unit test above requires us to assemble the Camel pieces manually in
java code. What if we would like our unit test to use our spring configuration
file axis-example-context.xml where we already have setup the endpoint.
And of course we would like to test using this configuration file as this is the
real file we will use. Well hey presto the xml file is a spring
ApplicationContext file and spring is able to load it, so we go the spring path
for unit testing. First we add the spring-test jar to our maven dependency:
org.springframeworkspring-testtest
And then we refactor our unit test to be a standard spring unit class. What
we need to do is to extend AbstractJUnit38SpringContextTests instead of
TestCase in our unit test. Since Spring 2.5 embraces annotations we will use
one as well to instruct what our xml configuration file is located:
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196
@ContextConfiguration(locations = "classpath:axis-example-context.xml")
public class ReportIncidentServiceTest extends AbstractJUnit38SpringContextTests {
What we must remember to add is the classpath: prefix as our xml file is
located in src/main/resources. If we omit the prefix then Spring will by
default try to locate the xml file in the current package and that is
org.apache.camel.example.axis. If the xml file is located outside the
classpath you can use file: prefix instead. So with these two modifications we
can get rid of all the setup and teardown code we had before and now we will
test our real configuration.
The last change is to get hold of the producer template and now we can
just refer to the bean id it has in the spring xml file:
So we get hold of it by just getting it from the spring ApplicationContext as
all spring users is used to do:
// get a producer template from the the spring context
ProducerTemplate template = (ProducerTemplate)
applicationContext.getBean("camelTemplate");
// inject it on our service using the setter
service.setTemplate(template);
Now our unit test is much better, and a real power of Camel is that is fits
nicely with Spring and you can use standard Spring'ish unit test to test your
Camel applications as well.
Unit Test calling WebService
What if you would like to execute a unit test where you send a webservice
request to the AxisReportIncidentService how do we unit test this one?
Well first of all the code is merely just a delegate to our real service that we
have just tested, but nevertheless its a good question and we would like to
know how. Well the answer is that we can exploit that fact that Jetty is also a
slim web container that can be embedded anywhere just as Camel can. So
we add this to our pom.xml:
org.mortbay.jettyjetty${jetty-version}
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test
Then we can create a new class AxisReportIncidentServiceTest to unit
test with Jetty. The code to setup Jetty is shown below with code comments:
public class AxisReportIncidentServiceTest extends TestCase {
private Server server;
private void startJetty() throws Exception {
// create an embedded Jetty server
server = new Server();
// add a listener on port 8080 on localhost (127.0.0.1)
Connector connector = new SelectChannelConnector();
connector.setPort(8080);
connector.setHost("127.0.0.1");
server.addConnector(connector);
// add our web context path
WebAppContext wac = new WebAppContext();
wac.setContextPath("/unittest");
// set the location of the exploded webapp where WEB-INF is located
// this is a nice feature of Jetty where we can point to src/main/webapp
wac.setWar("./src/main/webapp");
server.setHandler(wac);
// then start Jetty
server.setStopAtShutdown(true);
server.start();
}
@Override
protected void setUp() throws Exception {
super.setUp();
startJetty();
}
@Override
protected void tearDown() throws Exception {
super.tearDown();
server.stop();
}
}
Now we just need to send the incident as a webservice request using Axis. So
we add the following code:
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public void testReportIncidentWithAxis() throws Exception {
// the url to the axis webservice exposed by jetty
URL url = new URL("http://localhost:8080/unittest/services/
ReportIncidentPort");
// Axis stuff to get the port where we can send the webservice request
ReportIncidentService_ServiceLocator locator = new
ReportIncidentService_ServiceLocator();
ReportIncidentService_PortType port = locator.getReportIncidentPort(url);
// create input to send
InputReportIncident input = createDummyIncident();
// send the webservice and get the response
OutputReportIncident output = port.reportIncident(input);
assertEquals("OK", output.getCode());
// should generate a file also
File file = new File("target/" + input.getIncidentId() + ".txt");
assertTrue("File should exists", file.exists());
}
protected InputReportIncident createDummyIncident() {
InputReportIncident input = new InputReportIncident();
input.setEmail("davsclaus@apache.org");
input.setIncidentId("12345678");
input.setIncidentDate("2008-07-13");
input.setPhone("+45 2962 7576");
input.setSummary("Failed operation");
input.setDetails("The wrong foot was operated.");
input.setFamilyName("Ibsen");
input.setGivenName("Claus");
return input;
}
And now we have an unittest that sends a webservice request using good old
Axis.
Annotations
Both Camel and Spring has annotations that can be used to configure and
wire trivial settings more elegantly. Camel has the endpoint annotation
@EndpointInjected that is just what we need. With this annotation we can
inject the endpoint into our service. The annotation takes either a name or
uri parameter. The name is the bean id in the Registry. The uri is the URI
configuration for the endpoint. Using this you can actually inject an endpoint
that you have not defined in the camel context. As we have defined our
endpoint with the id backup we use the name parameter.
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@EndpointInject(name = "backup")
private ProducerTemplate template;
Camel is smart as @EndpointInjected supports different kinds of object
types. We like the ProducerTemplate so we just keep it as it is.
Since we use annotations on the field directly we do not need to set the
property in the spring xml file so we change our service bean:
Running the unit test with mvn test reveals that it works nicely.
And since we use the @EndpointInjected that refers to the endpoint with
the id backup directly we can loose the template tag in the xml, so its
shorter:
And the final touch we can do is that since the endpoint is injected with
concrete endpoint to use we can remove the "backup" name parameter
when we send the message. So we change from:
// send the data to the endpoint and the header contains what filename it
should be stored as
template.sendBodyAndHeader("backup", data, "org.apache.camel.file.name",
filename);
To without the name:
// send the data to the endpoint and the header contains what filename it
should be stored as
template.sendBodyAndHeader(data, "org.apache.camel.file.name", filename);
Then we avoid to duplicate the name and if we rename the endpoint name
then we don't forget to change it in the code also.
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The End
This tutorial hasn't really touched the one of the key concept of Camel as a
powerful routing and mediation framework. But we wanted to demonstrate
its flexibility and that it integrates well with even older frameworks such as
Apache Axis 1.4.
Check out the other tutorials on Camel and the other examples.
Note that the code shown here also applies to Camel 1.4 so actually you
can get started right away with the released version of Camel. As this time of
writing Camel 1.5 is work in progress.
See Also
▪ Tutorials
▪ Examples
TUTORIAL ON USING CAMEL IN A WEB APPLICATION
Camel has been designed to work great with the Spring framework; so if you
are already a Spring user you can think of Camel as just a framework for
adding to your Spring XML files.
So you can follow the usual Spring approach to working with web
applications; namely to add the standard Spring hook to load a /WEB-INF/
applicationContext.xml file. In that file you can include your usual Camel
XML configuration.
Step1: Edit your web.xml
To enable spring add a context loader listener to your /WEB-INF/web.xml
file
org.springframework.web.context.ContextLoaderListener
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This will cause Spring to boot up and look for the /WEB-INF/
applicationContext.xml file.
Step 2: Create a /WEB-INF/applicationContext.xml file
Now you just need to create your Spring XML file and add your camel routes
or configuration.
For example
Then boot up your web application and you're good to go!
Hints and Tips
If you use Maven to build your application your directory tree will look like
this...
src/main/webapp/WEB-INF
web.xml
applicationContext.xml
You should update your Maven pom.xml to enable WAR packaging/naming
like this...
...
war
...
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[desired WAR file name]
...
To enable more rapid development we highly recommend the jetty:run
maven plugin.
Please refer to the help for more information on using jetty:run - but briefly
if you add the following to your pom.xml
org.mortbay.jettymaven-jetty-plugin/10
Then you can run your web application as follows
mvn jetty:run
Then Jetty will also monitor your target/classes directory and your src/main/
webapp directory so that if you modify your spring XML, your web.xml or
your java code the web application will be restarted, re-creating your Camel
routes.
If your unit tests take a while to run, you could miss them out when
running your web application via
mvn -Dtest=false jetty:run
TUTORIAL BUSINESS PARTNERS
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Under Construction
This tutorial is a work in progress.
BACKGROUND AND INTRODUCTION
Business Background
So there's a company, which we'll call Acme. Acme sells widgets, in a fairly
unusual way. Their customers are responsible for telling Acme what they
purchased. The customer enters into their own systems (ERP or whatever)
which widgets they bought from Acme. Then at some point, their systems
emit a record of the sale which needs to go to Acme so Acme can bill them
for it. Obviously, everyone wants this to be as automated as possible, so
there needs to be integration between the customer's system and Acme.
Sadly, Acme's sales people are, technically speaking, doormats. They tell
all their prospects, "you can send us the data in whatever format, using
whatever protocols, whatever. You just can't change once it's up and
running."
The result is pretty much what you'd expect. Taking a random sample of 3
customers:
• Customer 1: XML over FTP
• Customer 2: CSV over HTTP
• Customer 3: Excel via e-mail
Now on the Acme side, all this has to be converted to a canonical XML format
and submitted to the Acme accounting system via JMS. Then the Acme
accounting system does its stuff and sends an XML reply via JMS, with a
summary of what it processed (e.g. 3 line items accepted, line item #2 in
error, total invoice $123.45). Finally, that data needs to be formatted into an
e-mail, and sent to a contact at the customer in question ("Dear Joyce, we
received an invoice on 1/2/08. We accepted 3 line items totaling $123.45,
though there was an error with line items #2 [invalid quantity ordered].
Thank you for your business. Love, Acme.").
So it turns out Camel can handle all this:
• Listen for HTTP, e-mail, and FTP files
• Grab attachments from the e-mail messages
• Convert XML, XLS, and CSV files to a canonical XML format
• read and write JMS messages
• route based on company ID
• format e-mails using Velocity templates
• send outgoing e-mail messages
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Tutorial Background
This tutorial will cover all that, plus setting up tests along the way.
Before starting, you should be familiar with:
• Camel concepts including the CamelContext, Routes, Components
and Endpoints, and Enterprise Integration Patterns
• Configuring Camel with the XML or Java DSL
You'll learn:
• How to set up a Maven build for a Camel project
• How to transform XML, CSV, and Excel data into a standard XML
format with Camel
◦ How to write POJOs (Plain Old Java Objects), Velocity
templates, and XSLT stylesheets that are invoked by Camel
routes for message transformation
• How to configure simple and complex Routes in Camel, using either
the XML or the Java DSL format
• How to set up unit tests that load a Camel configuration and test
Camel routes
• How to use Camel's Data Formats to automatically convert data
between Java objects and XML, CSV files, etc.
• How to send and receive e-mail from Camel
• How to send and receive JMS messages from Camel
• How to use Enterprise Integration Patterns including Message Router
and Pipes and Filters
◦ How to use various languages to express content-based
routing rules in Camel
• How to deal with Camel messages, headers, and attachments
You may choose to treat this as a hands-on tutorial, and work through
building the code and configuration files yourself. Each of the sections gives
detailed descriptions of the steps that need to be taken to get the
components and routes working in Camel, and takes you through tests to
make sure they are working as expected.
But each section also links to working copies of the source and
configuration files, so if you don't want the hands-on approach, you can
simply review and/or download the finished files.
High-Level Diagram
Here's more or less what the integration process looks like.
First, the input from the customers to Acme:
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And then, the output from Acme to the customers:
Tutorial Tasks
To get through this scenario, we're going to break it down into smaller pieces,
implement and test those, and then try to assemble the big scenario and test
that.
Here's what we'll try to accomplish:
1. Create a Maven build for the project
2. Get sample files for the customer Excel, CSV, and XML input
3. Get a sample file for the canonical XML format that Acme's
accounting system uses
4. Create an XSD for the canonical XML format
5. Create JAXB POJOs corresponding to the canonical XSD
6. Create an XSLT stylesheet to convert the Customer 1 (XML over FTP)
messages to the canonical format
7. Create a unit test to ensure that a simple Camel route invoking the
XSLT stylesheet works
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206
8. Create a POJO that converts a List> to the above
JAXB POJOs
◦ Note that Camel can automatically convert CSV input to a
List of Lists of Strings representing the rows and columns of
the CSV, so we'll use this POJO to handle Customer 2 (CSV
over HTTP)
9. Create a unit test to ensure that a simple Camel route invoking the
CSV processing works
10. Create a POJO that converts a Customer 3 Excel file to the above
JAXB POJOs (using POI to read Excel)
11. Create a unit test to ensure that a simple Camel route invoking the
Excel processing works
12. Create a POJO that reads an input message, takes an attachment off
the message, and replaces the body of the message with the
attachment
◦ This is assuming for Customer 3 (Excel over e-mail) that the
e-mail contains a single Excel file as an attachment, and the
actual e-mail body is throwaway
13. Build a set of Camel routes to handle the entire input (Customer ->
Acme) side of the scenario.
14. Build unit tests for the Camel input.
15. TODO: Tasks for the output (Acme -> Customer) side of the scenario
LET'S GET STARTED!
Step 1: Initial Maven build
We'll use Maven for this project as there will eventually be quite a few
dependencies and it's nice to have Maven handle them for us. You should
have a current version of Maven (e.g. 2.0.9) installed.
You can start with a pretty empty project directory and a Maven POM file,
or use a simple JAR archetype to create one.
Here's a sample POM. We've added a dependency on camel-core, and set
the compile version to 1.5 (so we can use annotations):
Listing 18. pom.xml
4.0.0org.apache.camel.tutorialbusiness-partners1.0-SNAPSHOTCamel Business Partners Tutorial
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camel-coreorg.apache.camel1.4.0org.apache.maven.pluginsmaven-compiler-plugin1.51.5
Step 2: Get Sample Files
You can make up your own if you like, but here are the "off the shelf" ones.
You can save yourself some time by downloading these to src/test/
resources in your Maven project.
• Customer 1 (XML): input-customer1.xml
• Customer 2 (CSV): input-customer2.csv
• Customer 3 (Excel): input-customer3.xls
• Canonical Acme XML Request: canonical-acme-request.xml
• Canonical Acme XML Response: TODO
If you look at these files, you'll see that the different input formats use
different field names and/or ordering, because of course the sales guys were
totally OK with that. Sigh.
Step 3: XSD and JAXB Beans for the Canonical XML Format
Here's the sample of the canonical XML file:
29/12/2008134A widget3
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10.456/5/2008218.82
If you're ambitions, you can write your own XSD (XML Schema) for files that
look like this, and save it to src/main/xsd.
Solution: If not, you can download mine, and save that to save it to src/
main/xsd.
Generating JAXB Beans
Down the road we'll want to deal with the XML as Java POJOs. We'll take a
moment now to set up those XML binding POJOs. So we'll update the Maven
POM to generate JAXB beans from the XSD file.
We need a dependency:
camel-jaxborg.apache.camel1.4.0
And a plugin configured:
org.codehaus.mojojaxb2-maven-pluginxjc
That should do it (it automatically looks for XML Schemas in src/main/xsd to
generate beans for). Run mvn install and it should emit the beans into
target/generated-sources/jaxb. Your IDE should see them there, though
you may need to update the project to reflect the new settings in the Maven
POM.
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Step 4: Initial Work on Customer 1 Input (XML over FTP)
To get a start on Customer 1, we'll create an XSLT template to convert the
Customer 1 sample file into the canonical XML format, write a small Camel
route to test it, and build that into a unit test. If we get through this, we can
be pretty sure that the XSLT template is valid and can be run safely in Camel.
Create an XSLT template
Start with the Customer 1 sample input. You want to create an XSLT template
to generate XML like the canonical XML sample above – an invoice element
with line-item elements (one per item in the original XML document). If
you're especially clever, you can populate the current date and order total
elements too.
Solution: My sample XSLT template isn't that smart, but it'll get you going
if you don't want to write one of your own.
Create a unit test
Here's where we get to some meaty Camel work. We need to:
• Set up a unit test
• That loads a Camel configuration
• That has a route invoking our XSLT
• Where the test sends a message to the route
• And ensures that some XML comes out the end of the route
The easiest way to do this is to set up a Spring context that defines the
Camel stuff, and then use a base unit test class from Spring that knows how
to load a Spring context to run tests against. So, the procedure is:
Set Up a Skeletal Camel/Spring Unit Test
1. Add dependencies on Camel-Spring, and the Spring test JAR (which
will automatically bring in JUnit 3.8.x) to your POM:
camel-springorg.apache.camel1.4.0spring-testorg.springframework2.5.5
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test
2. Create a new unit test class in src/test/java/your-package-here,
perhaps called XMLInputTest.java
3. Make the test extend Spring's AbstractJUnit38SpringContextTests
class, so it can load a Spring context for the test
4. Create a Spring context configuration file in src/test/resources,
perhaps called XMLInputTest-context.xml
5. In the unit test class, use the class-level @ContextConfiguration
annotation to indicate that a Spring context should be loaded
◦ By default, this looks for a Context configuration file called
TestClassName-context.xml in a subdirectory
corresponding to the package of the test class. For instance,
if your test class was
org.apache.camel.tutorial.XMLInputTest, it would look
for org/apache/camel/tutorial/XMLInputTestcontext.xml
◦ To override this default, use the locations attribute on the
@ContextConfiguration annotation to provide specific context
file locations (starting each path with a / if you don't want it
to be relative to the package directory). My solution does this
so I can put the context file directly in src/test/resources
instead of in a package directory under there.
6. Add a CamelContext instance variable to the test class, with the
@Autowired annotation. That way Spring will automatically pull the
CamelContext out of the Spring context and inject it into our test
class.
7. Add a ProducerTemplate instance variable and a setUp method that
instantiates it from the CamelContext. We'll use the
ProducerTemplate later to send messages to the route.
protected ProducerTemplate template;
protected void setUp() throws Exception {
super.setUp();
template = camelContext.createProducerTemplate();
}
8. Put in an empty test method just for the moment (so when we run
this we can see that "1 test succeeded")
9. Add the Spring element (including the Camel Namespace)
with an empty element to the Spring context, like
this:
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Test it by running mvn install and make sure there are no build errors. So far
it doesn't test much; just that your project and test and source files are all
organized correctly, and the one empty test method completes successfully.
Solution: Your test class might look something like this:
• src/test/java/org/apache/camel/tutorial/XMLInputTest.java
• src/test/resources/XMLInputTest-context.xml (same as just above)
Flesh Out the Unit Test
So now
sample
out:
1.
2.
we're going to write a Camel route that applies the XSLT to the
Customer 1 input file, and makes sure that some XML output comes
Save the input-customer1.xml file to src/test/resources
Save your XSLT file (created in the previous step) to src/main/
resources
3. Write a Camel Route, either right in the Spring XML, or using the Java
DSL (in another class under src/test/java somewhere). This route
should use the Pipes and Filters integration pattern to:
1. Start from the endpoint direct:start (which lets the test
conveniently pass messages into the route)
2. Call the endpoint xslt:YourXSLTFile.xsl (to transform the
message with the specified XSLT template)
3. Send the result to the endpoint mock:finish (which lets the
test verify the route output)
4. Add a test method to the unit test class that:
1. Get a reference to the Mock endpoint mock:finish using
code like this:
MockEndpoint finish = MockEndpoint.resolve(camelContext,
"mock:finish");
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2. Set the expectedMessageCount on that endpoint to 1
3. Get a reference to the Customer 1 input file, using code like
this:
InputStream in =
XMLInputTest.class.getResourceAsStream("/input-partner1.xml");
assertNotNull(in);
4. Send that InputStream as a message to the direct:start
endpoint, using code like this:
template.sendBody("direct:start", in);
Note that we can send the sample file body in several
formats (File, InputStream, String, etc.) but in this case an
InputStream is pretty convenient.
5. Ensure that the message made it through the route to the
final endpoint, by testing all configured Mock endpoints like
this:
MockEndpoint.assertIsSatisfied(camelContext);
6. If you like, inspect the final message body using some code
like finish.getExchanges().get(0).getIn().getBody().
▪ If you do this, you'll need to know what format that
body is – String, byte array, InputStream, etc.
5. Run your test with mvn install and make sure the build completes
successfully.
Solution: Your finished test might look something like this:
• src/test/java/org/apache/camel/tutorial/XMLInputTest.java
• For XML Configuration:
◦ src/test/resources/XMLInputTest-context.xml
• Or, for Java DSL Configuration:
◦ src/test/resources/XMLInputTest-dsl-context.xml
◦ src/test/java/org/apache/camel/tutorial/
routes/XMLInputTestRoute.java
Step 5: Initial Work on Customer 2 Input (CSV over HTTP)
To get a start on Customer 2, we'll create a POJO to convert the Customer 2
sample CSV data into the JAXB POJOs representing the canonical XML format,
write a small Camel route to test it, and build that into a unit test. If we get
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Test Base Class
Once your test class is working, you might want to extract things
like the @Autowired CamelContext, the ProducerTemplate, and the
setUp method to a custom base class that you extend with your
other tests.
through this, we can be pretty sure that the CSV conversion and JAXB
handling is valid and can be run safely in Camel.
Create a CSV-handling POJO
To begin with, CSV is a known data format in Camel. Camel can convert a
CSV file to a List (representing rows in the CSV) of Lists (representing cells in
the row) of Strings (the data for each cell). That means our POJO can just
assume the data coming in is of type List>, and we can
declare a method with that as the argument.
Looking at the JAXB code in target/generated-sources/jaxb, it looks
like an Invoice object represents the whole document, with a nested list of
LineItemType objects for the line items. Therefore our POJO method will
return an Invoice (a document in the canonical XML format).
So to implement the CSV-to-JAXB POJO, we need to do something like this:
1. Create a new class under src/main/java, perhaps called
CSVConverterBean.
2. Add a method, with one argument of type List> and
the return type Invoice
◦ You may annotate the argument with @Body to specifically
designate it as the body of the incoming message
3. In the method, the logic should look roughly like this:
1. Create a new Invoice, using the method on the generated
ObjectFactory class
2. Loop through all the rows in the incoming CSV (the outer
List)
3. Skip the first row, which contains headers (column names)
4. For the other rows:
1. Create a new LineItemType (using the
ObjectFactory again)
2. Pick out all the cell values (the Strings in the inner
List) and put them into the correct fields of the
LineItemType
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214
▪ Not all of the values will actually go into the
line item in this example
▪ You may hardcode the column ordering based
on the sample data file, or else try to read it
dynamically from the headers in the first line
▪ Note that you'll need to use a JAXB
DatatypeFactory to create the
XMLGregorianCalendar values that JAXB
uses for the date fields in the XML – which
probably means using a SimpleDateFormat
to parse the date and setting that date on a
GregorianCalendar
3. Add the line item to the invoice
5. Populate the partner ID, date of receipt, and order total on
the Invoice
6. Throw any exceptions out of the method, so Camel knows
something went wrong
7. Return the finished Invoice
Solution: Here's an example of what the CSVConverterBean might look like.
Create a unit test
Start with a simple test class and test Spring context like last time, perhaps
based on the name CSVInputTest:
Listing 19. CSVInputTest.java
/**
* A test class the ensure we can convert Partner 2 CSV input files to the
* canonical XML output format, using JAXB POJOs.
*/
@ContextConfiguration(locations = "/CSVInputTest-context.xml")
public class CSVInputTest extends AbstractJUnit38SpringContextTests {
@Autowired
protected CamelContext camelContext;
protected ProducerTemplate template;
protected void setUp() throws Exception {
super.setUp();
template = camelContext.createProducerTemplate();
}
public void testCSVConversion() {
// TODO
}
}
Listing 20. CSVInputTest-context.xml
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Now the meaty part is to flesh out the test class and write the Camel routes.
1. Update the Maven POM to include CSV Data Format support:
camel-csvorg.apache.camel1.4.0
2. Write the routes (right in the Spring XML context, or using the Java
DSL) for the CSV conversion process, again using the Pipes and
Filters pattern:
1. Start from the endpoint direct:CSVstart (which lets the test
conveniently pass messages into the route). We'll name this
differently than the starting point for the previous test, in
case you use the Java DSL and put all your routes in the
same package (which would mean that each test would load
the DSL routes for several tests.)
2. This time, there's a little preparation to be done. Camel
doesn't know that the initial input is a CSV, so it won't be
able to convert it to the expected List>
without a little hint. For that, we need an unmarshal
transformation in the route. The unmarshal method (in the
DSL) or element (in the XML) takes a child indicating the
format to unmarshal; in this case that should be csv.
3. Next invoke the POJO to transform the message with a
bean:CSVConverter endpoint
4. As before, send the result to the endpoint mock:finish (which
lets the test verify the route output)
5. Finally, we need a Spring element in the Spring
context XML file (but outside the element)
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216
to define the Spring bean that our route invokes. This Spring
bean should have a name attribute that matches the name
used in the bean endpoint (CSVConverter in the example
above), and a class attribute that points to the CSV-to-JAXB
POJO class you wrote above (such as,
org.apache.camel.tutorial.CSVConverterBean). When
Spring is in the picture, any bean endpoints look up Spring
beans with the specified name.
3. Write a test method in the test class, which should look very similar
to the previous test class:
1. Get the MockEndpoint for the final endpoint, and tell it to
expect one message
2. Load the Partner 2 sample CSV file from the ClassPath, and
send it as the body of a message to the starting endpoint
3. Verify that the final MockEndpoint is satisfied (that is, it
received one message) and examine the message body if
you like
▪ Note that we didn't marshal the JAXB POJOs to XML in
this test, so the final message should contain an
Invoice as the body. You could write a simple line of
code to get the Exchange (and Message) from the
MockEndpoint to confirm that.
4. Run this new test with mvn install and make sure it passes and the
build completes successfully.
Solution: Your finished test might look something like this:
• src/test/java/org/apache/camel/tutorial/CSVInputTest.java
• For XML Configuration:
◦ src/test/resources/CSVInputTest-context.xml
• Or, for Java DSL Configuration:
◦ src/test/resources/CSVInputTest-dsl-context.xml
◦ src/test/java/org/apache/camel/tutorial/
routes/CSVInputTestRoute.java
Step 6: Initial Work on Customer 3 Input (Excel over e-mail)
To get a start on Customer 3, we'll create a POJO to convert the Customer 3
sample Excel data into the JAXB POJOs representing the canonical XML
format, write a small Camel route to test it, and build that into a unit test. If
we get through this, we can be pretty sure that the Excel conversion and
JAXB handling is valid and can be run safely in Camel.
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T U T O R IAL S
Create an Excel-handling POJO
Camel does not have a data format handler for Excel by default. We have two
options – create an Excel DataFormat (so Camel can convert Excel
spreadsheets to something like the CSV List> automatically),
or create a POJO that can translate Excel data manually. For now, the second
approach is easier (if we go the DataFormat route, we need code to both
read and write Excel files, whereas otherwise read-only will do).
So, we need a POJO with a method that takes something like an
InputStream or byte[] as an argument, and returns in Invoice as before.
The process should look something like this:
1. Update the Maven POM to include POI support:
poiorg.apache.poi3.1-FINAL
2. Create a new class under src/main/java, perhaps called
ExcelConverterBean.
3. Add a method, with one argument of type InputStream and the
return type Invoice
◦ You may annotate the argument with @Body to specifically
designate it as the body of the incoming message
4. In the method, the logic should look roughly like this:
1. Create a new Invoice, using the method on the generated
ObjectFactory class
2. Create a new HSSFWorkbook from the InputStream, and get
the first sheet from it
3. Loop through all the rows in the sheet
4. Skip the first row, which contains headers (column names)
5. For the other rows:
1. Create a new LineItemType (using the
ObjectFactory again)
2. Pick out all the cell values and put them into the
correct fields of the LineItemType (you'll need some
data type conversion logic)
▪ Not all of the values will actually go into the
line item in this example
▪ You may hardcode the column ordering based
on the sample data file, or else try to read it
dynamically from the headers in the first line
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218
▪ Note that you'll need to use a JAXB
DatatypeFactory to create the
XMLGregorianCalendar values that JAXB
uses for the date fields in the XML – which
probably means setting the date from a date
cell on a GregorianCalendar
3. Add the line item to the invoice
6. Populate the partner ID, date of receipt, and order total on
the Invoice
7. Throw any exceptions out of the method, so Camel knows
something went wrong
8. Return the finished Invoice
Solution: Here's an example of what the ExcelConverterBean might look
like.
Create a unit test
The unit tests should be pretty familiar now. The test class and context for
the Excel bean should be quite similar to the CSV bean.
1. Create the basic test class and corresponding Spring Context XML
configuration file
2. The XML config should look a lot like the CSV test, except:
◦ Remember to use a different start endpoint name if you're
using the Java DSL and not use separate packages per test
◦ You don't need the unmarshal step since the Excel POJO
takes the raw InputStream from the source endpoint
◦ You'll declare a and endpoint for the Excel bean
prepared above instead of the CSV bean
3. The test class should look a lot like the CSV test, except use the right
input file name and start endpoint name.
Solution: Your finished test might look something like this:
• src/test/java/org/apache/camel/tutorial/ExcelInputTest.java
• For XML Configuration:
◦ src/test/resources/ExcelInputTest-context.xml
• Or, for Java DSL Configuration:
◦ src/test/resources/ExcelInputTest-dsl-context.xml
◦ src/test/java/org/apache/camel/tutorial/
routes/ExcelInputTestRoute.java
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T U T O R IAL S
Logging
You may notice that your tests emit a lot less output all of a sudden.
The dependency on POI brought in Log4J and configured commonslogging to use it, so now we need a log4j.properties file to configure
log output. You can use the attached one (snarfed from ActiveMQ)
or write your own; either way save it to src/main/resources to
ensure you continue to see log output.
Step 7: Put this all together into Camel routes for the Customer
Input
With all the data type conversions working, the next step is to write the real
routes that listen for HTTP, FTP, or e-mail input, and write the final XML
output to an ActiveMQ queue. Along the way these routes will use the data
conversions we've developed above.
So we'll create 3 routes to start with, as shown in the diagram back at the
beginning:
1. Accept XML orders over FTP from Customer 1 (we'll assume the FTP
server dumps files in a local directory on the Camel machine)
2. Accept CSV orders over HTTP from Customer 2
3. Accept Excel orders via e-mail from Customer 3 (we'll assume the
messages are sent to an account we can access via IMAP)
...
Step 8: Create a unit test for the Customer Input Routes
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Languages Supported
Appendix
To support flexible and powerful Enterprise Integration Patterns Camel
supports various Languages to create an Expression or Predicate within
either the Routing Domain Specific Language or the Xml Configuration. The
following languages are supported
BEAN LANGUAGE
The purpose of the Bean Language is to be able to implement an Expression
or Predicate using a simple method on a bean.
So the idea is you specify a bean name which will then be resolved in the
Registry such as the Spring ApplicationContext then a method is invoked to
evaluate the Expression or Predicate.
If no method name is provided then one is attempted to be chosen using
the rules for Bean Binding; using the type of the message body and using
any annotations on the bean methods.
The Bean Binding rules are used to bind the Message Exchange to the
method parameters; so you can annotate the bean to extract headers or
other expressions such as XPath or XQuery from the message.
Using Bean Expressions from the Java DSL
from("activemq:topic:OrdersTopic").
filter().method("myBean", "isGoldCustomer").
to("activemq:BigSpendersQueue");
Using Bean Expressions from XML
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Writing the expression bean
The bean in the above examples is just any old Java Bean with a method
called isGoldCustomer() that returns some object that is easily converted to a
boolean value in this case, as its used as a predicate.
So we could implement it like this...
public class MyBean {
public boolean isGoldCustomer(Exchange exchange) {
...
}
}
We can also use the Bean Integration annotations. For example you could
do...
public boolean isGoldCustomer(String body) {...}
or
public boolean isGoldCustomer(@Header(name = "foo") Integer fooHeader) {...}
So you can bind parameters of the method to the Exchange, the Message or
individual headers, properties, the body or other expressions.
Non registry beans
As of Camel 1.5 the Bean Language also supports invoking beans that isn't
registered in the Registry. This is usable for quickly to invoke a bean from
Java DSL where you don't need to register the bean in the Registry such as
the Spring ApplicationContext.
Camel can instantiate the bean and invoke the method if given a class or
invoke an already existing instance. This is illustrated from the example
below:
NOTE This bean DSL is supported since Camel 2.0-M2
from("activemq:topic:OrdersTopic").
filter().expression(BeanLanguage(MyBean.class, "isGoldCustomer")).
to("activemq:BigSpendersQueue");
The 2nd parameter isGoldCustomer is an optional parameter to explicit set
the method name to invoke. If not provided Camel will try to invoke the best
suited method. If case of ambiguity Camel will thrown an Exception. In these
situations the 2nd parameter can solve this problem. Also the code is more
L AN G UA GE S S U PP O RTE D A PPE NDIX
222
readable if the method name is provided. The 1st parameter can also be an
existing instance of a Bean such as:
private MyBean my;
from("activemq:topic:OrdersTopic").
filter().expression(BeanLanguage.bean(my, "isGoldCustomer")).
to("activemq:BigSpendersQueue");
In Camel 2.2 onwards you can avoid the BeanLanguage and have it just as:
private MyBean my;
from("activemq:topic:OrdersTopic").
filter().expression(bean(my, "isGoldCustomer")).
to("activemq:BigSpendersQueue");
Which also can be done in a bit shorter and nice way:
private MyBean my;
from("activemq:topic:OrdersTopic").
filter().method(my, "isGoldCustomer").
to("activemq:BigSpendersQueue");
Other examples
We have some test cases you can look at if it'll help
• MethodFilterTest is a JUnit test case showing the Java DSL use of the
bean expression being used in a filter
• aggregator.xml is a Spring XML test case for the Aggregator which
uses a bean method call to test for the completion of the
aggregation.
Dependencies
The Bean language is part of camel-core.
CONSTANT EXPRESSION LANGUAGE
The Constant Expression Language is really just a way to specify constant
strings as a type of expression.
Available as of Camel 1.5
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Example usage
The setHeader element of the Spring DSL can utilize a constant expression
like:
the value
in this case, the Message coming from the seda:a Endpoint will have
'theHeader' header set to the constant value 'the value'.
And the same example using Java DSL:
from("seda:a").setHeader("theHeader", constant("the value")).to("mock:b");
Dependencies
The Constant language is part of camel-core.
EL
Camel supports the unified JSP and JSF Expression Language via the JUEL to
allow an Expression or Predicate to be used in the DSL or Xml Configuration.
For example you could use EL inside a Message Filter in XML
${in.headers.foo == 'bar'}
You could also use slightly different syntax, e.g. if the header name is not a
valid identifier:
${in.headers['My Header'] == 'bar'}
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You could use EL to create an Predicate in a Message Filter or as an
Expression for a Recipient List
Variables
Variable
Type
Description
exchange
Exchange
the Exchange object
in
Message
the exchange.in message
out
Message
the exchange.out message
Samples
You can use EL dot notation to invoke operations. If you for instance have a
body that contains a POJO that has a getFamiliyName method then you can
construct the syntax as follows:
"$in.body.familyName"
Dependencies
To use EL in your camel routes you need to add the a dependency on cameljuel which implements the EL language.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-juel1.6.1
Otherwise you'll also need to include JUEL.
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HEADER EXPRESSION LANGUAGE
The Header Expression Language allows you to extract values of named
headers.
Available as of Camel 1.5
Example usage
The recipientList element of the Spring DSL can utilize a header expression
like:
myHeader
In this case, the list of recipients are contained in the header 'myHeader'.
And the same example in Java DSL:
from("direct:a").recipientList(header("myHeader"));
And with a slightly different syntax where you use the builder to the fullest
(i.e. avoid using parameters but using stacked operations, notice that header
is not a parameter but a stacked method call)
from("direct:a").recipientList().header("myHeader");
Dependencies
The Header language is part of camel-core.
JXPATH
Camel supports JXPath to allow XPath expressions to be used on beans in an
Expression or Predicate to be used in the DSL or Xml Configuration. For
example you could use JXPath to create an Predicate in a Message Filter or as
an Expression for a Recipient List.
From 1.3 of Camel onwards you can use XPath expressions directly using
smart completion in your IDE as follows
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from("queue:foo").filter().
jxpath("/in/body/foo").
to("queue:bar")
Variables
Variable
Type
Description
this
Exchange
the Exchange object
in
Message
the exchange.in message
out
Message
the exchange.out message
Using XML configuration
If you prefer to configure your routes in your Spring XML file then you can
use JXPath expressions as follows
in/body/name = 'James'
Examples
Here is a simple example using a JXPath expression as a predicate in a
Message Filter
from("direct:start").
filter().jxpath("in/body/name='James'").
to("mock:result");
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L A N G UA G E S S U P P ORT E D A P P E N D I X
JXPATH INJECTION
You can use Bean Integration to invoke a method on a bean and use various
languages such as JXPath to extract a value from the message and bind it to
a method parameter.
For example
public class Foo {
@MessageDriven(uri = "activemq:my.queue")
public void doSomething(@JXPath("in/body/foo") String correlationID, @Body String
body) {
// process the inbound message here
}
}
Dependencies
To use JXpath in your camel routes you need to add the a dependency on
camel-jxpath which implements the JXpath language.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-jxpath1.4.0
Otherwise, you'll also need Commons JXPath.
MVEL
Avialable in Camel 2.0
Camel allows Mvel to be used as an Expression or Predicate the DSL or
Xml Configuration.
You could use Mvel to create an Predicate in a Message Filter or as an
Expression for a Recipient List
You can use Mvel dot notation to invoke operations. If you for instance
have a body that contains a POJO that has a getFamiliyName method then
you can construct the syntax as follows:
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"request.body.familyName"
// or
"getRequest().getBody().getFamilyName()"
Variables
Variable
Type
Description
this
Exchange
the Exchange is the root object
exchange
Exchange
the Exchange object
exception
Throwable
the Exchange exception (if any)
exchangeId
String
the exchange id
fault
Message
the Fault message (if any)
request
Message
the exchange.in message
response
Message
the exchange.out message (if any)
properties
Map
the exchange properties
property(name)
Object
the property by the given name
property(name,
type)
Type
the property by the given name as the
given type
Samples
For example you could use Mvel inside a Message Filter in XML
request.headers.foo == 'bar'
And the sample using Java DSL:
from("seda:foo").filter().mvel("request.headers.foo == 'bar'").to("seda:bar");
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L A N G UA G E S S U P P ORT E D A P P E N D I X
Dependencies
To use Mvel in your camel routes you need to add the a dependency on
camel-mvel which implements the Mvel language.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-mvel2.0.0
Otherwise, you'll also need MVEL
OGNL
Camel allows OGNL to be used as an Expression or Predicate the DSL or Xml
Configuration.
You could use OGNL to create an Predicate in a Message Filter or as an
Expression for a Recipient List
You can use OGNL dot notation to invoke operations. If you for instance
have a body that contains a POJO that has a getFamiliyName method then
you can construct the syntax as follows:
"request.body.familyName"
// or
"getRequest().getBody().getFamilyName()"
Variables
Variable
Type
Description
this
Exchange
the Exchange is the root object
exchange
Exchange
the Exchange object
exception
Throwable
the Exchange exception (if any)
exchangeId
String
the exchange id
fault
Message
the Fault message (if any)
request
Message
the exchange.in message
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response
Message
the exchange.out message (if any)
properties
Map
the exchange properties
property(name)
Object
the property by the given name
property(name,
type)
Type
the property by the given name as the
given type
Samples
For example you could use OGNL inside a Message Filter in XML
request.headers.foo == 'bar'
And the sample using Java DSL:
from("seda:foo").filter().ognl("request.headers.foo == 'bar'").to("seda:bar");
Dependencies
To use OGNL in your camel routes you need to add the a dependency on
camel-ognl which implements the OGNL language.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-ognl1.4.0
Otherwise, you'll also need OGNL
PROPERTY EXPRESSION LANGUAGE
The Property Expression Language allows you to extract values of named
exchange properties.
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L A N G UA G E S S U P P ORT E D A P P E N D I X
Available as of Camel 2.0
Example usage
The recipientList element of the Spring DSL can utilize a property expression
like:
myProperty
In this case, the list of recipients are contained in the property 'myProperty'.
And the same example in Java DSL:
from("direct:a").recipientList(property("myProperty"));
And with a slightly different syntax where you use the builder to the fullest
(i.e. avoid using parameters but using stacked operations, notice that
property is not a parameter but a stacked method call)
from("direct:a").recipientList().property("myProperty");
Dependencies
The Property language is part of camel-core.
SCRIPTING LANGUAGES
Camel supports a number of scripting languages which can be used to create
an Expression or Predicate via the standard JSR 223 which is a standard part
of Java 6.
The following scripting languages are integrated into the DSL:
Language
DSL keyword
EL
el
Groovy
groovy
JavaScript
javaScript
JoSQL
sql
L AN G UA GE S S U PP O RTE D A PPE NDIX
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JXPath
jxpath
MVEL
mvel
OGNL
ognl
PHP
php
Python
python
Ruby
ruby
XPath
xpath
XQuery
xquery
However any JSR 223 scripting language can be used using the generic DSL
methods.
ScriptContext
The JSR-223 scripting languages ScriptContext is pre configured with the
following attributes all set at ENGINE_SCOPE:
233
Attribute
Type
Value
context
org.apache.camel.CamelContext
The Camel
Context
exchange
org.apache.camel.Exchange
The
current
Exchange
request
org.apache.camel.Message
The IN
message
response
org.apache.camel.Message
The OUT
message
L A N G UA G E S S U P P ORT E D A P P E N D I X
properties
org.apache.camel.builder.script.PropertiesFunction
Camel
2.9:
Function
with a
resolve
method to
make it
easier to
use
Camels
Properties
component
from
scripts.
See further
below for
example.
Attributes
You can add your own attributes with the attribute(name, value) DSL
method, such as:
In the sample below we add an attribute user that is an object we already
have instantiated as myUser. This object has a getFirstName() method that
we want to set as header on the message. We use the groovy language to
concat the first and last name into a single string that is returned.
from("direct:in").setHeader("name").groovy("'$user.firstName
$user.lastName'").attribute("user", myUser).to("seda:users");
Any scripting language
Camel can run any JSR-223 scripting languages using the script DSL
method such as:
from("direct:in").setHeader("firstName").script("jaskel",
"user.firstName").attribute("user", myUser).to("seda:users");
This is a bit different using the Spring DSL where you use the expression
element that doesn't support setting attributes (yet):
L AN G UA GE S S U PP O RTE D A PPE NDIX
234
user.firstName
You can also use predicates e.g. in a Filter:
request.getHeaders().get("Foo").equals("Bar")
See Scripting Languages for the list of languages with explicit DSL support.
Some languages without specific DSL support but known to work with
these generic methods include:
Language
Implementation
language="..." value
BeanShell
BeanShell 2.0b5
beanshell or bsh
Additional arguments to ScriptingEngine
Available as of Camel 2.8
You can provide additional arguments to the ScriptingEngine using a
header on the Camel message with the key CamelScriptArguments.
See this example:
public void testArgumentsExample() throws Exception {
if (!ScriptTestHelper.canRunTestOnThisPlatform()) {
return;
}
getMockEndpoint("mock:result").expectedMessageCount(0);
getMockEndpoint("mock:unmatched").expectedMessageCount(1);
// additional arguments to ScriptEngine
Map arguments = new HashMap();
arguments.put("foo", "bar");
arguments.put("baz", 7);
// those additional arguments is provided as a header on the Camel Message
template.sendBodyAndHeader("direct:start", "hello", ScriptBuilder.ARGUMENTS,
arguments);
assertMockEndpointsSatisfied();
}
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L A N G UA G E S S U P P ORT E D A P P E N D I X
Using properties function
Available as of Camel 2.9
If you need to use the Properties component from a script to lookup
property placeholders, then its a bit cumbersome to do so.
For example to set a header name myHeader with a value from a property
placeholder, which key is provided in a header named "foo".
.setHeader("myHeader").groovy("context.resolvePropertyPlaceholders('{{' +
request.headers.get('foo') + '}}')")
From Camel 2.9 onwards you can now use the properties function and the
same example is simpler:
.setHeader("myHeader").groovy("properties.resolve(request.headers.get('foo'))")
Dependencies
To use scripting languages in your camel routes you need to add the a
dependency on camel-script which integrates the JSR-223 scripting engine.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-scriptx.x.x
SEE ALSO
• Languages
• DSL
• Xml Configuration
BEANSHELL
Camel supports BeanShell among other Scripting Languages to allow an
Expression or Predicate to be used in the DSL or Xml Configuration.
To use a BeanShell expression use the following Java code:
L AN G UA GE S S U PP O RTE D A PPE NDIX
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...choice()
.when(script("beanshell", "request.getHeaders().get(\"foo\").equals(\"bar\")"))
.to("...")
Or the something like this in your Spring XML:
request.getHeaders().get("Foo") == null
...
You could follow the examples above to create an Predicate in a Message
Filter or as an Expression for a Recipient List
ScriptContext
The JSR-223 scripting languages ScriptContext is pre configured with the
following attributes all set at ENGINE_SCOPE:
237
Attribute
Type
Value
context
org.apache.camel.CamelContext
The Camel
Context
exchange
org.apache.camel.Exchange
The
current
Exchange
request
org.apache.camel.Message
The IN
message
response
org.apache.camel.Message
The OUT
message
L A N G UA G E S S U P P ORT E D A P P E N D I X
BeanShell Issues
You must use BeanShell 2.0b5 or greater. Note that as of 2.0b5
BeanShell cannot compile scripts, which causes Camel releases
before 2.6 to fail when configured with BeanShell expressions.
properties
org.apache.camel.builder.script.PropertiesFunction
Camel
2.9:
Function
with a
resolve
method to
make it
easier to
use
Camels
Properties
component
from
scripts.
See further
below for
example.
Attributes
You can add your own attributes with the attribute(name, value) DSL
method, such as:
In the sample below we add an attribute user that is an object we already
have instantiated as myUser. This object has a getFirstName() method that
we want to set as header on the message. We use the groovy language to
concat the first and last name into a single string that is returned.
from("direct:in").setHeader("name").groovy("'$user.firstName
$user.lastName'").attribute("user", myUser).to("seda:users");
Any scripting language
Camel can run any JSR-223 scripting languages using the script DSL
method such as:
L AN G UA GE S S U PP O RTE D A PPE NDIX
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from("direct:in").setHeader("firstName").script("jaskel",
"user.firstName").attribute("user", myUser).to("seda:users");
This is a bit different using the Spring DSL where you use the expression
element that doesn't support setting attributes (yet):
user.firstName
You can also use predicates e.g. in a Filter:
request.getHeaders().get("Foo").equals("Bar")
See Scripting Languages for the list of languages with explicit DSL support.
Some languages without specific DSL support but known to work with
these generic methods include:
Language
Implementation
language="..." value
BeanShell
BeanShell 2.0b5
beanshell or bsh
Additional arguments to ScriptingEngine
Available as of Camel 2.8
You can provide additional arguments to the ScriptingEngine using a
header on the Camel message with the key CamelScriptArguments.
See this example:
public void testArgumentsExample() throws Exception {
if (!ScriptTestHelper.canRunTestOnThisPlatform()) {
return;
}
getMockEndpoint("mock:result").expectedMessageCount(0);
getMockEndpoint("mock:unmatched").expectedMessageCount(1);
// additional arguments to ScriptEngine
Map arguments = new HashMap();
arguments.put("foo", "bar");
arguments.put("baz", 7);
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L A N G UA G E S S U P P ORT E D A P P E N D I X
// those additional arguments is provided as a header on the Camel Message
template.sendBodyAndHeader("direct:start", "hello", ScriptBuilder.ARGUMENTS,
arguments);
assertMockEndpointsSatisfied();
}
Using properties function
Available as of Camel 2.9
If you need to use the Properties component from a script to lookup
property placeholders, then its a bit cumbersome to do so.
For example to set a header name myHeader with a value from a property
placeholder, which key is provided in a header named "foo".
.setHeader("myHeader").groovy("context.resolvePropertyPlaceholders('{{' +
request.headers.get('foo') + '}}')")
From Camel 2.9 onwards you can now use the properties function and the
same example is simpler:
.setHeader("myHeader").groovy("properties.resolve(request.headers.get('foo'))")
Dependencies
To use scripting languages in your camel routes you need to add the a
dependency on camel-script which integrates the JSR-223 scripting engine.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-scriptx.x.x
JAVASCRIPT
Camel supports JavaScript/ECMAScript among other Scripting Languages to
allow an Expression or Predicate to be used in the DSL or Xml Configuration.
L AN G UA GE S S U PP O RTE D A PPE NDIX
240
To use a JavaScript expression use the following Java code
... javaScript("someJavaScriptExpression") ...
For example you could use the javaScript function to create an Predicate in
a Message Filter or as an Expression for a Recipient List
Example
In the sample below we use JavaScript to create a Predicate use in the route
path, to route exchanges from admin users to a special queue.
from("direct:start")
.choice()
.when().javaScript("request.headers.get('user') ==
'admin'").to("seda:adminQueue")
.otherwise()
.to("seda:regularQueue");
And a Spring DSL sample as well:
request.headers.get('user') == 'admin'
ScriptContext
The JSR-223 scripting languages ScriptContext is pre configured with the
following attributes all set at ENGINE_SCOPE:
241
Attribute
Type
Value
context
org.apache.camel.CamelContext
The Camel
Context
exchange
org.apache.camel.Exchange
The
current
Exchange
L A N G UA G E S S U P P ORT E D A P P E N D I X
request
org.apache.camel.Message
The IN
message
response
org.apache.camel.Message
The OUT
message
org.apache.camel.builder.script.PropertiesFunction
Camel
2.9:
Function
with a
resolve
method to
make it
easier to
use
Camels
Properties
component
from
scripts.
See further
below for
example.
properties
Attributes
You can add your own attributes with the attribute(name, value) DSL
method, such as:
In the sample below we add an attribute user that is an object we already
have instantiated as myUser. This object has a getFirstName() method that
we want to set as header on the message. We use the groovy language to
concat the first and last name into a single string that is returned.
from("direct:in").setHeader("name").groovy("'$user.firstName
$user.lastName'").attribute("user", myUser).to("seda:users");
Any scripting language
Camel can run any JSR-223 scripting languages using the script DSL
method such as:
L AN G UA GE S S U PP O RTE D A PPE NDIX
242
from("direct:in").setHeader("firstName").script("jaskel",
"user.firstName").attribute("user", myUser).to("seda:users");
This is a bit different using the Spring DSL where you use the expression
element that doesn't support setting attributes (yet):
user.firstName
You can also use predicates e.g. in a Filter:
request.getHeaders().get("Foo").equals("Bar")
See Scripting Languages for the list of languages with explicit DSL support.
Some languages without specific DSL support but known to work with
these generic methods include:
Language
Implementation
language="..." value
BeanShell
BeanShell 2.0b5
beanshell or bsh
Additional arguments to ScriptingEngine
Available as of Camel 2.8
You can provide additional arguments to the ScriptingEngine using a
header on the Camel message with the key CamelScriptArguments.
See this example:
public void testArgumentsExample() throws Exception {
if (!ScriptTestHelper.canRunTestOnThisPlatform()) {
return;
}
getMockEndpoint("mock:result").expectedMessageCount(0);
getMockEndpoint("mock:unmatched").expectedMessageCount(1);
// additional arguments to ScriptEngine
Map arguments = new HashMap();
arguments.put("foo", "bar");
arguments.put("baz", 7);
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L A N G UA G E S S U P P ORT E D A P P E N D I X
// those additional arguments is provided as a header on the Camel Message
template.sendBodyAndHeader("direct:start", "hello", ScriptBuilder.ARGUMENTS,
arguments);
assertMockEndpointsSatisfied();
}
Using properties function
Available as of Camel 2.9
If you need to use the Properties component from a script to lookup
property placeholders, then its a bit cumbersome to do so.
For example to set a header name myHeader with a value from a property
placeholder, which key is provided in a header named "foo".
.setHeader("myHeader").groovy("context.resolvePropertyPlaceholders('{{' +
request.headers.get('foo') + '}}')")
From Camel 2.9 onwards you can now use the properties function and the
same example is simpler:
.setHeader("myHeader").groovy("properties.resolve(request.headers.get('foo'))")
Dependencies
To use scripting languages in your camel routes you need to add the a
dependency on camel-script which integrates the JSR-223 scripting engine.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-scriptx.x.x
GROOVY
Camel supports Groovy among other Scripting Languages to allow an
Expression or Predicate to be used in the DSL or Xml Configuration.
L AN G UA GE S S U PP O RTE D A PPE NDIX
244
To use a Groovy expression use the following Java code
... groovy("someGroovyExpression") ...
For example you could use the groovy function to create an Predicate in a
Message Filter or as an Expression for a Recipient List
Example
// lets route if a line item is over $100
from("queue:foo").filter(groovy("request.lineItems.any { i -> i.value > 100
}")).to("queue:bar")
And the Spring DSL:
request.lineItems.any { i -> i.value > 100 }
ScriptContext
The JSR-223 scripting languages ScriptContext is pre configured with the
following attributes all set at ENGINE_SCOPE:
245
Attribute
Type
Value
context
org.apache.camel.CamelContext
The Camel
Context
exchange
org.apache.camel.Exchange
The
current
Exchange
request
org.apache.camel.Message
The IN
message
response
org.apache.camel.Message
The OUT
message
L A N G UA G E S S U P P ORT E D A P P E N D I X
properties
org.apache.camel.builder.script.PropertiesFunction
Camel
2.9:
Function
with a
resolve
method to
make it
easier to
use
Camels
Properties
component
from
scripts.
See further
below for
example.
Attributes
You can add your own attributes with the attribute(name, value) DSL
method, such as:
In the sample below we add an attribute user that is an object we already
have instantiated as myUser. This object has a getFirstName() method that
we want to set as header on the message. We use the groovy language to
concat the first and last name into a single string that is returned.
from("direct:in").setHeader("name").groovy("'$user.firstName
$user.lastName'").attribute("user", myUser).to("seda:users");
Any scripting language
Camel can run any JSR-223 scripting languages using the script DSL
method such as:
from("direct:in").setHeader("firstName").script("jaskel",
"user.firstName").attribute("user", myUser).to("seda:users");
This is a bit different using the Spring DSL where you use the expression
element that doesn't support setting attributes (yet):
L AN G UA GE S S U PP O RTE D A PPE NDIX
246
user.firstName
You can also use predicates e.g. in a Filter:
request.getHeaders().get("Foo").equals("Bar")
See Scripting Languages for the list of languages with explicit DSL support.
Some languages without specific DSL support but known to work with
these generic methods include:
Language
Implementation
language="..." value
BeanShell
BeanShell 2.0b5
beanshell or bsh
Additional arguments to ScriptingEngine
Available as of Camel 2.8
You can provide additional arguments to the ScriptingEngine using a
header on the Camel message with the key CamelScriptArguments.
See this example:
public void testArgumentsExample() throws Exception {
if (!ScriptTestHelper.canRunTestOnThisPlatform()) {
return;
}
getMockEndpoint("mock:result").expectedMessageCount(0);
getMockEndpoint("mock:unmatched").expectedMessageCount(1);
// additional arguments to ScriptEngine
Map arguments = new HashMap();
arguments.put("foo", "bar");
arguments.put("baz", 7);
// those additional arguments is provided as a header on the Camel Message
template.sendBodyAndHeader("direct:start", "hello", ScriptBuilder.ARGUMENTS,
arguments);
assertMockEndpointsSatisfied();
}
247
L A N G UA G E S S U P P ORT E D A P P E N D I X
Using properties function
Available as of Camel 2.9
If you need to use the Properties component from a script to lookup
property placeholders, then its a bit cumbersome to do so.
For example to set a header name myHeader with a value from a property
placeholder, which key is provided in a header named "foo".
.setHeader("myHeader").groovy("context.resolvePropertyPlaceholders('{{' +
request.headers.get('foo') + '}}')")
From Camel 2.9 onwards you can now use the properties function and the
same example is simpler:
.setHeader("myHeader").groovy("properties.resolve(request.headers.get('foo'))")
Dependencies
To use scripting languages in your camel routes you need to add the a
dependency on camel-script which integrates the JSR-223 scripting engine.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-scriptx.x.x
PYTHON
Camel supports Python among other Scripting Languages to allow an
Expression or Predicate to be used in the DSL or Xml Configuration.
To use a Python expression use the following Java code
... python("somePythonExpression") ...
For example you could use the python function to create an Predicate in a
Message Filter or as an Expression for a Recipient List
L AN G UA GE S S U PP O RTE D A PPE NDIX
248
Example
In the sample below we use Python to create a Predicate use in the route
path, to route exchanges from admin users to a special queue.
from("direct:start")
.choice()
.when().python("request.headers['user'] == 'admin'").to("seda:adminQueue")
.otherwise()
.to("seda:regularQueue");
And a Spring DSL sample as well:
request.headers['user'] == 'admin'
ScriptContext
The JSR-223 scripting languages ScriptContext is pre configured with the
following attributes all set at ENGINE_SCOPE:
249
Attribute
Type
Value
context
org.apache.camel.CamelContext
The Camel
Context
exchange
org.apache.camel.Exchange
The
current
Exchange
request
org.apache.camel.Message
The IN
message
response
org.apache.camel.Message
The OUT
message
L A N G UA G E S S U P P ORT E D A P P E N D I X
properties
org.apache.camel.builder.script.PropertiesFunction
Camel
2.9:
Function
with a
resolve
method to
make it
easier to
use
Camels
Properties
component
from
scripts.
See further
below for
example.
Attributes
You can add your own attributes with the attribute(name, value) DSL
method, such as:
In the sample below we add an attribute user that is an object we already
have instantiated as myUser. This object has a getFirstName() method that
we want to set as header on the message. We use the groovy language to
concat the first and last name into a single string that is returned.
from("direct:in").setHeader("name").groovy("'$user.firstName
$user.lastName'").attribute("user", myUser).to("seda:users");
Any scripting language
Camel can run any JSR-223 scripting languages using the script DSL
method such as:
from("direct:in").setHeader("firstName").script("jaskel",
"user.firstName").attribute("user", myUser).to("seda:users");
This is a bit different using the Spring DSL where you use the expression
element that doesn't support setting attributes (yet):
L AN G UA GE S S U PP O RTE D A PPE NDIX
250
user.firstName
You can also use predicates e.g. in a Filter:
request.getHeaders().get("Foo").equals("Bar")
See Scripting Languages for the list of languages with explicit DSL support.
Some languages without specific DSL support but known to work with
these generic methods include:
Language
Implementation
language="..." value
BeanShell
BeanShell 2.0b5
beanshell or bsh
Additional arguments to ScriptingEngine
Available as of Camel 2.8
You can provide additional arguments to the ScriptingEngine using a
header on the Camel message with the key CamelScriptArguments.
See this example:
public void testArgumentsExample() throws Exception {
if (!ScriptTestHelper.canRunTestOnThisPlatform()) {
return;
}
getMockEndpoint("mock:result").expectedMessageCount(0);
getMockEndpoint("mock:unmatched").expectedMessageCount(1);
// additional arguments to ScriptEngine
Map arguments = new HashMap();
arguments.put("foo", "bar");
arguments.put("baz", 7);
// those additional arguments is provided as a header on the Camel Message
template.sendBodyAndHeader("direct:start", "hello", ScriptBuilder.ARGUMENTS,
arguments);
assertMockEndpointsSatisfied();
}
251
L A N G UA G E S S U P P ORT E D A P P E N D I X
Using properties function
Available as of Camel 2.9
If you need to use the Properties component from a script to lookup
property placeholders, then its a bit cumbersome to do so.
For example to set a header name myHeader with a value from a property
placeholder, which key is provided in a header named "foo".
.setHeader("myHeader").groovy("context.resolvePropertyPlaceholders('{{' +
request.headers.get('foo') + '}}')")
From Camel 2.9 onwards you can now use the properties function and the
same example is simpler:
.setHeader("myHeader").groovy("properties.resolve(request.headers.get('foo'))")
Dependencies
To use scripting languages in your camel routes you need to add the a
dependency on camel-script which integrates the JSR-223 scripting engine.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-scriptx.x.x
PHP
Camel supports PHP among other Scripting Languages to allow an Expression
or Predicate to be used in the DSL or Xml Configuration.
To use a PHP expression use the following Java code
... php("somePHPExpression") ...
For example you could use the php function to create an Predicate in a
Message Filter or as an Expression for a Recipient List
L AN G UA GE S S U PP O RTE D A PPE NDIX
252
ScriptContext
The JSR-223 scripting languages ScriptContext is pre configured with the
following attributes all set at ENGINE_SCOPE:
Attribute
Type
Value
context
org.apache.camel.CamelContext
The Camel
Context
exchange
org.apache.camel.Exchange
The
current
Exchange
request
org.apache.camel.Message
The IN
message
response
org.apache.camel.Message
The OUT
message
org.apache.camel.builder.script.PropertiesFunction
Camel
2.9:
Function
with a
resolve
method to
make it
easier to
use
Camels
Properties
component
from
scripts.
See further
below for
example.
properties
Attributes
You can add your own attributes with the attribute(name, value) DSL
method, such as:
In the sample below we add an attribute user that is an object we already
have instantiated as myUser. This object has a getFirstName() method that
we want to set as header on the message. We use the groovy language to
concat the first and last name into a single string that is returned.
253
L A N G UA G E S S U P P ORT E D A P P E N D I X
from("direct:in").setHeader("name").groovy("'$user.firstName
$user.lastName'").attribute("user", myUser).to("seda:users");
Any scripting language
Camel can run any JSR-223 scripting languages using the script DSL
method such as:
from("direct:in").setHeader("firstName").script("jaskel",
"user.firstName").attribute("user", myUser).to("seda:users");
This is a bit different using the Spring DSL where you use the expression
element that doesn't support setting attributes (yet):
user.firstName
You can also use predicates e.g. in a Filter:
request.getHeaders().get("Foo").equals("Bar")
See Scripting Languages for the list of languages with explicit DSL support.
Some languages without specific DSL support but known to work with
these generic methods include:
Language
Implementation
language="..." value
BeanShell
BeanShell 2.0b5
beanshell or bsh
Additional arguments to ScriptingEngine
Available as of Camel 2.8
You can provide additional arguments to the ScriptingEngine using a
header on the Camel message with the key CamelScriptArguments.
See this example:
L AN G UA GE S S U PP O RTE D A PPE NDIX
254
public void testArgumentsExample() throws Exception {
if (!ScriptTestHelper.canRunTestOnThisPlatform()) {
return;
}
getMockEndpoint("mock:result").expectedMessageCount(0);
getMockEndpoint("mock:unmatched").expectedMessageCount(1);
// additional arguments to ScriptEngine
Map arguments = new HashMap();
arguments.put("foo", "bar");
arguments.put("baz", 7);
// those additional arguments is provided as a header on the Camel Message
template.sendBodyAndHeader("direct:start", "hello", ScriptBuilder.ARGUMENTS,
arguments);
assertMockEndpointsSatisfied();
}
Using properties function
Available as of Camel 2.9
If you need to use the Properties component from a script to lookup
property placeholders, then its a bit cumbersome to do so.
For example to set a header name myHeader with a value from a property
placeholder, which key is provided in a header named "foo".
.setHeader("myHeader").groovy("context.resolvePropertyPlaceholders('{{' +
request.headers.get('foo') + '}}')")
From Camel 2.9 onwards you can now use the properties function and the
same example is simpler:
.setHeader("myHeader").groovy("properties.resolve(request.headers.get('foo'))")
Dependencies
To use scripting languages in your camel routes you need to add the a
dependency on camel-script which integrates the JSR-223 scripting engine.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
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org.apache.camelcamel-scriptx.x.x
RUBY
Camel supports Ruby among other Scripting Languages to allow an
Expression or Predicate to be used in the DSL or Xml Configuration.
To use a Ruby expression use the following Java code
... ruby("someRubyExpression") ...
For example you could use the ruby function to create an Predicate in a
Message Filter or as an Expression for a Recipient List
Example
In the sample below we use Ruby to create a Predicate use in the route path,
to route exchanges from admin users to a special queue.
from("direct:start")
.choice()
.when().ruby("$request.headers['user'] == 'admin'").to("seda:adminQueue")
.otherwise()
.to("seda:regularQueue");
And a Spring DSL sample as well:
$request.headers['user'] == 'admin'
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ScriptContext
The JSR-223 scripting languages ScriptContext is pre configured with the
following attributes all set at ENGINE_SCOPE:
Attribute
Type
Value
context
org.apache.camel.CamelContext
The Camel
Context
exchange
org.apache.camel.Exchange
The
current
Exchange
request
org.apache.camel.Message
The IN
message
response
org.apache.camel.Message
The OUT
message
org.apache.camel.builder.script.PropertiesFunction
Camel
2.9:
Function
with a
resolve
method to
make it
easier to
use
Camels
Properties
component
from
scripts.
See further
below for
example.
properties
Attributes
You can add your own attributes with the attribute(name, value) DSL
method, such as:
In the sample below we add an attribute user that is an object we already
have instantiated as myUser. This object has a getFirstName() method that
we want to set as header on the message. We use the groovy language to
concat the first and last name into a single string that is returned.
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from("direct:in").setHeader("name").groovy("'$user.firstName
$user.lastName'").attribute("user", myUser).to("seda:users");
Any scripting language
Camel can run any JSR-223 scripting languages using the script DSL
method such as:
from("direct:in").setHeader("firstName").script("jaskel",
"user.firstName").attribute("user", myUser).to("seda:users");
This is a bit different using the Spring DSL where you use the expression
element that doesn't support setting attributes (yet):
user.firstName
You can also use predicates e.g. in a Filter:
request.getHeaders().get("Foo").equals("Bar")
See Scripting Languages for the list of languages with explicit DSL support.
Some languages without specific DSL support but known to work with
these generic methods include:
Language
Implementation
language="..." value
BeanShell
BeanShell 2.0b5
beanshell or bsh
Additional arguments to ScriptingEngine
Available as of Camel 2.8
You can provide additional arguments to the ScriptingEngine using a
header on the Camel message with the key CamelScriptArguments.
See this example:
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public void testArgumentsExample() throws Exception {
if (!ScriptTestHelper.canRunTestOnThisPlatform()) {
return;
}
getMockEndpoint("mock:result").expectedMessageCount(0);
getMockEndpoint("mock:unmatched").expectedMessageCount(1);
// additional arguments to ScriptEngine
Map arguments = new HashMap();
arguments.put("foo", "bar");
arguments.put("baz", 7);
// those additional arguments is provided as a header on the Camel Message
template.sendBodyAndHeader("direct:start", "hello", ScriptBuilder.ARGUMENTS,
arguments);
assertMockEndpointsSatisfied();
}
Using properties function
Available as of Camel 2.9
If you need to use the Properties component from a script to lookup
property placeholders, then its a bit cumbersome to do so.
For example to set a header name myHeader with a value from a property
placeholder, which key is provided in a header named "foo".
.setHeader("myHeader").groovy("context.resolvePropertyPlaceholders('{{' +
request.headers.get('foo') + '}}')")
From Camel 2.9 onwards you can now use the properties function and the
same example is simpler:
.setHeader("myHeader").groovy("properties.resolve(request.headers.get('foo'))")
Dependencies
To use scripting languages in your camel routes you need to add the a
dependency on camel-script which integrates the JSR-223 scripting engine.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
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org.apache.camelcamel-scriptx.x.x
SIMPLE EXPRESSION LANGUAGE
The Simple Expression Language was a really simple language you can use,
but has since grown more powerful. Its primarily intended for being a really
small and simple language for evaluating Expression and Predicate without
requiring any new dependencies or knowledge of XPath; so its ideal for
testing in camel-core. Its ideal to cover 95% of the common use cases when
you need a little bit of expression based script in your Camel routes.
However for much more complex use cases you are generally
recommended to choose a more expressive and powerful language such as:
• JavaScript
• EL
• OGNL
• Mvel
• Groovy
• one of the supported Scripting Languages
The simple language uses ${body} placeholders for complex expressions
where the expression contains constant literals. The ${ } placeholders can
be omitted if the expression is only the token itself.
To get the body of the in message: "body", or "in.body" or "${body}".
A complex expression must use ${ } placeholders, such as: "Hello
${in.header.name} how are you?".
You can have multiple functions in the same expression: "Hello
${in.header.name} this is ${in.header.me} speaking".
However you can not nest functions in Camel 2.8.x or older (i.e. having
another ${ } placeholder in an existing, is not allowed).
From Camel 2.9 onwards you can nest functions.
Variables
Variable
Type
Description
exchangeId
String
Camel 2.3: the exchange id
id
String
the input message id
body
Object
the input body
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Alternative syntax
From Camel 2.5 onwards you can also use the alternative syntax
which uses $simple{ } as placeholders.
This can be used in situations to avoid clashes when using for
example Spring property placeholder together with Camel.
Configuring result type
From Camel 2.8 onwards you can configure the result type of the
Simple expression. For example to set the type as a
java.lang.Boolean or a java.lang.Integer etc.
File language is now merged with Simple language
From Camel 2.2 onwards, the File Language is now merged with
Simple language which means you can use all the file syntax
directly within the simple language.
Simple Language Changes in Camel 2.9 onwards
The Simple language have been improved from Camel 2.9 onwards
to use a better syntax parser, which can do index precise error
messages, so you know exactly what is wrong and where the
problem is. For example if you have made a typo in one of the
operators, then previously the parser would not be able to detect
this, and cause the evaluation to be true. There is a few changes in
the syntax which are no longer backwards compatible. When using
Simple language as a Predicate then the literal text must be
enclosed in either single or double quotes. For example: "${body}
== 'Camel'". Notice how we have single quotes around the literal.
The old style of using "body" and "header.foo" to refer to the
message body and header is @deprecated, and its encouraged to
always use ${ } tokens for the built-in functions.
The range operator now requires the range to be in single quote as
well as shown: "${header.zip} between '30000..39999'".
in.body
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Object
the input body
L A N G UA G E S S U P P ORT E D A P P E N D I X
body.OGNL
Object
Camel 2.3: the input body invoked
using a Camel OGNL expression.
in.body.OGNL
Object
Camel 2.3: the input body invoked
using a Camel OGNL expression.
Type
Camel 2.3: Converts the body to the
given type determined by its
classname. The converted body can be
null.
mandatoryBodyAs(type)
Type
Camel 2.5: Converts the body to the
given type determined by its
classname, and expects the body to be
not null.
out.body
Object
the output body
header.foo
Object
refer to the input foo header
headers.foo
Object
refer to the input foo header
in.header.foo
Object
refer to the input foo header
in.headers.foo
Object
refer to the input foo header
header.foo[bar]
Object
Camel 2.3: regard input foo header as
a map and perform lookup on the map
with bar as key
in.header.foo[bar]
Object
Camel 2.3: regard input foo header as
a map and perform lookup on the map
with bar as key
in.headers.foo[bar]
Object
Camel 2.3: regard input foo header as
a map and perform lookup on the map
with bar as key
header.foo.OGNL
Object
Camel 2.3: refer to the input foo
header and invoke its value using a
Camel OGNL expression.
in.header.foo.OGNL
Object
Camel 2.3: refer to the input foo
header and invoke its value using a
Camel OGNL expression.
in.headers.foo.OGNL
Object
Camel 2.3: refer to the input foo
header and invoke its value using a
Camel OGNL expression.
out.header.foo
Object
refer to the out header foo
bodyAs(type)
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out.headers.foo
Object
refer to the out header foo
headerAs(key,type)
Type
Camel 2.5: Converts the header to the
given type determined by its
classname
headers
Map
Camel 2.9: refer to the input headers
in.headers
Map
Camel 2.9: refer to the input headers
property.foo
Object
refer to the foo property on the
exchange
property.foo.OGNL
Object
Camel 2.8: refer to the foo property
on the exchange and invoke its value
using a Camel OGNL expression.
sys.foo
String
refer to the system property
sysenv.foo
String
Camel 2.3: refer to the system
environment
exception
Object
Camel 2.4: Refer to the exception
object on the exchange, is null if no
exception set on exchange. Will
fallback and grab caught exceptions
(Exchange.EXCEPTION_CAUGHT) if the
Exchange has any.
exception.OGNL
Object
Camel 2.4: Refer to the exchange
exception invoked using a Camel OGNL
expression object
String
Camel 2.0. Refer to the
exception.message on the exchange, is
null if no exception set on exchange.
Will fallback and grab caught
exceptions
(Exchange.EXCEPTION_CAUGHT) if the
Exchange has any.
String
Camel 2.6. Refer to the
exception.stracktrace on the exchange,
is null if no exception set on exchange.
Will fallback and grab caught
exceptions
(Exchange.EXCEPTION_CAUGHT) if the
Exchange has any.
exception.message
exception.stacktrace
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String
Camel 1.5. Date formatting using the
java.text.SimpleDataFormat
patterns. Supported commands are:
now for current timestamp,
in.header.xxx or header.xxx to use
the Date object in the IN header with
the key xxx. out.header.xxx to use
the Date object in the OUT header with
the key xxx.
Object
Camel 1.5. Invoking a bean
expression using the Bean language.
Specifying a method name you must
use dot as separator. In Camel 2.0 we
also support the
?method=methodname syntax that is
used by the Bean component.
properties:locations:key
String
Camel 2.3: Lookup a property with the
given key. The locations option is
optional. See more at Using
PropertyPlaceholder.
threadName
String
Camel 2.3: Returns the name of the
current thread. Can be used for logging
purpose.
ref:xxx
Object
Camel 2.6: To lookup a bean from the
Registry with the given id.
date:command:pattern
bean:bean expression
OGNL expression support
Available as of Camel 2.3
The Simple and Bean language now supports a Camel OGNL notation for
invoking beans in a chain like fashion.
Suppose the Message IN body contains a POJO which has a getAddress()
method.
Then you can use Camel OGNL notation to access the address object:
simple("${body.address}")
simple("${body.address.street}")
simple("${body.address.zip}")
Camel understands the shorthand names for getters, but you can invoke any
method or use the real name such as:
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simple("${body.address}")
simple("${body.getAddress.getStreet}")
simple("${body.address.getZip}")
simple("${body.doSomething}")
You can also use the null safe operator (?.) to avoid NPE if for example the
body does NOT have an address
simple("${body?.address?.street}")
Its also possible to index in Map or List types, so you can do:
simple("${body[foo].name}")
To assume the body is Map based and lookup the value with foo as key, and
invoke the getName method on that value.
You can access the Map or List objects directly using their key name (with
or without dots) :
simple("${body[foo]}")
simple("${body[this.is.foo]}")
Suppose there was no value with the key foo then you can use the null safe
operator to avoid the NPE as shown:
simple("${body[foo]?.name}")
You can also access List types, for example to get lines from the address
you can do:
simple("${body.address.lines[0]}")
simple("${body.address.lines[1]}")
simple("${body.address.lines[2]}")
There is a special last keyword which can be used to get the last value from
a list.
simple("${body.address.lines[last]}")
And to get the 2nd last you can subtract a number, so we can use last-1 to
indicate this:
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simple("${body.address.lines[last-1]}")
And the 3rd last is of course:
simple("${body.address.lines[last-2]}")
And yes you can combine this with the operator support as shown below:
simple("${body.address.zip} > 1000")
Operator support
Available as of Camel 2.0
We added a basic set of operators supported in the simple language in Camel
2.0. The parser is limited to only support a single operator.
To enable it the left value must be enclosed in ${ }. The syntax is:
${leftValue} OP rightValue
Where the rightValue can be a String literal enclosed in ' ', null, a
constant value or another expression enclosed in ${ }.
Camel will automatically type convert the rightValue type to the leftValue
type, so its able to eg. convert a string into a numeric so you can use >
comparison for numeric values.
The following operators are supported:
Operator
Description
==
equals
>
greater than
>=
greater than or equals
<
less than
<=
less than or equals
!=
not equals
contains
For testing if contains in a string based value
not
contains
For testing if not contains in a string based value
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Important
There must be spaces around the operator.
regex
For matching against a given regular expression pattern
defined as a String value
not regex
For not matching against a given regular expression pattern
defined as a String value
in
For matching if in a set of values, each element must be
separated by comma.
not in
For matching if not in a set of values, each element must be
separated by comma.
is
For matching if the left hand side type is an instanceof the
value.
not is
For matching if the left hand side type is not an instanceof the
value.
range
For matching if the left hand side is within a range of values
defined as numbers: from..to. From Camel 2.9 onwards the
range values must be enclosed in single quotes.
not range
For matching if the left hand side is not within a range of
values defined as numbers: from..to. From Camel 2.9
onwards the range values must be enclosed in single quotes.
And the following unary operators can be used:
Operator
Description
++
Camel 2.9: To increment a number by one.
--
Camel 2.9: To decrement a number by one.
And the following logical operators can be used to group expressions:
267
Operator
Description
and
deprecated use && instead. The logical and operator is used
to group two expressions.
or
deprecated use || instead. The logical or operator is used to
group two expressions.
&&
Camel 2.9: The logical and operator is used to group two
expressions.
L A N G UA G E S S U P P ORT E D A P P E N D I X
||
Camel 2.9: The logical or operator is used to group two
expressions.
The syntax for AND is:
${leftValue} OP rightValue and ${leftValue} OP rightValue
And the syntax for OR is:
${leftValue} OP rightValue or ${leftValue} OP rightValue
Some examples:
simple("${in.header.foo} == 'foo'")
// here Camel will type convert '100' into the type of in.header.bar and if its an
Integer '100' will also be converter to an Integer
simple("${in.header.bar} == '100'")
simple("${in.header.bar} == 100")
// 100 will be converter to the type of in.header.bar so we can do > comparison
simple("${in.header.bar} > 100")
// testing for null
simple("${in.header.baz} == null")
// testing for not null
simple("${in.header.baz} != null")
And a bit more advanced example where the right value is another
expression
simple("${in.header.date} == ${date:now:yyyyMMdd}")
simple("${in.header.type} == ${bean:orderService?method=getOrderType}")
And an example with contains, testing if the title contains the word Camel
simple("${in.header.title} contains 'Camel'")
And an example with regex, testing if the number header is a 4 digit value:
simple("${in.header.number} regex '\d{4}'")
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Using and,or operators
In Camel 2.4 or older the and or or can only be used once in a
simple language expression. From Camel 2.5 onwards you can use
these operators multiple times.
Comparing with different types
When you compare with different types such as String and int, then
you have to take a bit care. Camel will use the type from the left
hand side as 1st priority. And fallback to the right hand side type if
both values couldn't be compared based on that type.
This means you can flip the values to enforce a specific type.
Suppose the bar value above is a String. Then you can flip the
equation:
simple("100 < ${in.header.bar}")
which then ensures the int type is used as 1st priority.
This may change in the future if the Camel team improves the binary
comparison operations to prefer numeric types over String based. It's most
often the String type which causes problem when comparing with numbers.
And finally an example if the header equals any of the values in the list. Each
element must be separated by comma, and no space around.
This also works for numbers etc, as Camel will convert each element into the
type of the left hand side.
simple("${in.header.type} in 'gold,silver'")
And for all the last 3 we also support the negate test using not:
simple("${in.header.type} not in 'gold,silver'")
And you can test if the type is a certain instance, eg for instance a String
simple("${in.header.type} is 'java.lang.String'")
We have added a shorthand for all java.lang types so you can write it as:
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simple("${in.header.type} is 'String'")
Ranges are also supported. The range interval requires numbers and both
from and end are inclusive. For instance to test whether a value is between
100 and 199:
simple("${in.header.number} range 100..199")
Notice we use .. in the range without spaces. Its based on the same syntax
as Groovy.
From Camel 2.9 onwards the range value must be in single quotes
simple("${in.header.number} range '100..199'")
Using and / or
If you have two expressions you can combine them with the and or or
operator.
For instance:
simple("${in.header.title} contains 'Camel' and ${in.header.type'} == 'gold'")
And of course the or is also supported. The sample would be:
simple("${in.header.title} contains 'Camel' or ${in.header.type'} == 'gold'")
Notice: Currently and or or can only be used once in a simple language
expression. This might change in the future.
So you cannot do:
simple("${in.header.title} contains 'Camel' and ${in.header.type'} == 'gold' and
${in.header.number} range 100..200")
Samples
In the Spring XML sample below we filter based on a header value:
in.header.foo
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Can be used in Spring XML
As the Spring XML does not have all the power as the Java DSL with
all its various builder methods, you have to resort to use some
other languages
for testing with simple operators. Now you can do this with the
simple language. In the sample below we want to test if the header
is a widget order:
${in.header.type} == 'widget'
Camel 2.9 onwards
Use && or || from Camel 2.9 onwards.
The Simple language can be used for the predicate test above in the
Message Filter pattern, where we test if the in message has a foo header (a
header with the key foo exists). If the expression evaluates to true then the
message is routed to the mock:foo endpoint, otherwise its lost in the deep
blue sea
.
The same example in Java DSL:
from("seda:orders")
.filter().simple("${in.header.foo}").to("seda:fooOrders");
You can also use the simple language for simple text concatenations such as:
from("direct:hello").transform().simple("Hello ${in.header.user} how are
you?").to("mock:reply");
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Notice that we must use ${ } placeholders in the expression now to allow
Camel to parse it correctly.
And this sample uses the date command to output current date.
from("direct:hello").transform().simple("The today is ${date:now:yyyyMMdd} and its
a great day.").to("mock:reply");
And in the sample below we invoke the bean language to invoke a method on
a bean to be included in the returned string:
from("direct:order").transform().simple("OrderId:
${bean:orderIdGenerator}").to("mock:reply");
Where orderIdGenerator is the id of the bean registered in the Registry. If
using Spring then its the Spring bean id.
If we want to declare which method to invoke on the order id generator
bean we must prepend .method name such as below where we invoke the
generateId method.
from("direct:order").transform().simple("OrderId:
${bean:orderIdGenerator.generateId}").to("mock:reply");
And in Camel 2.0 we can use the ?method=methodname option that we are
familiar with the Bean component itself:
from("direct:order").transform().simple("OrderId:
${bean:orderIdGenerator?method=generateId}").to("mock:reply");
And from Camel 2.3 onwards you can also convert the body to a given type,
for example to ensure its a String you can do:
Hello ${bodyAs(String)} how are you?
There are a few types which have a shorthand notation, so we can use
String instead of java.lang.String. These are: byte[], String,
Integer, Long. All other types must use their FQN name, e.g.
org.w3c.dom.Document.
Its also possible to lookup a value from a header Map in Camel 2.3
onwards:
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The gold value is ${header.type[gold]}
In the code above we lookup the header with name type and regard it as a
java.util.Map and we then lookup with the key gold and return the value.
If the header is not convertible to Map an exception is thrown. If the header
with name type does not exist null is returned.
From Camel 2.9 onwards you can nest functions, such as shown below:
${properties:${header.someKey}}
Setting result type
Available as of Camel 2.8
You can now provide a result type to the Simple expression, which means
the result of the evaluation will be converted to the desired type. This is most
useable to define types such as booleans, integers, etc.
For example to set a header as a boolean type you can do:
.setHeader("cool", simple("true", Boolean.class))
And in XML DSL
true
Changing function start and end tokens
Available as of Camel 2.9
You can configure the function start and end tokens - ${ } using the
methods changeFunctionStartToken and changeFunctionEndToken on
SimpleLanguage, using Java code. From Spring XML you can define a
tag with the new changed tokens in the constructor as shown below:
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In the example above we use [ ] as the changed tokens.
Notice by changing the start/end tokens you change those in all the Camel
applications which share the same camel-core on their classpath.
For example in an OSGi server this may affect many applications, where as a
Web Application as a WAR file it only affects the Web Application.
Dependencies
The Simple language is part of camel-core.
FILE EXPRESSION LANGUAGE
Available as of Camel 1.5
The File Expression Language is an extension to the Simple language, adding
file related capabilities. These capabilities are related to common use cases
working with file path and names. The goal is to allow expressions to be used
with the File and FTP components for setting dynamic file patterns for both
consumer and producer.
Syntax
This language is an extension to the Simple language so the Simple syntax
applies also. So the table below only lists the additional.
As opposed to Simple language File Language also supports Constant
expressions so you can enter a fixed filename.
All the file tokens use the same expression name as the method on the
java.io.File object, for instance file:absolute refers to the
java.io.File.getAbsolute() method. Notice that not all expressions are
supported by the current Exchange. For instance the FTP component
supports some of the options, where as the File component supports all of
them.
Expression
Type
File
Consumer
File
Producer
FTP
Consumer
FTP
Producer
Description
file:name
String
yes
no
yes
no
refers to the file name (is
relative to the starting
directory, see note below)
file:name.ext
String
yes
no
yes
no
Camel 2.3: refers to the file
extension only
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File language is now merged with Simple language
From Camel 2.2 onwards, the file language is now merged with
Simple language which means you can use all the file syntax
directly within the simple language.
file:name.noext
String
yes
no
yes
no
refers to the file name with no
extension (is relative to the
starting directory, see note
below)
file:onlyname
String
yes
no
yes
no
Camel 2.0: refers to the file
name only with no leading
paths.
file:onlyname.noext
String
yes
no
yes
no
Camel 2.0: refers to the file
name only with no extension
and with no leading paths.
file:ext
String
yes
no
yes
no
Camel 1.6.1/Camel 2.0: refers
to the file extension only
file:parent
String
yes
no
yes
no
refers to the file parent
file:path
String
yes
no
yes
no
refers to the file path
file:absolute
Boolean
yes
no
no
no
Camel 2.0: refers to whether
the file is regarded as absolute
or relative
file:absolute.path
String
yes
no
no
no
refers to the absolute file path
file:length
Long
yes
no
yes
no
refers to the file length returned
as a Long type
file:size
Long
yes
no
yes
no
Camel 2.5: refers to the file
length returned as a Long type
file:modified
Date
yes
no
yes
no
Camel 2.0: refers to the file
last modified returned as a Date
type
yes
for date formatting using the
java.text.SimepleDataFormat
patterns. Is an extension to
the Simple language. Additional
command is: file (consumers
only) for the last modified
timestamp of the file. Notice: all
the commands from the Simple
language can also be used.
date:command:pattern
String
yes
yes
yes
File token example
Relative paths
We have a java.io.File handle for the file hello.txt in the following
relative directory: .\filelanguage\test. And we configure our endpoint to
use this starting directory .\filelanguage. The file tokens will return as:
275
Expression
Returns
file:name
test\hello.txt
file:name.ext
txt
L A N G UA G E S S U P P ORT E D A P P E N D I X
file:name.noext
test\hello
file:onlyname
hello.txt
file:onlyname.noext
hello
file:ext
txt
file:parent
filelanguage\test
file:path
filelanguage\test\hello.txt
file:absolute
false
file:absolute.path
\workspace\camel\camelcore\target\filelanguage\test\hello.txt
Absolute paths
We have a java.io.File handle for the file hello.txt in the following
absolute directory: \workspace\camel\camelcore\target\filelanguage\test. And we configure out endpoint to use the
absolute starting directory \workspace\camel\camelcore\target\filelanguage. The file tokens will return as:
Expression
Returns
file:name
test\hello.txt
file:name.ext
txt
file:name.noext
test\hello
file:onlyname
hello.txt
file:onlyname.noext
hello
file:ext
txt
file:parent
\workspace\camel\camelcore\target\filelanguage\test
file:path
\workspace\camel\camelcore\target\filelanguage\test\hello.txt
file:absolute
true
file:absolute.path
\workspace\camel\camelcore\target\filelanguage\test\hello.txt
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Samples
You can enter a fixed Constant expression such as myfile.txt:
fileName="myfile.txt"
Lets assume we use the file consumer to read files and want to move the
read files to backup folder with the current date as a sub folder. This can be
archieved using an expression like:
fileName="backup/${date:now:yyyyMMdd}/${file:name.noext}.bak"
relative folder names are also supported so suppose the backup folder should
be a sibling folder then you can append .. as:
fileName="../backup/${date:now:yyyyMMdd}/${file:name.noext}.bak"
As this is an extension to the Simple language we have access to all the
goodies from this language also, so in this use case we want to use the
in.header.type as a parameter in the dynamic expression:
fileName="../backup/${date:now:yyyyMMdd}/type-${in.header.type}/
backup-of-${file:name.noext}.bak"
If you have a custom Date you want to use in the expression then Camel
supports retrieving dates from the message header.
fileName="orders/
order-${in.header.customerId}-${date:in.header.orderDate:yyyyMMdd}.xml"
And finally we can also use a bean expression to invoke a POJO class that
generates some String output (or convertible to String) to be used:
fileName="uniquefile-${bean:myguidgenerator.generateid}.txt"
And of course all this can be combined in one expression where you can use
the File Language, Simple and the Bean language in one combined
expression. This is pretty powerful for those common file path patterns.
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Using Spring PropertyPlaceholderConfigurer together with the File
component
In Camel you can use the File Language directly from the Simple language
which makes a Content Based Router easier to do in Spring XML, where we
can route based on file extensions as shown below:
${file:ext} == 'txt'${file:ext} == 'xml'
If you use the fileName option on the File endpoint to set a dynamic
filename using the File Language then make sure you
use the alternative syntax (available from Camel 2.5 onwards) to avoid
clashing with Springs PropertyPlaceholderConfigurer.
Listing 21. bundle-context.xml
Listing 22. bundle-context.cfg
fromEndpoint=activemq:queue:test
toEndpoint=file://fileRoute/out?fileName=test-$simple{date:now:yyyyMMdd}.txt
Notice how we use the $simple{ } syntax in the toEndpoint above.
If you don't do this, there is a clash and Spring will throw an exception like
org.springframework.beans.factory.BeanDefinitionStoreException:
Invalid bean definition with name 'sampleRoute' defined in class path resource
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[bundle-context.xml]:
Could not resolve placeholder 'date:now:yyyyMMdd'
Dependencies
The File language is part of camel-core.
SQL
The SQL support is added by JoSQL and is primarily used for performing SQL
queries on in-memory objects. If you prefer to perform actual database
queries then check out the JPA component.
To use SQL in your camel routes you need to add the a dependency on
camel-josql which implements the SQL language.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-josql2.5.0
Camel supports SQL to allow an Expression or Predicate to be used in the
DSL or Xml Configuration. For example you could use SQL to create an
Predicate in a Message Filter or as an Expression for a Recipient List.
from("queue:foo").setBody().sql("select * from MyType").to("queue:bar")
And the spring DSL:
select * from MyType
Variables
Variable
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Type
Description
L A N G UA G E S S U P P ORT E D A P P E N D I X
exchange
Exchange
the Exchange object
in
Message
the exchange.in message
out
Message
the exchange.out message
the
property
key
Object
the Exchange properties
the header
key
Object
the exchange.in headers
the variable
key
Object
if any additional variables is added using
setVariables method
XPATH
Camel supports XPath to allow an Expression or Predicate to be used in the
DSL or Xml Configuration. For example you could use XPath to create an
Predicate in a Message Filter or as an Expression for a Recipient List.
from("queue:foo").
filter().xpath("//foo")).
to("queue:bar")
from("queue:foo").
choice().xpath("//foo")).to("queue:bar").
otherwise().to("queue:others");
Namespaces
In 1.3 onwards you can easily use namespaces with XPath expressions using
the Namespaces helper class.
Namespaces ns = new Namespaces("c", "http://acme.com/cheese");
from("direct:start").filter().
xpath("/c:person[@name='James']", ns).
to("mock:result");
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Variables
Variables in XPath is defined in different namespaces. The default namespace
is http://camel.apache.org/schema/spring.
Namespace URI
Local
part
Type
Description
http://camel.apache.org/xml/in/
in
Message
the exchange.in
message
Message
the
exchange.out
message
http://camel.apache.org/xml/out/
out
http://camel.apache.org/xml/
functions/
functions
Object
Camel 2.5:
Additional
functions
http://camel.apache.org/xml/
variables/environment-variables
env
Object
OS environment
variables
http://camel.apache.org/xml/
variables/system-properties
system
Object
Java System
properties
Object
the exchange
property
http://camel.apache.org/xml/
variables/exchange-property
Camel will resolve variables according to either:
▪ namespace given
▪ no namespace given
Namespace given
If the namespace is given then Camel is instructed exactly what to return.
However when resolving either in or out Camel will try to resolve a header
with the given local part first, and return it. If the local part has the value
body then the body is returned instead.
No namespace given
If there is no namespace given then Camel resolves only based on the local
part. Camel will try to resolve a variable in the following steps:
▪ from variables that has been set using the variable(name,
value) fluent builder
▪ from message.in.header if there is a header with the given key
▪ from exchange.properties if there is a property with the given key
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Functions
Camel adds the following XPath functions that can be used to access the
exchange:
Function
Argument
Type
Description
in:body
none
Object
Will return the in message
body.
in:header
the header
name
Object
Will return the in message
header.
out:body
none
Object
Will return the out message
body.
out:header
the header
name
Object
Will return the out message
header.
function:properties
key for
property
String
Camel 2.5: To lookup a
property using the Properties
component (property
placeholders).
function:simple
simple
expression
Object
Camel 2.5: To evaluate a
Simple expression.
Notice: function:properties and function:simple is not supported when
the return type is a NodeSet, such as when using with a Splitter EIP.
Here's an example showing some of these functions in use.
from("direct:start").choice()
.when().xpath("in:header('foo') = 'bar'").to("mock:x")
.when().xpath("in:body() = ''").to("mock:y")
.otherwise().to("mock:z");
And the new functions introduced in Camel 2.5:
// setup properties component
PropertiesComponent properties = new PropertiesComponent();
properties.setLocation("classpath:org/apache/camel/builder/xml/myprop.properties");
context.addComponent("properties", properties);
// myprop.properties contains the following properties
// foo=Camel
// bar=Kong
from("direct:in").choice()
// $type is a variable for the header with key type
// here we use the properties function to lookup foo from the properties files
// which at runtime will be evaluted to 'Camel'
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.when().xpath("$type = function:properties('foo')")
.to("mock:camel")
// here we use the simple language to evaluate the expression
// which at runtime will be evaluated to 'Donkey Kong'
.when().xpath("//name = function:simple('Donkey ${properties:bar}')")
.to("mock:donkey")
.otherwise()
.to("mock:other")
.end();
Using XML configuration
If you prefer to configure your routes in your Spring XML file then you can
use XPath expressions as follows
/foo:person[@name='James']
Notice how we can reuse the namespace prefixes, foo in this case, in the
XPath expression for easier namespace based XPath expressions!
See also this discussion on the mailinglist about using your own
namespaces with xpath
Setting result type
The XPath expression will return a result type using native XML objects such
as org.w3c.dom.NodeList. But many times you want a result type to be a
String. To do this you have to instruct the XPath which result type to use.
In Java DSL:
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L A N G UA G E S S U P P ORT E D A P P E N D I X
xpath("/foo:person/@id", String.class)
In Spring DSL you use the resultType attribute to provide a fully qualified
classname:
/foo:person/@id
In @XPath:
Available as of Camel 2.1
@XPath(value = "concat('foo-',//order/name/)", resultType = String.class) String name)
Where we use the xpath function concat to prefix the order name with foo-.
In this case we have to specify that we want a String as result type so the
concat function works.
Examples
Here is a simple example using an XPath expression as a predicate in a
Message Filter
from("direct:start").
filter().xpath("/person[@name='James']").
to("mock:result");
If you have a standard set of namespaces you wish to work with and wish to
share them across many different XPath expressions you can use the
NamespaceBuilder as shown in this example
// lets define the namespaces we'll need in our filters
Namespaces ns = new Namespaces("c", "http://acme.com/cheese")
.add("xsd", "http://www.w3.org/2001/XMLSchema");
// now lets create an xpath based Message Filter
from("direct:start").
filter(ns.xpath("/c:person[@name='James']")).
to("mock:result");
In this sample we have a choice construct. The first choice evaulates if the
message has a header key type that has the value Camel.
The 2nd choice evaluates if the message body has a name tag
which values is Kong.
If neither is true the message is routed in the otherwise block:
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from("direct:in").choice()
// using $headerName is special notation in Camel to get the header key
.when().xpath("$type = 'Camel'")
.to("mock:camel")
// here we test for the body name tag
.when().xpath("//name = 'Kong'")
.to("mock:donkey")
.otherwise()
.to("mock:other")
.end();
And the spring XML equivalent of the route:
$type = 'Camel'//name = 'Kong'
XPATH INJECTION
You can use Bean Integration to invoke a method on a bean and use various
languages such as XPath to extract a value from the message and bind it to a
method parameter.
The default XPath annotation has SOAP and XML namespaces available. If
you want to use your own namespace URIs in an XPath expression you can
use your own copy of the XPath annotation to create whatever namespace
prefixes you want to use.
import
import
import
import
285
java.lang.annotation.ElementType;
java.lang.annotation.Retention;
java.lang.annotation.RetentionPolicy;
java.lang.annotation.Target;
L A N G UA G E S S U P P ORT E D A P P E N D I X
import org.w3c.dom.NodeList;
import org.apache.camel.component.bean.XPathAnnotationExpressionFactory;
import org.apache.camel.language.LanguageAnnotation;
import org.apache.camel.language.NamespacePrefix;
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER})
@LanguageAnnotation(language = "xpath", factory =
XPathAnnotationExpressionFactory.class)
public @interface MyXPath {
String value();
// You can add the namespaces as the default value of the annotation
NamespacePrefix[] namespaces() default {
@NamespacePrefix(prefix = "n1", uri = "http://example.org/ns1"),
@NamespacePrefix(prefix = "n2", uri = "http://example.org/ns2")};
Class resultType() default NodeList.class;
}
i.e. cut and paste upper code to your own project in a different package and/
or annotation name then add whatever namespace prefix/uris you want in
scope when you use your annotation on a method parameter. Then when you
use your annotation on a method parameter all the namespaces you want
will be available for use in your XPath expression.
NOTE this feature is supported from Camel 1.6.1.
For example
public class Foo {
@MessageDriven(uri = "activemq:my.queue")
public void doSomething(@MyXPath("/ns1:foo/ns2:bar/text()") String correlationID,
@Body String body) {
// process the inbound message here
}
}
Using XPathBuilder without an Exchange
Available as of Camel 2.3
You can now use the org.apache.camel.builder.XPathBuilder without
the need for an Exchange. This comes handy if you want to use it as a helper
to do custom xpath evaluations.
It requires that you pass in a CamelContext since a lot of the moving parts
inside the XPathBuilder requires access to the Camel Type Converter and
hence why CamelContext is needed.
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For example you can do something like this:
boolean matches = XPathBuilder.xpath("/foo/bar/@xyz").matches(context, ""));
This will match the given predicate.
You can also evaluate for example as shown in the following three
examples:
String name = XPathBuilder.xpath("foo/bar").evaluate(context,
"cheese", String.class);
Integer number = XPathBuilder.xpath("foo/bar").evaluate(context,
"123", Integer.class);
Boolean bool = XPathBuilder.xpath("foo/bar").evaluate(context,
"true", Boolean.class);
Evaluating with a String result is a common requirement and thus you can do
it a bit simpler:
String name = XPathBuilder.xpath("foo/bar").evaluate(context,
"cheese");
Using Saxon with XPathBuilder
Available as of Camel 2.3
You need to add camel-saxon as dependency to your project.
Its now easier to use Saxon with the XPathBuilder which can be done in
several ways as shown below.
Where as the latter ones are the easiest ones.
Using a factory
// create a Saxon factory
XPathFactory fac = new net.sf.saxon.xpath.XPathFactoryImpl();
// create a builder to evaluate the xpath using the saxon factory
XPathBuilder builder = XPathBuilder.xpath("tokenize(/foo/bar, '_')[2]").factory(fac);
// evaluate as a String result
String result = builder.evaluate(context, "abc_def_ghi");
assertEquals("def", result);
Using ObjectModel
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// create a builder to evaluate the xpath using saxon based on its object model uri
XPathBuilder builder = XPathBuilder.xpath("tokenize(/foo/bar,
'_')[2]").objectModel("http://saxon.sf.net/jaxp/xpath/om");
// evaluate as a String result
String result = builder.evaluate(context, "abc_def_ghi");
assertEquals("def", result);
The easy one
// create a builder to evaluate the xpath using saxon
XPathBuilder builder = XPathBuilder.xpath("tokenize(/foo/bar, '_')[2]").saxon();
// evaluate as a String result
String result = builder.evaluate(context, "abc_def_ghi");
assertEquals("def", result);
Setting a custom XPathFactory using System Property
Available as of Camel 2.3
Camel now supports reading the JVM system property
javax.xml.xpath.XPathFactory that can be used to set a custom
XPathFactory to use.
This unit test shows how this can be done to use Saxon instead:
// set system property with the XPath factory to use which is Saxon
System.setProperty(XPathFactory.DEFAULT_PROPERTY_NAME + ":" + "http://saxon.sf.net/
jaxp/xpath/om", "net.sf.saxon.xpath.XPathFactoryImpl");
// create a builder to evaluate the xpath using saxon
XPathBuilder builder = XPathBuilder.xpath("tokenize(/foo/bar, '_')[2]");
// evaluate as a String result
String result = builder.evaluate(context, "abc_def_ghi");
assertEquals("def", result);
Camel will log at INFO level if it uses a non default XPathFactory such as:
XPathBuilder INFO Using system property
javax.xml.xpath.XPathFactory:http://saxon.sf.net/jaxp/xpath/om with value:
net.sf.saxon.xpath.XPathFactoryImpl when creating XPathFactory
Dependencies
The XPath language is part of camel-core.
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XQUERY
Camel supports XQuery to allow an Expression or Predicate to be used in the
DSL or Xml Configuration. For example you could use XQuery to create an
Predicate in a Message Filter or as an Expression for a Recipient List.
Options
Name
Default Value
Description
allowStAX
false
Camel 2.8.3/2.9: Whether to allow using StAX as the javax.xml.transform.Source.
Examples
from("queue:foo").filter().
xquery("//foo").
to("queue:bar")
You can also use functions inside your query, in which case you need an
explicit type conversion (or you will get a org.w3c.dom.DOMException:
HIERARCHY_REQUEST_ERR) by passing the Class as a second argument to
the xquery() method.
from("direct:start").
recipientList().xquery("concat('mock:foo.', /person/@city)", String.class);
Variables
The IN message body will be set as the contextItem. Besides this these
Variables is also added as parameters:
Type
Description
exchange
Exchange
The current Exchange
in.body
Object
The In message's body
>=
1.6.1
out.body
Object
The OUT message's body (if any)
>=
1.6.1
Object
You can access the value of
exchange.in.headers with key foo
by using the variable which name is
in.headers.foo
>=1.6.1
in.headers.*
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Support
version
Variable
L A N G UA G E S S U P P ORT E D A P P E N D I X
out.headers.*
key name
Object
You can access the value of
exchange.out.headers with key foo
by using the variable which name is
out.headers.foo variable
Object
Any exchange.properties and
exchange.in.headers
(exchange.in.headers support was
removed since camel 1.6.1) and
any additional parameters set
using setParameters(Map). These
parameters is added with they own
key name, for instance if there is an
IN header with the key name foo
then its added as foo.
>=1.6.1
Using XML configuration
If you prefer to configure your routes in your Spring XML file then you can
use XPath expressions as follows
/foo:person[@name='James']
Notice how we can reuse the namespace prefixes, foo in this case, in the
XPath expression for easier namespace based XQuery expressions!
When you use functions in your XQuery expression you need an explicit
type conversion which is done in the xml configuration via the @type
attribute:
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concat('mock:foo.', /person/@city)
Using XQuery as an endpoint
Sometimes an XQuery expression can be quite large; it can essentally be
used for Templating. So you may want to use an XQuery Endpoint so you can
route using XQuery templates.
The following example shows how to take a message of an ActiveMQ
queue (MyQueue) and transform it using XQuery and send it to MQSeries.
Examples
Here is a simple example using an XQuery expression as a predicate in a
Message Filter
from("direct:start").filter().xquery("/person[@name='James']").to("mock:result");
This example uses XQuery with namespaces as a predicate in a Message
Filter
Namespaces ns = new Namespaces("c", "http://acme.com/cheese");
from("direct:start").
filter().xquery("/c:person[@name='James']", ns).
to("mock:result");
Learning XQuery
XQuery is a very powerful language for querying, searching, sorting and
returning XML. For help learning XQuery try these tutorials
• Mike Kay's XQuery Primer
• the W3Schools XQuery Tutorial
You might also find the XQuery function reference useful
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Dependencies
To use XQuery in your camel routes you need to add the a dependency on
camel-saxon which implements the XQuery language.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-saxon1.4.0
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Data Format Appendix
DATA FORMAT
Camel supports a pluggable DataFormat to allow messages to be marshalled
to and from binary or text formats to support a kind of Message Translator.
The following data formats are currently supported:
• Standard JVM object marshalling
◦ Serialization
◦ String
• Object marshalling
◦ JSON
◦ Protobuf
• Object/XML marshalling
◦ Castor
◦ JAXB
◦ XmlBeans
◦ XStream
◦ JiBX
• Object/XML/Webservice marshalling
◦ SOAP
• Flat data structure marshalling
◦ Bindy
◦ CSV
◦ EDI
◦ Flatpack DataFormat
• Domain specific marshalling
◦ HL7 DataFormat
• Compression
◦ GZip data format
◦ Zip DataFormat
• Security
◦ Crypto
◦ PGP
◦ XMLSecurity DataFormat
• Misc.
◦ Custom DataFormat - to use your own custom
implementation
◦ TidyMarkup
◦ Syslog
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D ATA F O R MAT A P P E N D I X
And related is the following Type Converters:
▪ Dozer Type Conversion
Unmarshalling
If you receive a message from one of the Camel Components such as File,
HTTP or JMS you often want to unmarshal the payload into some bean so that
you can process it using some Bean Integration or perform Predicate
evaluation and so forth. To do this use the unmarshal word in the DSL in
Java or the Xml Configuration.
For example
DataFormat jaxb = new JaxbDataFormat("com.acme.model");
from("activemq:My.Queue").
unmarshal(jaxb).
to("mqseries:Another.Queue");
The above uses a named DataFormat of jaxb which is configured with a
number of Java package names. You can if you prefer use a named reference
to a data format which can then be defined in your Registry such as via your
Spring XML file.
You can also use the DSL itself to define the data format as you use it. For
example the following uses Java serialization to unmarshal a binary file then
send it as an ObjectMessage to ActiveMQ
from("file://foo/bar").
unmarshal().serialization().
to("activemq:Some.Queue");
Marshalling
Marshalling is the opposite of unmarshalling, where a bean is marshalled into
some binary or textual format for transmission over some transport via a
Camel Component. Marshalling is used in the same way as unmarshalling
above; in the DSL you can use a DataFormat instance, you can configure the
DataFormat dynamically using the DSL or you can refer to a named instance
of the format in the Registry.
The following example unmarshals via serialization then marshals using a
named JAXB data format to perform a kind of Message Translator
from("file://foo/bar").
unmarshal().serialization().
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marshal("jaxb").
to("activemq:Some.Queue");
Using Spring XML
This example shows how to configure the data type just once and reuse it on
multiple routes
You can also define reusable data formats as Spring beans
SERIALIZATION
Serialization is a Data Format which uses the standard Java Serialization
mechanism to unmarshal a binary payload into Java objects or to marshal
Java objects into a binary blob.
For example the following uses Java serialization to unmarshal a binary file
then send it as an ObjectMessage to ActiveMQ
from("file://foo/bar").
unmarshal().serialization().
to("activemq:Some.Queue");
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D ATA F O R MAT A P P E N D I X
Dependencies
This data format is provided in camel-core so no additional dependencies is
needed.
JAXB
JAXB is a Data Format which uses the JAXB2 XML marshalling standard which
is included in Java 6 to unmarshal an XML payload into Java objects or to
marshal Java objects into an XML payload.
Using the Java DSL
For example the following uses a named DataFormat of jaxb which is
configured with a number of Java package names to initialize the
JAXBContext.
DataFormat jaxb = new JaxbDataFormat("com.acme.model");
from("activemq:My.Queue").
unmarshal(jaxb).
to("mqseries:Another.Queue");
You can if you prefer use a named reference to a data format which can then
be defined in your Registry such as via your Spring XML file. e.g.
from("activemq:My.Queue").
unmarshal("myJaxbDataType").
to("mqseries:Another.Queue");
Using Spring XML
The following example shows how to use JAXB to unmarshal using Spring
configuring the jaxb data type
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This example shows how to configure the data type just once and reuse it on
multiple routes. For Camel versions below 1.5.0 you have to set the
element directly in .
Partial marshalling/unmarshalling
This feature is new to Camel 2.2.0.
JAXB 2 supports marshalling and unmarshalling XML tree fragments. By
default JAXB looks for @XmlRootElement annotation on given class to operate
on whole XML tree. This is useful but not always - sometimes generated code
does not have @XmlRootElement annotation, sometimes you need
unmarshall only part of tree.
In that case you can use partial unmarshalling. To enable this behaviours you
need set property partClass. Camel will pass this class to JAXB's
unmarshaler.
For marshalling you have to add partNamespace attribute with QName of
destination namespace. Example of Spring DSL you can find above.
Fragment
This feature is new to Camel 2.8.0.
JaxbDataFormat has new property fragment which can set the the
Marshaller.JAXB_FRAGMENT encoding property on the JAXB Marshaller. If you
don't want the JAXB Marshaller to generate the XML declaration, you can set
this option to be true. The default value of this property is fales.
Ignoring the NonXML Character
This feature is new to Camel 2.2.0.
JaxbDataFromat supports to ignore the NonXML Character, you just need to
set the filterNonXmlChars property to be true, JaxbDataFormat will replace
the NonXML character with " " when it is marshaling or unmarshaling the
message. You can also do it by setting the Exchange property
Exchange.FILTER_NON_XML_CHARS.
JDK 1.5
JDK 1.6+
Filtering in use
StAX API and implementation
No
Filtering not in use
StAX API only
No
This feature has been tested with Woodstox 3.2.9 and Sun JDK 1.6 StAX
implementation.
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Working with the ObjectFactory
If you use XJC to create the java class from the schema, you will get an
ObjectFactory for you JAXB context. Since the ObjectFactory uses
JAXBElement to hold the reference of the schema and element instance
value, from Camel 1.5.1 jaxbDataformat will ignore the JAXBElement by
default and you will get the element instance value instead of the
JAXBElement object form the unmarshaled message body.
If you want to get the JAXBElement object form the unmarshaled message
body, you need to set the JaxbDataFormat object's ignoreJAXBElement
property to be false.
Setting encoding
In Camel 1.6.1 and newer you can set the encoding option to use when
marshalling. Its the Marshaller.JAXB_ENCODING encoding property on the
JAXB Marshaller.
You can setup which encoding to use when you declare the JAXB data format.
You can also provide the encoding in the Exchange property
Exchange.CHARSET_NAME. This property will overrule the encoding set on the
JAXB data format.
In this Spring DSL we have defined to use iso-8859-1 as the encoding:
Dependencies
To use JAXB in your camel routes you need to add the a dependency on
camel-jaxb which implements this data format.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-jaxb
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1.6.0
XMLBEANS
XmlBeans is a Data Format which uses the XmlBeans library to unmarshal an
XML payload into Java objects or to marshal Java objects into an XML
payload.
from("activemq:My.Queue").
unmarshal().xmlBeans().
to("mqseries:Another.Queue");
Dependencies
To use XmlBeans in your camel routes you need to add the dependency on
camel-xmlbeans which implements this data format.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-xmlbeans2.8.0
XSTREAM
XStream is a Data Format which uses the XStream library to marshal and
unmarshal Java objects to and from XML.
// lets turn Object messages into XML then send to MQSeries
from("activemq:My.Queue").
marshal().xstream().
to("mqseries:Another.Queue");
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XMLInputFactory and XMLOutputFactory
The XStream library uses the javax.xml.stream.XMLInputFactory and
javax.xml.stream.XMLOutputFactory, you can control which
implementation of this factory should be used.
The Factory is discovered using this algorithm:
1. Use the javax.xml.stream.XMLInputFactory ,
javax.xml.stream.XMLOutputFactory system property.
2. Use the lib/xml.stream.properties file in the JRE_HOME directory.
3. Use the Services API, if available, to determine the classname by looking in
the META-INF/services/javax.xml.stream.XMLInputFactory, META-INF/
services/javax.xml.stream.XMLOutputFactory files in jars available to
the JRE.
4. Use the platform default XMLInputFactory,XMLOutputFactory instance.
How to set the XML encoding in Xstream DataFormat?
From Camel 1.6.3 or Camel 2.2.0, you can set the encoding of XML in
Xstream DataFormat by setting the Exchange's property with the key
Exchange.CHARSET_NAME, or setting the encoding property on Xstream from
DSL or Spring config.
from("activemq:My.Queue").
marshal().xstream("UTF-8").
to("mqseries:Another.Queue");
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Dependencies
To use XStream in your camel routes you need to add the a dependency on
camel-xstream which implements this data format.
If you use maven you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-xstream1.5.0
CSV
The CSV Data Format uses Apache Commons CSV to handle CSV payloads
(Comma Separated Values) such as those exported/imported by Excel.
Options
Option
Type
Description
config
CSVConfig
Can be used to set a custom CSVConfig
object.
strategy
CSVStrategy
Camel uses by default
CSVStrategy.DEFAULT_STRATEGY.
autogenColumn
boolean
Camel 1.6.1/2.0: Is default true. By
default, columns are autogenerated in
the resulting CSV. Subsequent messages
use the previously created columns with
new fields being added at the end of the
line.
delimiter
String
Camel 2.4: Is default ,. Can be used to
configure the delimiter, if it's not the
comma.
Marshalling a Map to CSV
The component allows you to marshal a Java Map (or any other message
type that can be converted in a Map) into a CSV payload.
An example: if you send a message with this map...
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Map body = new HashMap();
body.put("foo", "abc");
body.put("bar", 123);
... through this route ...
from("direct:start").
marshal().csv().
to("mock:result");
... you will end up with a String containing this CSV message
abc,123
Sending the Map below through this route will result in a CSV message that
looks like foo,bar
Unmarshalling a CSV message into a Java List
Unmarshalling will transform a CSV messsage into a Java List with CSV file
lines (containing another List with all the field values).
An example: we have a CSV file with names of persons, their IQ and their
current activity.
Jack Dalton, 115, mad at Averell
Joe Dalton, 105, calming Joe
William Dalton, 105, keeping Joe from killing Averell
Averell Dalton, 80, playing with Rantanplan
Lucky Luke, 120, capturing the Daltons
We can now use the CSV component to unmarshal this file:
from("file:src/test/resources/?fileName=daltons.csv&noop=true").
unmarshal().csv().
to("mock:daltons");
The resulting message will contain a List> like...
List> data = (List>) exchange.getIn().getBody();
for (List line : data) {
LOG.debug(String.format("%s has an IQ of %s and is currently %s",
line.get(0), line.get(1), line.get(2)));
}
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Marshalling a List tag
make sure you put the endpoint you want to filter (, etc.) before the closing tag or the filter
will not be applied (in 2.8+, omitting this will result in an error)
In the example below we do not want to route messages any further that
has the word Bye in the message body. Notice how we prevent this in the
when predicate by using the .stop().
from("direct:start")
.choice()
.when(body().contains("Hello")).to("mock:hello")
.when(body().contains("Bye")).to("mock:bye").stop()
.otherwise().to("mock:other")
.end()
.to("mock:result");
Knowing if Exchange was filtered or not
Available as of Camel 2.5
The Message Filter EIP will add a property on the Exchange which states if
it was filtered or not.
The property has the key Exchannge.FILTER_MATCHED which has the
String value of CamelFilterMatched. Its value is a boolean indicating true or
false. If the value is true then the Exchange was routed in the filter block.
Using This Pattern
If you would like to use this EIP Pattern then please read the Getting Started,
you may also find the Architecture useful particularly the description of
Endpoint and URIs. Then you could try out some of the Examples first before
trying this pattern out.
DYNAMIC ROUTER
The Dynamic Router from the EIP patterns allows you to route messages
while avoiding the dependency of the router on all possible destinations
while maintaining its efficiency.
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In Camel 2.5 we introduced a dynamicRouter in the DSL which is like a
dynamic Routing Slip which evaluates the slip on-the-fly.
Options
Name
Default
Value
Description
uriDelimiter
,
Delimiter used if the Expression returned multiple endpoints.
ignoreInvalidEndpoints
false
If an endpoint uri could not be resolved, should it be ignored. Otherwise Camel will thrown an
exception stating the endpoint uri is not valid.
Dynamic Router in Camel 2.5 onwards
From Camel 2.5 the Dynamic Router will set a property
(Exchange.SLIP_ENDPOINT) on the Exchange which contains the current
endpoint as it advanced though the slip. This allows you to know how far we
have processed in the slip. (It's a slip because the Dynamic Router
implementation is based on top of Routing Slip).
Java DSL
In Java DSL you can use the dynamicRouter as shown below:
from("direct:start")
// use a bean as the dynamic router
.dynamicRouter(bean(DynamicRouterTest.class, "slip"));
Which will leverage a Bean to compute the slip on-the-fly, which could be
implemented as follows:
/**
* Use this method to compute dynamic where we should route next.
*
* @param body the message body
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Beware
You must ensure the expression used for the dynamicRouter such
as a bean, will return null to indicate the end. Otherwise the
dynamicRouter will keep repeating endlessly.
* @return endpoints to go, or null to indicate the end
*/
public String slip(String body) {
bodies.add(body);
invoked++;
if (invoked == 1) {
return "mock:a";
} else if (invoked == 2) {
return "mock:b,mock:c";
} else if (invoked == 3) {
return "direct:foo";
} else if (invoked == 4) {
return "mock:result";
}
// no more so return null
return null;
}
Mind that this example is only for show and tell. The current implementation
is not thread safe. You would have to store the state on the Exchange, to
ensure thread safety.
Spring XML
The same example in Spring XML would be:
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Bye World
@DynamicRouter annotation
You can also use the @DynamicRouter annotation, for example the Camel 2.4
example below could be written as follows. The route method would then be
invoked repeatedly as the message is processed dynamically. The idea is to
return the next endpoint uri where to go. Return null to indicate the end. You
can return multiple endpoints if you like, just as the Routing Slip, where each
endpoint is separated by a delimiter.
public class MyDynamicRouter {
@Consume(uri = "activemq:foo")
@DynamicRouter
public String route(@XPath("/customer/id") String customerId, @Header("Location")
String location, Document body) {
// query a database to find the best match of the endpoint based on the input
parameteres
// return the next endpoint uri, where to go. Return null to indicate the end.
}
}
Dynamic Router in Camel 2.4 or older
The simplest way to implement this is to use the RecipientList Annotation on
a Bean method to determine where to route the message.
public class MyDynamicRouter {
@Consume(uri = "activemq:foo")
@RecipientList
public List route(@XPath("/customer/id") String customerId,
@Header("Location") String location, Document body) {
// query a database to find the best match of the endpoint based on the input
parameteres
...
}
}
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In the above we can use the Parameter Binding Annotations to bind different
parts of the Message to method parameters or use an Expression such as
using XPath or XQuery.
The method can be invoked in a number of ways as described in the Bean
Integration such as
• POJO Producing
• Spring Remoting
• Bean component
Using This Pattern
If you would like to use this EIP Pattern then please read the Getting Started,
you may also find the Architecture useful particularly the description of
Endpoint and URIs. Then you could try out some of the Examples first before
trying this pattern out.
Recipient List
The Recipient List from the EIP patterns allows you to route messages to a
number of dynamically specified recipients.
The recipients will receive a copy of the same Exchange and Camel will
execute them sequentially.
Options
Name
Default
Value
Description
delimiter
,
Delimiter used if the Expression returned multiple endpoints.
Refers to an AggregationStrategy to be used to assemble the replies from the recipients, into a
single outgoing message from the Recipient List. By default Camel will use the last reply as the
outgoing message.
strategyRef
parallelProcessing
executorServiceRef
false
Camel 2.2: If enables then sending messages to the recipients occurs concurrently. Note the
caller thread will still wait until all messages has been fully processed, before it continues. Its only
the sending and processing the replies from the recipients which happens concurrently.
Camel 2.2: Refers to a custom Thread Pool to be used for parallel processing. Notice if you set this
option, then parallel processing is automatic implied, and you do not have to enable that option as
well.
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stopOnException
false
Camel 2.2: Whether or not to stop continue processing immediately when an exception occurred.
If disable, then Camel will send the message to all recipients regardless if one of them failed. You
can deal with exceptions in the AggregationStrategy class where you have full control how to
handle that.
ignoreInvalidEndpoints
false
Camel 2.3: If an endpoint uri could not be resolved, should it be ignored. Otherwise Camel will
thrown an exception stating the endpoint uri is not valid.
streaming
false
Camel 2.5: If enabled then Camel will process replies out-of-order, eg in the order they come
back. If disabled, Camel will process replies in the same order as the Expression specified.
timeout
Camel 2.5: Sets a total timeout specified in millis. If the Recipient List hasn't been able to send
and process all replies within the given timeframe, then the timeout triggers and the Recipient List
breaks out and continues. Notice if you provide a TimeoutAwareAggregationStrategy then the
timeout method is invoked before breaking out.
onPrepareRef
Camel 2.8: Refers to a custom Processor to prepare the copy of the Exchange each recipient will
receive. This allows you to do any custom logic, such as deep-cloning the message payload if
that's needed etc.
shareUnitOfWork
false
Camel 2.8: Whether the unit of work should be shared. See the same option on Splitter for more
details.
Static Recipient List
The following example shows how to route a request from an input queue:a
endpoint to a static list of destinations
Using Annotations
You can use the RecipientList Annotation on a POJO to create a Dynamic
Recipient List. For more details see the Bean Integration.
Using the Fluent Builders
RouteBuilder builder = new RouteBuilder() {
public void configure() {
errorHandler(deadLetterChannel("mock:error"));
from("seda:a")
.multicast().to("seda:b", "seda:c", "seda:d");
}
};
Using the Spring XML Extensions
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Dynamic Recipient List
Usually one of the main reasons for using the Recipient List pattern is that
the list of recipients is dynamic and calculated at runtime. The following
example demonstrates how to create a dynamic recipient list using an
Expression (which in this case it extracts a named header value dynamically)
to calculate the list of endpoints which are either of type Endpoint or are
converted to a String and then resolved using the endpoint URIs.
Using the Fluent Builders
RouteBuilder builder = new RouteBuilder() {
public void configure() {
errorHandler(deadLetterChannel("mock:error"));
from("seda:a")
.recipientList(header("foo"));
}
};
The above assumes that the header contains a list of endpoint URIs. The
following takes a single string header and tokenizes it
from("direct:a").recipientList(
header("recipientListHeader").tokenize(","));
Iteratable value
The dynamic list of recipients that are defined in the header must be
iteratable such as:
▪ java.util.Collection
▪ java.util.Iterator
▪ arrays
▪ org.w3c.dom.NodeList
▪ Camel 1.6.0: a single String with values separated with comma
▪ any other type will be regarded as a single value
Using the Spring XML Extensions
$foo
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For further examples of this pattern in use you could look at one of the junit
test case
Using delimiter in Spring XML
Available as of Camel 1.6.0
In Spring DSL you can set the delimiter attribute for setting a delimiter to
be used if the header value is a single String with multiple separated
endpoints. By default Camel uses comma as delimiter, but this option lets
you specify a customer delimiter to use instead.
myHeader
So if myHeader contains a String with the value "activemq:queue:foo,
activemq:topic:hello , log:bar" then Camel will split the String using
the delimiter given in the XML that was comma, resulting into 3 endpoints to
send to. You can use spaces between the endpoints as Camel will trim the
value when it lookup the endpoint to send to.
Note: In Java DSL you use the tokenizer to archive the same. The route
above in Java DSL:
from("direct:a").recipientList(header("myHeader").tokenize(","));
In Camel 2.1 its a bit easier as you can pass in the delimiter as 2nd
parameter:
from("direct:a").recipientList(header("myHeader"), "#");
Sending to multiple recipients in parallel
Available as of Camel 2.2
The Recipient List now supports parallelProcessing that for example
Splitter also supports. You can use it to use a thread pool to have concurrent
tasks sending the Exchange to multiple recipients concurrently.
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from("direct:a").recipientList(header("myHeader")).parallelProcessing();
And in Spring XML its an attribute on the recipient list tag.
myHeader
Stop continuing in case one recipient failed
Available as of Camel 2.2
The Recipient List now supports stopOnException that for example
Splitter also supports. You can use it to stop sending to any further recipients
in case any recipient failed.
from("direct:a").recipientList(header("myHeader")).stopOnException();
And in Spring XML its an attribute on the recipient list tag.
myHeader
Note: You can combine parallelProcessing and stopOnException and
have them both true.
Ignore invalid endpoints
Available as of Camel 2.3
The Recipient List now supports ignoreInvalidEndpoints which the
Routing Slip also supports. You can use it to skip endpoints which is invalid.
from("direct:a").recipientList(header("myHeader")).ignoreInvalidEndpoints();
And in Spring XML its an attribute on the recipient list tag.
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myHeader
Then lets say the myHeader contains the following two endpoints
direct:foo,xxx:bar. The first endpoint is valid and works. However the 2nd
is invalid and will just be ignored. Camel logs at INFO level about, so you can
see why the endpoint was invalid.
Using custom AggregationStrategy
Available as of Camel 2.2
You can now use you own AggregationStrategy with the Recipient List.
However its not that often you need that. What its good for is that in case
you are using Request Reply messaging then the replies from the recipient
can be aggregated. By default Camel uses UseLatestAggregationStrategy
which just keeps that last received reply. What if you must remember all the
bodies that all the recipients send back, then you can use your own custom
aggregator that keeps those. Its the same principle as with the Aggregator
EIP so check it out for details.
from("direct:a")
.recipientList(header("myHeader")).aggregationStrategy(new
MyOwnAggregationStrategy())
.to("direct:b");
And in Spring XML its an attribute on the recipient list tag.
myHeader
Using custom thread pool
Available as of Camel 2.2
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A thread pool is only used for parallelProcessing. You supply your own
custom thread pool via the ExecutorServiceStrategy (see Camel's
Threading Model), the same way you would do it for the
aggregationStrategy. By default Camel uses a thread pool with 10 threads
(subject to change in a future version).
Using method call as recipient list
You can use a Bean to provide the recipients, for example:
from("activemq:queue:test").recipientList().method(MessageRouter.class, "routeTo");
And then MessageRouter:
public class MessageRouter {
public String routeTo() {
String queueName = "activemq:queue:test2";
return queueName;
}
}
When you use a Bean then do not also use the @RecipientList annotation
as this will in fact add yet another recipient list, so you end up having two.
Do not do like this.
public class MessageRouter {
@RecipientList
public String routeTo() {
String queueName = "activemq:queue:test2";
return queueName;
}
}
Well you should only do like that above (using @RecipientList) if you route
just route to a Bean which you then want to act as a recipient list.
So the original route can be changed to:
from("activemq:queue:test").bean(MessageRouter.class, "routeTo");
Which then would invoke the routeTo method and detect its annotated with
@RecipientList and then act accordingly as if it was a recipient list EIP.
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Using timeout
Available as of Camel 2.5
If you use parallelProcessing then you can configure a total timeout
value in millis. Camel will then process the messages in parallel until the
timeout is hit. This allows you to continue processing if one message is slow.
For example you can set a timeout value of 20 sec.
For example in the unit test below you can see we multicast the message
to 3 destinations. We have a timeout of 2 seconds, which means only the last
two messages can be completed within the timeframe. This means we will
only aggregate the last two which yields a result aggregation which outputs
"BC".
from("direct:start")
.multicast(new AggregationStrategy() {
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
if (oldExchange == null) {
return newExchange;
}
String body = oldExchange.getIn().getBody(String.class);
oldExchange.getIn().setBody(body +
newExchange.getIn().getBody(String.class));
return oldExchange;
}
})
.parallelProcessing().timeout(250).to("direct:a", "direct:b", "direct:c")
// use end to indicate end of multicast route
.end()
.to("mock:result");
from("direct:a").delay(1000).to("mock:A").setBody(constant("A"));
from("direct:b").to("mock:B").setBody(constant("B"));
from("direct:c").to("mock:C").setBody(constant("C"));
By default if a timeout occurs the AggregationStrategy is not invoked.
However you can implement a specialized version
public interface TimeoutAwareAggregationStrategy extends AggregationStrategy {
/**
* A timeout occurred
*
* @param oldExchange the oldest exchange (is null on first aggregation
as we only have the new exchange)
* @param index
the index
* @param total
the total
* @param timeout
the timeout value in millis
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Timeout in other EIPs
This timeout feature is also supported by Splitter and both
multicast and recipientList.
*/
void timeout(Exchange oldExchange, int index, int total, long timeout);
This allows you to deal with the timeout in the AggregationStrategy if you
really need to.
Using onPrepare to execute custom logic when preparing messages
Available as of Camel 2.8
See details at Multicast
Using This Pattern
If you would like to use this EIP Pattern then please read the Getting Started,
you may also find the Architecture useful particularly the description of
Endpoint and URIs. Then you could try out some of the Examples first before
trying this pattern out.
Splitter
The Splitter from the EIP patterns allows you split a message into a number
of pieces and process them individually
As of Camel 2.0, you need to specify a Splitter as split(). In earlier
versions of Camel, you need to use splitter().
Options
Name
Default
Value
Description
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Timeout is total
The timeout is total, which means that after X time, Camel will
aggregate the messages which has completed within the
timeframe. The remainders will be cancelled. Camel will also only
invoke the timeout method in the
TimeoutAwareAggregationStrategy once, for the first index which
caused the timeout.
Refers to an AggregationStrategy to be used to assemble the replies from the sub-messages, into a
single outgoing message from the Splitter. See the section titled What does the splitter return below for
whats used by default.
strategyRef
parallelProcessing
false
If enables then processing the sub-messages occurs concurrently. Note the caller thread will still wait
until all sub-messages has been fully processed, before it continues.
Refers to a custom Thread Pool to be used for parallel processing. Notice if you set this option, then
parallel processing is automatic implied, and you do not have to enable that option as well.
executorServiceRef
stopOnException
false
Camel 2.2: Whether or not to stop continue processing immediately when an exception occurred. If
disable, then Camel continue splitting and process the sub-messages regardless if one of them failed.
You can deal with exceptions in the AggregationStrategy class where you have full control how to
handle that.
streaming
false
If enabled then Camel will split in a streaming fashion, which means it will split the input message in
chunks. This reduces the memory overhead. For example if you split big messages its recommended to
enable streaming. If streaming is enabled then the sub-message replies will be aggregated out-of-order,
eg in the order they come back. If disabled, Camel will process sub-message replies in the same order
as they where splitted.
timeout
Camel 2.5: Sets a total timeout specified in millis. If the Recipient List hasn't been able to split and
process all replies within the given timeframe, then the timeout triggers and the Splitter breaks out and
continues. Notice if you provide a TimeoutAwareAggregationStrategy then the timeout method is
invoked before breaking out.
onPrepareRef
Camel 2.8: Refers to a custom Processor to prepare the sub-message of the Exchange, before its
processed. This allows you to do any custom logic, such as deep-cloning the message payload if that's
needed etc.
shareUnitOfWork
false
Camel 2.8: Whether the unit of work should be shared. See further below for more details.
Exchange properties
The following properties is set on each Exchange that are split:
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header
type
description
CamelSplitIndex
int
Camel 2.0: A split counter that increases
for each Exchange being split. The
counter starts from 0.
CamelSplitSize
int
Camel 2.0: The total number of
Exchanges that was splitted. This header
is not applied for stream based splitting.
From Camel 2.9 onwards this header is
also set in stream based splitting, but
only on the completed Exchange.
CamelSplitComplete
boolean
Camel 2.4: Whether or not this
Exchange is the last.
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Examples
The following example shows how to take a request from the queue:a
endpoint the split it into pieces using an Expression, then forward each piece
to queue:b
Using the Fluent Builders
RouteBuilder builder = new RouteBuilder() {
public void configure() {
errorHandler(deadLetterChannel("mock:error"));
from("seda:a")
.split(body(String.class).tokenize("\n"))
.to("seda:b");
}
};
The splitter can use any Expression language so you could use any of the
Languages Supported such as XPath, XQuery, SQL or one of the Scripting
Languages to perform the split. e.g.
from("activemq:my.queue").split(xpath("//foo/
bar")).convertBodyTo(String.class).to("file://some/directory")
Using the Spring XML Extensions
/invoice/lineItems
For further examples of this pattern in use you could look at one of the junit
test case
Using Tokenizer from Spring XML Extensions*
Avaiaible as of Camel 2.0
You can use the tokenizer expression in the Spring DSL to split bodies or
headers using a token. This is a common use-case, so we provided a special
tokenizer tag for this.
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In the sample below we split the body using a @ as separator. You can of
course use comma or space or even a regex pattern, also set regex=true.
Splitting the body in Spring XML is a bit harder as you need to use the Simple
language to dictate this
${body}
What does the splitter return?
Camel 2.2 or older:
The Splitter will by default return the last splitted message.
Camel 2.3 and newer
The Splitter will by default return the original input message.
For all versions
You can override this by suppling your own strategy as an
AggregationStrategy. There is a sample on this page (Split aggregate
request/reply sample). Notice its the same strategy as the Aggregator
supports. This Splitter can be viewed as having a build in light weight
Aggregator.
Parallel execution of distinct 'parts'
If you want to execute all parts in parallel you can use special notation of
split() with two arguments, where the second one is a boolean flag if
processing should be parallel. e.g.
XPathBuilder xPathBuilder = new XPathBuilder("//foo/bar");
from("activemq:my.queue").split(xPathBuilder, true).to("activemq:my.parts");
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In Camel 2.0 the boolean option has been refactored into a builder method
parallelProcessing so its easier to understand what the route does when
we use a method instead of true|false.
XPathBuilder xPathBuilder = new XPathBuilder("//foo/bar");
from("activemq:my.queue").split(xPathBuilder).parallelProcessing().to("activemq:my.parts");
Stream based
You can split streams by enabling the streaming mode using the streaming
builder method.
from("direct:streaming").split(body().tokenize(",")).streaming().to("activemq:my.parts");
You can also supply your custom splitter to use with streaming like this:
import static org.apache.camel.builder.ExpressionBuilder.beanExpression;
from("direct:streaming")
.split(beanExpression(new MyCustomIteratorFactory(), "iterator"))
.streaming().to("activemq:my.parts")
Streaming big XML payloads using Tokenizer language
Available as of Camel 2.9
If you have a big XML payload, from a file source, and want to split it in
streaming mode, then you can use the Tokenizer language with start/end
tokens to do this with low memory footprint. For example you may have a
XML payload structured as follows
...
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Splitting big XML payloads
The XPath engine in Java and saxon will load the entire XML content
into memory. And thus they are not well suited for very big XML
payloads.
Instead you can use a custom Expression which will iterate the XML
payload in a streamed fashion. From Camel 2.9 onwards you can
use the Tokenizer language
which supports this when you supply the start and end tokens.
Now to split this big file using XPath would cause the entire content to be
loaded into memory. So instead we can use the Tokenizer language to do this
as follows:
from("file:inbox")
.split().tokenizeXML("order").streaming()
.to("activemq:queue:order");
In XML DSL the route would be as follows:
Notice the tokenizeXML method which will split the file using the tag name
of the child node, which mean it will grab the content between the
and tags (incl. the tokens). So for example a splitted message
would be as follows:
If you want to inherit namespaces from a root/parent tag, then you can do
this as well by providing the name of the root/parent tag:
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And in Java DSL its as follows:
from("file:inbox")
.split().tokenizeXML("order", "orders").streaming()
.to("activemq:queue:order");
Specifying a custom aggregation strategy
Available as of Camel 2.0
This is specified similar to the Aggregator.
Specifying a custom ThreadPoolExecutor
You can customize the underlying ThreadPoolExecutor used in the parallel
splitter. In the Java DSL try something like this:
XPathBuilder xPathBuilder = new XPathBuilder("//foo/bar");
ExecutorService pool = ...
from("activemq:my.queue")
.split(xPathBuilder).parallelProcessing().executorService(pool)
.to("activemq:my.parts");
Using a Pojo to do the splitting
As the Splitter can use any Expression to do the actual splitting we leverage
this fact and use a method expression to invoke a Bean to get the splitted
parts.
The Bean should return a value that is iterable such as:
java.util.Collection, java.util.Iterator or an array.
In the route we define the Expression as a method call to invoke our Bean
that we have registered with the id mySplitterBean in the Registry.
from("direct:body")
// here we use a POJO bean mySplitterBean to do the split of the payload
.split().method("mySplitterBean", "splitBody")
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.to("mock:result");
from("direct:message")
// here we use a POJO bean mySplitterBean to do the split of the message
// with a certain header value
.split().method("mySplitterBean", "splitMessage")
.to("mock:result");
And the logic for our Bean is as simple as. Notice we use Camel Bean Binding
to pass in the message body as a String object.
public class MySplitterBean {
/**
* The split body method returns something that is iteratable such as a
java.util.List.
*
* @param body the payload of the incoming message
* @return a list containing each part splitted
*/
public List splitBody(String body) {
// since this is based on an unit test you can of cause
// use different logic for splitting as Camel have out
// of the box support for splitting a String based on comma
// but this is for show and tell, since this is java code
// you have the full power how you like to split your messages
List answer = new ArrayList();
String[] parts = body.split(",");
for (String part : parts) {
answer.add(part);
}
return answer;
}
/**
* The split message method returns something that is iteratable such as a
java.util.List.
*
* @param header the header of the incoming message with the name user
* @param body the payload of the incoming message
* @return a list containing each part splitted
*/
public List splitMessage(@Header(value = "user") String header, @Body
String body) {
// we can leverage the Parameter Binding Annotations
// http://camel.apache.org/parameter-binding-annotations.html
// to access the message header and body at same time,
// then create the message that we want, splitter will
// take care rest of them.
// *NOTE* this feature requires Camel version >= 1.6.1
List answer = new ArrayList();
String[] parts = header.split(",");
for (String part : parts) {
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DefaultMessage message = new DefaultMessage();
message.setHeader("user", part);
message.setBody(body);
answer.add(message);
}
return answer;
}
}
Split aggregate request/reply sample
This sample shows how you can split an Exchange, process each splitted
message, aggregate and return a combined response to the original caller
using request/reply.
The route below illustrates this and how the split supports a
aggregationStrategy to hold the in progress processed messages:
// this routes starts from the direct:start endpoint
// the body is then splitted based on @ separator
// the splitter in Camel supports InOut as well and for that we need
// to be able to aggregate what response we need to send back, so we provide our
// own strategy with the class MyOrderStrategy.
from("direct:start")
.split(body().tokenize("@"), new MyOrderStrategy())
// each splitted message is then send to this bean where we can process it
.to("bean:MyOrderService?method=handleOrder")
// this is important to end the splitter route as we do not want to do more
routing
// on each splitted message
.end()
// after we have splitted and handled each message we want to send a single
combined
// response back to the original caller, so we let this bean build it for us
// this bean will receive the result of the aggregate strategy: MyOrderStrategy
.to("bean:MyOrderService?method=buildCombinedResponse")
And the OrderService bean is as follows:
public static class MyOrderService {
private static int counter;
/**
* We just handle the order by returning a id line for the order
*/
public String handleOrder(String line) {
LOG.debug("HandleOrder: " + line);
return "(id=" + ++counter + ",item=" + line + ")";
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}
/**
* We use the same bean for building the combined response to send
* back to the original caller
*/
public String buildCombinedResponse(String line) {
LOG.debug("BuildCombinedResponse: " + line);
return "Response[" + line + "]";
}
}
And our custom aggregationStrategy that is responsible for holding the in
progress aggregated message that after the splitter is ended will be sent to
the buildCombinedResponse method for final processing before the
combined response can be returned to the waiting caller.
/**
* This is our own order aggregation strategy where we can control
* how each splitted message should be combined. As we do not want to
* loos any message we copy from the new to the old to preserve the
* order lines as long we process them
*/
public static class MyOrderStrategy implements AggregationStrategy {
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
// put order together in old exchange by adding the order from new exchange
if (oldExchange == null) {
// the first time we aggregate we only have the new exchange,
// so we just return it
return newExchange;
}
String orders = oldExchange.getIn().getBody(String.class);
String newLine = newExchange.getIn().getBody(String.class);
LOG.debug("Aggregate old orders: " + orders);
LOG.debug("Aggregate new order: " + newLine);
// put orders together separating by semi colon
orders = orders + ";" + newLine;
// put combined order back on old to preserve it
oldExchange.getIn().setBody(orders);
// return old as this is the one that has all the orders gathered until now
return oldExchange;
}
}
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So lets run the sample and see how it works.
We send an Exchange to the direct:start endpoint containing a IN body with
the String value: A@B@C. The flow is:
HandleOrder: A
HandleOrder: B
Aggregate old orders: (id=1,item=A)
Aggregate new order: (id=2,item=B)
HandleOrder: C
Aggregate old orders: (id=1,item=A);(id=2,item=B)
Aggregate new order: (id=3,item=C)
BuildCombinedResponse: (id=1,item=A);(id=2,item=B);(id=3,item=C)
Response to caller: Response[(id=1,item=A);(id=2,item=B);(id=3,item=C)]
Stop processing in case of exception
Available as of Camel 2.1
The Splitter will by default continue to process the entire Exchange even in
case of one of the splitted message will thrown an exception during routing.
For example if you have an Exchange with 1000 rows that you split and route
each sub message. During processing of these sub messages an exception is
thrown at the 17th. What Camel does by default is to process the remainder
983 messages. You have the chance to remedy or handle this in the
AggregationStrategy.
But sometimes you just want Camel to stop and let the exception be
propagated back, and let the Camel error handler handle it. You can do this in
Camel 2.1 by specifying that it should stop in case of an exception occurred.
This is done by the stopOnException option as shown below:
from("direct:start")
.split(body().tokenize(",")).stopOnException()
.process(new MyProcessor())
.to("mock:split");
And using XML DSL you specify it as follows:
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Using onPrepare to execute custom logic when preparing messages
Available as of Camel 2.8
See details at Multicast
Sharing unit of work
Available as of Camel 2.8
The Splitter will by default not share unit of work between the parent
exchange and each splitted exchange. This means each sub exchange has its
own individual unit of work.
For example you may have an use case, where you want to split a big
message. And you want to regard that process as an atomic isolated
operation that either is a success or failure. In case of a failure you want that
big message to be moved into a dead letter queue. To support this use case,
you would have to share the unit of work on the Splitter.
Here is an example in Java DSL
errorHandler(deadLetterChannel("mock:dead").useOriginalMessage()
.maximumRedeliveries(3).redeliveryDelay(0));
from("direct:start")
.to("mock:a")
// share unit of work in the splitter, which tells Camel to propagate failures
from
// processing the splitted messages back to the result of the splitter, which
allows
// it to act as a combined unit of work
.split(body().tokenize(",")).shareUnitOfWork()
.to("mock:b")
.to("direct:line")
.end()
.to("mock:result");
from("direct:line")
.to("log:line")
.process(new MyProcessor())
.to("mock:line");
Now in this example what would happen is that in case there is a problem
processing each sub message, the error handler will kick in (yes error
handling still applies for the sub messages). But what doesn't happen is that
if a sub message fails all redelivery attempts (its exhausted), then its not
moved into that dead letter queue. The reason is that we have shared the
unit of work, so the sub message will report the error on the shared unit of
work. When the Splitter is done, it checks the state of the shared unit of work
and checks if any errors occurred. And if an error occurred it will set the
exception on the Exchange and mark it for rollback. The error handler will yet
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again kick in, as the Exchange has been marked as rollback and it had an
exception as well. No redelivery attempts is performed (as it was marked for
rollback) and the Exchange will be moved into the dead letter queue.
Using this from XML DSL is just as easy as you just have to set the
shareUnitOfWork attribute to true:
Using This Pattern
If you would like to use this EIP Pattern then please read the Getting Started,
you may also find the Architecture useful particularly the description of
Endpoint and URIs. Then you could try out some of the Examples first before
trying this pattern out.
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Implementation of shared unit of work in Camel 2.x
The Camel team had to introduce a SubUnitOfWork to keep API
compatible with the current UnitOfWork in Camel 2.x code base. So
in reality the unit of work is not shared as a single object instance.
Instead SubUnitOfWork is attached to their parent, and issues
callback to the parent about their status (commit or rollback). This
may be refactored in Camel 3.0 where larger API changes can be
done.
Aggregator
This applies for Camel version 2.3 or newer. If you use an older
version then use this Aggregator link instead.
The Aggregator from the EIP patterns allows you to combine a number of
messages together into a single message.
A correlation Expression is used to determine the messages which should
be aggregated together. If you want to aggregate all messages into a single
message, just use a constant expression. An AggregationStrategy is used to
combine all the message exchanges for a single correlation key into a single
message exchange.
Aggregator options
The aggregator supports the following options:
Option
419
Default
Description
correlationExpression
Mandatory Expression which evaluates the correlation key to use for aggregation. The
Exchange which has the same correlation key is aggregated together. If the correlation
key could not be evaluated an Exception is thrown. You can disable this by using the
ignoreBadCorrelationKeys option.
aggregationStrategy
Mandatory AggregationStrategy which is used to merge the incoming Exchange with
the existing already merged exchanges. At first call the oldExchange parameter is null.
On subsequent invocations the oldExchange contains the merged exchanges and
newExchange is of course the new incoming Exchange.
strategyRef
A reference to lookup the AggregationStrategy in the Registry.
completionSize
Number of messages aggregated before the aggregation is complete. This option can be
set as either a fixed value or using an Expression which allows you to evaluate a size
dynamically - will use Integer as result. If both are set Camel will fallback to use the fixed
value if the Expression result was null or 0.
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completionTimeout
Time in millis that an aggregated exchange should be inactive before its complete. This
option can be set as either a fixed value or using an Expression which allows you to
evaluate a timeout dynamically - will use Long as result. If both are set Camel will fallback
to use the fixed value if the Expression result was null or 0. You cannot use this option
together with completionInterval, only one of the two can be used.
completionInterval
A repeating period in millis by which the aggregator will complete all current aggregated
exchanges. Camel has a background task which is triggered every period. You cannot use
this option together with completionTimeout, only one of them can be used.
completionPredicate
A Predicate to indicate when an aggregated exchange is complete.
completionFromBatchConsumer
false
This option is if the exchanges are coming from a Batch Consumer. Then when enabled
the Aggregator2 will use the batch size determined by the Batch Consumer in the
message header CamelBatchSize. See more details at Batch Consumer. This can be used
to aggregate all files consumed from a File endpoint in that given poll.
forceCompletionOnStop
false
Camel 2.9 Indicates to complete all current aggregated exchanges when the context is
stopped
false
Whether or not to eager check for completion when a new incoming Exchange has been
received. This option influences the behavior of the completionPredicate option as the
Exchange being passed in changes accordingly. When false the Exchange passed in the
Predicate is the aggregated Exchange which means any information you may store on the
aggregated Exchange from the AggregationStrategy is available for the Predicate. When
true the Exchange passed in the Predicate is the incoming Exchange, which means you
can access data from the incoming Exchange.
groupExchanges
false
If enabled then Camel will group all aggregated Exchanges into a single combined
org.apache.camel.impl.GroupedExchange holder class that holds all the aggregated
Exchanges. And as a result only one Exchange is being sent out from the aggregator. Can
be used to combine many incoming Exchanges into a single output Exchange without
coding a custom AggregationStrategy yourself.
ignoreInvalidCorrelationKeys
false
Whether or not to ignore correlation keys which could not be evaluated to a value. By
default Camel will throw an Exception, but you can enable this option and ignore the
situation instead.
eagerCheckCompletion
Whether or not too late Exchanges should be accepted or not. You can enable this to
indicate that if a correlation key has already been completed, then any new exchanges
with the same correlation key be denied. Camel will then throw a
closedCorrelationKeyException exception. When using this option you pass in a
integer which is a number for a LRUCache which keeps that last X number of closed
correlation keys. You can pass in 0 or a negative value to indicate a unbounded cache. By
passing in a number you are ensured that cache won't grow too big if you use a log of
different correlation keys.
closeCorrelationKeyOnCompletion
discardOnCompletionTimeout
false
Camel 2.5: Whether or not exchanges which complete due to a timeout should be
discarded. If enabled then when a timeout occurs the aggregated message will not be
sent out but dropped (discarded).
aggregationRepository
Allows you to plugin you own implementation of
org.apache.camel.spi.AggregationRepository which keeps track of the current
inflight aggregated exchanges. Camel uses by default a memory based implementation.
aggregationRepositoryRef
Reference to lookup a aggregationRepository in the Registry.
parallelProcessing
false
When aggregated are completed they are being send out of the aggregator. This option
indicates whether or not Camel should use a thread pool with multiple threads for
concurrency. If no custom thread pool has been specified then Camel creates a default
pool with 10 concurrent threads.
executorService
If using parallelProcessing you can specify a custom thread pool to be used. In fact
also if you are not using parallelProcessing this custom thread pool is used to send out
aggregated exchanges as well.
executorServiceRef
Reference to lookup a executorService in the Registry
timeoutCheckerExecutorService
Camel 2.9: If using either of the completionTimeout, completionTimeoutExpression,
or completionInterval options a background thread is created to check for the
completion for every aggregator. Set this option to provide a custom thread pool to be
used rather than creating a new thread for every aggregator.
timeoutCheckerExecutorServiceRef
Camel 2.9: Reference to lookup a timeoutCheckerExecutorService in the Registry
Exchange Properties
The following properties are set on each aggregated Exchange:
header
type
description
CamelAggregatedSize
int
The total number of Exchanges aggregated into this combined Exchange.
CamelAggregatedCompletedBy
String
Indicator how the aggregation was completed as a value of either: predicate, size, consumer,
timeout or interval.
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About AggregationStrategy
The AggregationStrategy is used for aggregating the old (lookup by its
correlation id) and the new exchanges together into a single exchange.
Possible implementations include performing some kind of combining or
delta processing, such as adding line items together into an invoice or just
using the newest exchange and removing old exchanges such as for state
tracking or market data prices; where old values are of little use.
Notice the aggregation strategy is a mandatory option and must be
provided to the aggregator.
Here are a few example AggregationStrategy implementations that should
help you create your own custom strategy.
//simply combines Exchange String body values using '+' as a delimiter
class StringAggregationStrategy implements AggregationStrategy {
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
if (oldExchange == null) {
return newExchange;
}
String oldBody = oldExchange.getIn().getBody(String.class);
String newBody = newExchange.getIn().getBody(String.class);
oldExchange.getIn().setBody(oldBody + "+" + newBody);
return oldExchange;
}
}
//simply combines Exchange body values into an ArrayList
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Debug logging
This component has log level TRACE that can be helpful if you have
problems.
See Also
•
•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
File2
CAMEL COMPONENTS FOR GOOGLE APP ENGINE
The Camel components for Google App Engine (GAE) are part of the camelgae project and provide connectivity to GAE's cloud computing services. They
make the GAE cloud computing environment accessible to applications via
Camel interfaces. Following this pattern for other cloud computing
environments could make it easier to port Camel applications from one cloud
computing provider to another. The following table lists the cloud computing
services provided by Google and the supporting Camel components. The
documentation of each component can be found by following the link in the
Camel Component column.
GAE
service
Camel
component
Component description
URL fetch
service
ghttp
Provides connectivity to the GAE URL fetch service but can also be used to receive messages from
servlets.
Task
queueing
service
gtask
Supports asynchronous message processing on GAE by using the task queueing service as message
queue.
Mail service
gmail
Supports sending of emails via the GAE mail service. Receiving mails is not supported yet but will be
added later.
Memcache
service
Not supported yet.
XMPP service
Not supported yet.
Images
service
Not supported yet.
Datastore
service
Not supported yet.
Accounts
service
These components interact with the Google Accounts API for authentication and authorization. Google
Accounts is not specific to Google App Engine but is often used by GAE applications for implementing
security. The gauth component is used by web applications to implement a Google-specific OAuth
consumer. This component can also be used to OAuth-enable non-GAE web applications. The glogin
component is used by Java clients (outside GAE) for programmatic login to GAE applications. For
instructions how to protect GAE applications against unauthorized access refer to the Security for Camel
GAE applications page.
gauth
glogin
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Tutorials
• A good starting point for using Camel on GAE is the Tutorial
for Camel on Google App Engine
• The OAuth tutorial demonstrates how to implement OAuth
in web applications.
Camel context
Setting up a SpringCamelContext on Google App Engine differs between
Camel 2.1 and higher versions. The problem is that usage of the Camelspecific Spring configuration XML schema from the
http://camel.apache.org/schema/spring namespace requires JAXB and
Camel 2.1 depends on a Google App Engine SDK version that doesn't support
JAXB yet. This limitation has been removed since Camel 2.2.
JMX must be disabled in any case because the javax.management package
isn't on the App Engine JRE whitelist.
Camel 2.1
camel-gae 2.1 comes with the following CamelContext implementations.
• org.apache.camel.component.gae.context.GaeDefaultCamelContext
(extends org.apache.camel.impl.DefaultCamelContext)
• org.apache.camel.component.gae.context.GaeSpringCamelContext
(extends org.apache.camel.spring.SpringCamelContext)
Both disable JMX before startup. The GaeSpringCamelContext additionally
provides setter methods adding route builders as shown in the next example.
Listing 75. appctx.xml
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Alternatively, use the routeBuilders property of the
GaeSpringCamelContext for setting a list of route builders. Using this
approach, a SpringCamelContext can be configured on GAE without the
need for JAXB.
Camel 2.2 or higher
With Camel 2.2 or higher, applications can use the
http://camel.apache.org/schema/spring namespace for configuring a
SpringCamelContext but still need to disable JMX. Here's an example.
Listing 76. appctx.xml
The web.xml
Running Camel on GAE requires usage of the CamelHttpTransportServlet
from camel-servlet. The following example shows how to configure this
servlet together with a Spring application context XML file.
Listing 77. web.xml
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CamelServletorg.apache.camel.component.servlet.CamelHttpTransportServletcontextConfigLocationappctx.xmlCamelServlet/camel/*CamelServlet/worker/*
The location of the Spring application context XML file is given by the
contextConfigLocation init parameter. The appctx.xml file must be on the
classpath. The servlet mapping makes the Camel application accessible
under http://.appspot.com/camel/... when deployed to
Google App Engine where must be replaced by a real GAE
application name. The second servlet mapping is used internally by the task
queueing service for background processing via web hooks. This mapping is
relevant for the gtask component and is explained there in more detail.
HAZELCAST COMPONENT
Available as of Camel 2.7
The hazelcast: component allows you to work with the Hazelcast
distributed data grid / cache. Hazelcast is a in memory data grid, entirely
written in Java (single jar). It offers a great palette of different data stores like
map, multi map (same key, n values), queue, list and atomic number. The
main reason to use Hazelcast is its simple cluster support. If you have
enabled multicast on your network you can run a cluster with hundred nodes
with no extra configuration. Hazelcast can simply configured to add
additional features like n copies between nodes (default is 1), cache
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persistence, network configuration (if needed), near cache, enviction and so
on. For more information consult the Hazelcast documentation on
http://www.hazelcast.com/documentation.jsp.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-hazelcastx.x.x
URI format
hazelcast:[ map | multimap | queue | seda | set | atomicvalue |
instance]:cachename[?options]
Sections
1.
2.
3.
4.
5.
6.
7.
Usage
Usage
Usage
Usage
Usage
Usage
Usage
of
of
of
of
of
of
of
map
multimap
queue
list
seda
atomic number
cluster support (instance)
Usage of Map
map cache producer - to("hazelcast:map:foo")
If you want to store a value in a map you can use the map cache producer.
The map cache producer provides 5 operations (put, get, update, delete,
query). For the first 4 you have to provide the operation inside the
"hazelcast.operation.type" header variable. In Java DSL you can use the
constants from
org.apache.camel.component.hazelcast.HazelcastConstants.
Header Variables for the request message:
Name
Type
Description
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You have to use the second prefix to define which type of data store
you want to use.
hazelcast.operation.type
String
valid values are: put, delete, get,
update, query
hazelcast.objectId
String
the object id to store / find your
object inside the cache (not
needed for the query operation)
Name
Type
Description
CamelHazelcastOperationType
String
valid values are: put, delete,
get, update, query [Version
2.8]
String
the object id to store / find
your object inside the cache
(not needed for the query
operation) [Version 2.8]
CamelHazelcastObjectId
You can call the samples with:
template.sendBodyAndHeader("direct:[put|get|update|delete|query]", "my-foo",
HazelcastConstants.OBJECT_ID, "4711");
Sample for put:
Java DSL:
from("direct:put")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.PUT_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX);
Spring DSL:
put
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Header variables have changed in Camel 2.8
Sample for get:
Java DSL:
from("direct:get")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.GET_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX)
.to("seda:out");
Spring DSL:
get
Sample for update:
Java DSL:
from("direct:update")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.UPDATE_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX);
Spring DSL:
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update
Sample for delete:
Java DSL:
from("direct:delete")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.DELETE_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX);
Spring DSL:
delete
Sample for query
Java DSL:
from("direct:query")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.QUERY_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX)
.to("seda:out");
Spring DSL:
query
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For the query operation Hazelcast offers a SQL like syntax to query your
distributed map.
String q1 = "bar > 1000";
template.sendBodyAndHeader("direct:query", null, HazelcastConstants.QUERY, q1);
map cache consumer - from("hazelcast:map:foo")
Hazelcast provides event listeners on their data grid. If you want to be
notified if a cache will be manipulated, you can use the map consumer.
There're 4 events: put, update, delete and envict. The event type will be
stored in the "hazelcast.listener.action" header variable. The map
consumer provides some additional information inside these variables:
Header Variables inside the response message:
Name
Type
Description
hazelcast.listener.time
Long
time of the event in millis
hazelcast.listener.type
String
the map consumer sets here
"cachelistener"
hazelcast.listener.action
String
type of event - here added,
updated, envicted and
removed
hazelcast.objectId
String
the oid of the object
hazelcast.cache.name
String
the name of the cache - e.g.
"foo"
hazelcast.cache.type
String
the type of the cache - here map
Name
Type
Description
CamelHazelcastListenerTime
Long
time of the event in millis
[Version 2.8]
CamelHazelcastListenerType
String
the map consumer sets here
"cachelistener" [Version
2.8]
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CamelHazelcastListenerAction
String
type of event - here added,
updated, envicted and
removed. [Version 2.8]
CamelHazelcastObjectId
String
the oid of the object
[Version 2.8]
CamelHazelcastCacheName
String
the name of the cache - e.g.
"foo" [Version 2.8]
CamelHazelcastCacheType
String
the type of the cache - here
map [Version 2.8]
The object value will be stored within put and update actions inside the
message body.
Here's a sample:
fromF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX)
.log("object...")
.choice()
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ADDED))
.log("...added")
.to("mock:added")
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ENVICTED))
.log("...envicted")
.to("mock:envicted")
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.UPDATED))
.log("...updated")
.to("mock:updated")
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.REMOVED))
.log("...removed")
.to("mock:removed")
.otherwise()
.log("fail!");
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Usage of Multi Map
multimap cache producer - to("hazelcast:multimap:foo")
A multimap is a cache where you can store n values to one key. The
multimap producer provides 4 operations (put, get, removevalue, delete).
Header Variables for the request message:
Name
Type
Description
hazelcast.operation.type
String
valid values are: put, get,
removevalue, delete
hazelcast.objectId
String
the object id to store / find your
object inside the cache
Name
Type
Description
CamelHazelcastOperationType
String
valid values are: put, delete,
get, update, query Available
as of Camel 2.8
String
the object id to store / find
your object inside the cache
(not needed for the query
operation) [Version 2.8]
CamelHazelcastObjectId
You can call the samples with:
template.sendBodyAndHeader("direct:[put|get|update|delete|query]", "my-foo",
HazelcastConstants.OBJECT_ID, "4711");
Sample for put:
Java DSL:
from("direct:put")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.PUT_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX);
Spring DSL:
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put
Sample for get:
Java DSL:
from("direct:get")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.GET_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX)
.to("seda:out");
Spring DSL:
get
Sample for update:
Java DSL:
from("direct:update")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.UPDATE_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX);
Spring DSL:
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update
Sample for delete:
Java DSL:
from("direct:delete")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.DELETE_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX);
Spring DSL:
delete
Sample for query
Java DSL:
from("direct:query")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.QUERY_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX)
.to("seda:out");
Spring DSL:
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query
For the query operation Hazelcast offers a SQL like syntax to query your
distributed map.
String q1 = "bar > 1000";
template.sendBodyAndHeader("direct:query", null, HazelcastConstants.QUERY, q1);
map cache consumer - from("hazelcast:map:foo")
Hazelcast provides event listeners on their data grid. If you want to be
notified if a cache will be manipulated, you can use the map consumer.
There're 4 events: put, update, delete and envict. The event type will be
stored in the "hazelcast.listener.action" header variable. The map
consumer provides some additional information inside these variables:
Header Variables inside the response message:
667
Name
Type
Description
hazelcast.listener.time
Long
time of the event in millis
hazelcast.listener.type
String
the map consumer sets here
"cachelistener"
hazelcast.listener.action
String
type of event - here added,
updated, envicted and
removed
hazelcast.objectId
String
the oid of the object
hazelcast.cache.name
String
the name of the cache - e.g.
"foo"
hazelcast.cache.type
String
the type of the cache - here map
Name
Type
Description
CamelHazelcastListenerTime
Long
time of the event in millis
[Version 2.8]
CamelHazelcastListenerType
String
the map consumer sets here
"cachelistener" [Version
2.8]
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
Header variables have changed in Camel 2.8
CamelHazelcastListenerAction
String
type of event - here added,
updated, envicted and
removed. [Version 2.8]
CamelHazelcastObjectId
String
the oid of the object
[Version 2.8]
CamelHazelcastCacheName
String
the name of the cache - e.g.
"foo" [Version 2.8]
CamelHazelcastCacheType
String
the type of the cache - here
map [Version 2.8]
The object value will be stored within put and update actions inside the
message body.
Here's a sample:
fromF("hazelcast:%sfoo", HazelcastConstants.MAP_PREFIX)
.log("object...")
.choice()
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ADDED))
.log("...added")
.to("mock:added")
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ENVICTED))
.log("...envicted")
.to("mock:envicted")
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.UPDATED))
.log("...updated")
.to("mock:updated")
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.REMOVED))
.log("...removed")
.to("mock:removed")
.otherwise()
.log("fail!");
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Usage of Multi Map
multimap cache producer - to("hazelcast:multimap:foo")
A multimap is a cache where you can store n values to one key. The
multimap producer provides 4 operations (put, get, removevalue, delete).
Header Variables for the request message:
Name
Type
Description
hazelcast.operation.type
String
valid values are: put, get,
removevalue, delete
hazelcast.objectId
String
the object id to store / find your
object inside the cache
Name
Type
Description
CamelHazelcastOperationType
String
valid values are: put, get,
removevalue, delete [Version
2.8]
CamelHazelcastObjectId
String
the object id to store / find
your object inside the cache
[Version 2.8]
Sample for put:
Java DSL:
from("direct:put")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.PUT_OPERATION))
.to(String.format("hazelcast:%sbar", HazelcastConstants.MULTIMAP_PREFIX));
Spring DSL:
put
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Header variables have changed in Camel 2.8
Sample for removevalue:
Java DSL:
from("direct:removevalue")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.REMOVEVALUE_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.MULTIMAP_PREFIX);
Spring DSL:
removevalue
To remove a value you have to provide the value you want to remove inside
the message body. If you have a multimap object {key: "4711" values: {
"my-foo", "my-bar"}} you have to put "my-foo" inside the message body
to remove the "my-foo" value.
Sample for get:
Java DSL:
from("direct:get")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.GET_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.MULTIMAP_PREFIX)
.to("seda:out");
Spring DSL:
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get
Sample for delete:
Java DSL:
from("direct:delete")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.DELETE_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.MULTIMAP_PREFIX);
Spring DSL:
delete
you can call them in your test class with:
template.sendBodyAndHeader("direct:[put|get|removevalue|delete]", "my-foo",
HazelcastConstants.OBJECT_ID, "4711");
multimap cache consumer from("hazelcast:multimap:foo")
For the multimap cache this component provides the same listeners /
variables as for the map cache consumer (except the update and enviction
listener). The only difference is the multimap prefix inside the URI. Here is a
sample:
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fromF("hazelcast:%sbar", HazelcastConstants.MULTIMAP_PREFIX)
.log("object...")
.choice()
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ADDED))
.log("...added")
.to("mock:added")
//.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ENVICTED))
//
.log("...envicted")
//
.to("mock:envicted")
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.REMOVED))
.log("...removed")
.to("mock:removed")
.otherwise()
.log("fail!");
Header Variables inside the response message:
Name
Type
Description
hazelcast.listener.time
Long
time of the event in millis
hazelcast.listener.type
String
the map consumer sets here
"cachelistener"
hazelcast.listener.action
String
type of event - here added and
removed (and soon envicted)
hazelcast.objectId
String
the oid of the object
hazelcast.cache.name
String
the name of the cache - e.g.
"foo"
hazelcast.cache.type
String
the type of the cache - here
multimap
Eviction will be added as feature, soon (this is a Hazelcast issue).
Name
Type
Description
CamelHazelcastListenerTime
Long
time of the event in millis
[Version 2.8]
CamelHazelcastListenerType
String
the map consumer sets here
"cachelistener" [Version
2.8]
CamelHazelcastListenerAction
String
type of event - here added
and removed (and soon
envicted) [Version 2.8]
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CamelHazelcastObjectId
String
the oid of the object
[Version 2.8]
CamelHazelcastCacheName
String
the name of the cache - e.g.
"foo" [Version 2.8]
CamelHazelcastCacheType
String
the type of the cache - here
multimap [Version 2.8]
Usage of Queue
Queue producer – to(“hazelcast:queue:foo”)
The queue producer provides 6 operations (add, put, poll, peek, offer,
removevalue).
Sample for add:
from("direct:add")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.ADD_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.QUEUE_PREFIX);
Sample for put:
from("direct:put")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.PUT_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.QUEUE_PREFIX);
Sample for poll:
from("direct:poll")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.POLL_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.QUEUE_PREFIX);
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Sample for peek:
from("direct:peek")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.PEEK_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.QUEUE_PREFIX);
Sample for offer:
from("direct:offer")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.OFFER_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.QUEUE_PREFIX);
Sample for removevalue:
from("direct:removevalue")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.REMOVEVALUE_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.QUEUE_PREFIX);
Queue consumer – from(“hazelcast:queue:foo”)
The queue consumer provides 2 operations (add, remove).
fromF("hazelcast:%smm", HazelcastConstants.QUEUE_PREFIX)
.log("object...")
.choice()
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ADDED))
.log("...added")
.to("mock:added")
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.REMOVED))
.log("...removed")
.to("mock:removed")
.otherwise()
.log("fail!");
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Usage of List
List producer – to(“hazelcast:list:foo”)
The list producer provides 4 operations (add, set, get, removevalue).
Sample for add:
from("direct:add")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.ADD_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.LIST_PREFIX);
Sample for get:
from("direct:get")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.GET_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.LIST_PREFIX)
.to("seda:out");
Sample for setvalue:
from("direct:set")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.SETVALUE_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.LIST_PREFIX);
Sample for removevalue:
from("direct:removevalue")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.REMOVEVALUE_OPERATION))
.toF("hazelcast:%sbar", HazelcastConstants.LIST_PREFIX);
List consumer – from(“hazelcast:list:foo”)
The list consumer provides 2 operations (add, remove).
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Please note that set,get and removevalue and not yet supported by
hazelcast, will be added in the future..
fromF("hazelcast:%smm", HazelcastConstants.LIST_PREFIX)
.log("object...")
.choice()
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ADDED))
.log("...added")
.to("mock:added")
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.REMOVED))
.log("...removed")
.to("mock:removed")
.otherwise()
.log("fail!");
Usage of SEDA
SEDA component differs from the rest components provided. It implements a
work-queue in order to support asynchronous SEDA architectures, similar to
the core "SEDA" component.
SEDA producer – to(“hazelcast:seda:foo”)
The SEDA producer provides no operations. You only send data to the
specified queue.
Name
transferExchange
default
value
Description
false
Camel 2.8.0: if set to true the whole
Exchange will be transfered. If header or
body contains not serializable objects, they
will be skipped.
Java DSL :
from("direct:foo")
.to("hazelcast:seda:foo");
Spring DSL :
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SEDA consumer – from(“hazelcast:seda:foo”)
The SEDA consumer provides no operations. You only retrieve data from the
specified queue.
Java DSL :
from("hazelcast:seda:foo")
.to("mock:result");
Spring DSL:
Usage of Atomic Number
atomic number producer to("hazelcast:atomicnumber:foo")
An atomic number is an object that simply provides a grid wide number
(long). The operations for this producer are setvalue (set the number with a
given value), get, increase (+1), decrease (-1) and destroy.
Header Variables for the request message:
Name
Type
Description
hazelcast.operation.type
String
valid values are: setvalue, get,
increase, decrease, destroy
Name
CamelHazelcastOperationType
677
Type
Description
String
valid values are: setvalue, get,
increase, decrease, destroy
Available as of Camel
version 2.8
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There is no consumer for this endpoint!
Header variables have changed in Camel 2.8
Sample for set:
Java DSL:
from("direct:set")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.SETVALUE_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.ATOMICNUMBER_PREFIX);
Spring DSL:
setvalue
Provide the value to set inside the message body (here the value is 10):
template.sendBody("direct:set", 10);
Sample for get:
Java DSL:
from("direct:get")
.setHeader(HazelcastConstants.OPERATION, constant(HazelcastConstants.GET_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.ATOMICNUMBER_PREFIX);
Spring DSL:
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get
You can get the number with long body =
template.requestBody("direct:get", null, Long.class);.
Sample for increment:
Java DSL:
from("direct:increment")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.INCREMENT_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.ATOMICNUMBER_PREFIX);
Spring DSL:
increment
The actual value (after increment) will be provided inside the message body.
Sample for decrement:
Java DSL:
from("direct:decrement")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.DECREMENT_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.ATOMICNUMBER_PREFIX);
Spring DSL:
decrement
The actual value (after decrement) will be provided inside the message body.
Sample for destroy
Java DSL:
from("direct:destroy")
.setHeader(HazelcastConstants.OPERATION,
constant(HazelcastConstants.DESTROY_OPERATION))
.toF("hazelcast:%sfoo", HazelcastConstants.ATOMICNUMBER_PREFIX);
Spring DSL:
destroy
cluster support
instance consumer - from("hazelcast:instance:foo")
Hazelcast makes sense in one single "server node", but it's extremly
powerful in a clustered environment. The instance consumer fires if a new
cache instance will join or leave the cluster.
Here's a sample:
fromF("hazelcast:%sfoo", HazelcastConstants.INSTANCE_PREFIX)
.log("instance...")
.choice()
.when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ADDED))
.log("...added")
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There's a bug inside Hazelcast. So this feature may not work
properly. Will be fixed in 1.9.3.
This endpoint provides no producer!
.to("mock:added")
.otherwise()
.log("...removed")
.to("mock:removed");
Each event provides the following information inside the message header:
Header Variables inside the response message:
681
Name
Type
Description
hazelcast.listener.time
Long
time of the event in millis
hazelcast.listener.type
String
the map consumer sets here
"instancelistener"
hazelcast.listener.action
String
type of event - here added or
removed
hazelcast.instance.host
String
host name of the instance
hazelcast.instance.port
Integer
port number of the instance
Name
Type
Description
CamelHazelcastListenerTime
Long
time of the event in millis
[Version 2.8]
CamelHazelcastListenerType
String
the map consumer sets
here "instancelistener"
[Version 2.8]
CamelHazelcastListenerActionn
String
type of event - here added
or removed. [Version
2.8]
CamelHazelcastInstanceHost
String
host name of the instance
[Version 2.8]
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Header variables have changed in Camel 2.8
CamelHazelcastInstancePort
Integer
port number of the
instance [Version 2.8]
HDFS COMPONENT
Available as of Camel 2.8
The hdfs component enables you to read and write messages from/to an
HDFS file system. HDFS is the distributed file system at the heart of Hadoop.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-hadoopx.x.x
URI format
hdfs://hostname[:port][/path][?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
The path is treated in the following way:
1. as a consumer, if it's a file, it just reads the file, otherwise if it
represents a directory it scans all the file under the path satisfying
the configured pattern. All the files under that directory must be of
the same type.
2. as a producer, if at least one split strategy is defined, the path is
considered a directory and under that directory the producer creates
a different file per split named seg0, seg1, seg2, etc.
Options
Name
Default
Value
Description
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overwrite
true
The file can be overwritten
bufferSize
4096
The buffer size used by HDFS
replication
3
The HDFS replication factor
blockSize
67108864
The size of the HDFS blocks
fileType
NORMAL_FILE
It can be SEQUENCE_FILE, MAP_FILE, ARRAY_FILE, or BLOOMMAP_FILE, see Hadoop
fileSystemType
HDFS
It can be LOCAL for local filesystem
keyType
NULL
The type for the key in case of sequence or map files. See below.
valueType
TEXT
The type for the key in case of sequence or map files. See below.
splitStrategy
A string describing the strategy on how to split the file based on different criteria. See below.
openedSuffix
opened
When a file is opened for reading/writing the file is renamed with this suffix to avoid to read it during
the writing phase.
readSuffix
read
Once the file has been read is renamed with this suffix to avoid to read it again.
initialDelay
0
For the consumer, how much to wait (milliseconds) before to start scanning the directory.
delay
0
The interval (milliseconds) between the directory scans.
pattern
*
The pattern used for scanning the directory
chunkSize
4096
When reading a normal file, this is split into chunks producing a message per chunk.
KeyType and ValueType
• NULL it means that the key or the value is absent
• BYTE for writing a byte, the java Byte class is mapped into a BYTE
• BYTES for writing a sequence of bytes. It maps the java ByteBuffer
class
• INT for writing java integer
• FLOAT for writing java float
• LONG for writing java long
• DOUBLE for writing java double
• TEXT for writing java strings
BYTES is also used with everything else, for example, in Camel a file is sent
around as an InputStream, int this case is written in a sequence file or a map
file as a sequence of bytes.
Splitting Strategy
In the current version of Hadoop opening a file in append mode is disabled
since it's not enough reliable. So, for the moment, it's only possible to create
new files. The Camel HDFS endpoint tries to solve this problem in this way:
• If the split strategy option has been defined, the actual file name will
become a directory name and a /seg0 will be initially
created.
• Every time a splitting condition is met a new file is created with name
/segN where N is 1, 2, 3, etc.
The splitStrategy option is defined as a string with the following
syntax:
splitStrategy=:,:,*
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where can be:
• BYTES a new file is created, and the old is closed when the number of
written bytes is more than
• MESSAGES a new file is created, and the old is closed when the
number of written messages is more than
• IDLE a new file is created, and the old is closed when no writing
happened in the last milliseconds
for example:
hdfs://localhost/tmp/simple-file?splitStrategy=IDLE:1000,BYTES:5
it means: a new file is created either when it has been idle for more than 1
second or if more than 5 bytes have been written. So, running hadoop fs ls /tmp/simple-file you'll find the following files seg0, seg1, seg2, etc
Using this component in OSGi
This component is fully functional in an OSGi environment however, it
requires some actions from the user. Hadoop uses the thread context class
loader in order to load resources. Usually, the thread context classloader will
be the bundle class loader of the bundle that contains the routes. So, the
default configuration files need to be visible from the bundle class loader. A
typical way to deal with it is to keep a copy of core-default.xml in your bundle
root. That file can be found in the hadoop-common.jar.
HIBERNATE COMPONENT
The hibernate: component allows you to work with databases using
Hibernate as the object relational mapping technology to map POJOs to
database tables. The camel-hibernate library is provided by the Camel
Extra project which hosts all *GPL related components for Camel.
Sending to the endpoint
Sending POJOs to the hibernate endpoint inserts entities into the database.
The body of the message is assumed to be an entity bean that you have
mapped to a relational table using the hibernate .hbm.xml files.
If the body does not contain an entity bean, use a Message Translator in
front of the endpoint to perform the necessary conversion first.
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Note that Camel also ships with a JPA component. The JPA
component abstracts from the underlying persistence provider and
allows you to work with Hibernate, OpenJPA or EclipseLink.
Consuming from the endpoint
Consuming messages removes (or updates) entities in the database. This
allows you to use a database table as a logical queue; consumers take
messages from the queue and then delete/update them to logically remove
them from the queue.
If you do not wish to delete the entity when it has been processed, you
can specify consumeDelete=false on the URI. This will result in the entity
being processed each poll.
If you would rather perform some update on the entity to mark it as
processed (such as to exclude it from a future query) then you can annotate
a method with @Consumed which will be invoked on your entity bean when
the entity bean is consumed.
URI format
hibernate:[entityClassName][?options]
For sending to the endpoint, the entityClassName is optional. If specified it
is used to help use the [Type Conversion] to ensure the body is of the correct
type.
For consuming the entityClassName is mandatory.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
685
Name
Default
Value
Description
entityType
entityClassName
Is the provided entityClassName from the URI.
consumeDelete
true
Option for HibernateConsumer only. Specifies whether or not the entity is deleted after it is
consumed.
consumeLockEntity
true
Option for HibernateConsumer only. Specifies whether or not to use exclusive locking of each
entity while processing the results from the pooling.
flushOnSend
true
Option for HibernateProducer only. Flushes the EntityManager after the entity bean has been
persisted.
maximumResults
-1
Option for HibernateConsumer only. Set the maximum number of results to retrieve on the
Query.
consumer.delay
500
Option for HibernateConsumer only. Delay in millis between each poll.
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consumer.initialDelay
1000
Option for HibernateConsumer only. Millis before polling starts.
consumer.userFixedDelay
false
Option for HibernateConsumer only. Set to true to use fixed delay between polls, otherwise
fixed rate is used. See ScheduledExecutorService in JDK for details.
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
HL7 COMPONENT
The hl7 component is used for working with the HL7 MLLP protocol and the
HL7 model using the HAPI library.
This component supports the following:
▪ HL7 MLLP codec for Mina
▪ Agnostic data format using either plain String objects or HAPI HL7
model objects.
▪ Type Converter from/to HAPI and String
▪ HL7 DataFormat using HAPI library
▪ Even more easy-of-use as its integrated well with the camel-mina
component.
Maven users will need to add the following dependency to their pom.xml for
this component:
org.apache.camelcamel-hl7x.x.x
HL7 MLLP protocol
HL7 is often used with the HL7 MLLP protocol that is a text based TCP socket
based protocol. This component ships with a Mina Codec that conforms to
the MLLP protocol so you can easily expose a HL7 listener that accepts HL7
requests over the TCP transport.
To expose a HL7 listener service we reuse the existing camel-mina
component where we just use the HL7MLLPCodec as codec.
The HL7 MLLP codec has the following options:
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Name
Default
Value
Description
startByte
0x0b
The start byte spanning the HL7 payload. Is the HL7 default value of 0x0b (11 decimal).
endByte1
0x1c
The first end byte spanning the HL7 payload. Is the HL7 default value of 0x1c (28 decimal).
endByte2
0x0d
The 2nd end byte spanning the HL7 payload. Is the HL7 default value of 0x0d (13 decimal).
charset
JVM Default
The encoding (is a charset name) to use for the codec. If not provided, Camel will use the JVM default
Charset.
convertLFtoCR
true
Will convert \n to \r (0x0d, 13 decimal) as HL7 usually uses \r as segment terminators. The HAPI
library requires the use of \r.
validate
true
Camel 2.0: Whether HAPI Parser should validate or not.
Exposing a HL7 listener
In our Spring XML file, we configure an endpoint to listen for HL7 requests
using TCP:
Notice we configure it to use camel-mina with TCP on the localhost on port
8888. We use sync=true to indicate that this listener is synchronous and
therefore will return a HL7 response to the caller. Then we setup mina to use
our HL7 codec with codec=#hl7codec. Notice that hl7codec is just a Spring
bean ID, so we could have named it mygreatcodecforhl7 or whatever. The
codec is also set up in the Spring XML file:
And here we configure the charset encoding to use, and iso-8859-1 is
commonly used.
The endpoint hl7listener can then be used in a route as a consumer, as
this java DSL example illustrates:
from("hl7socket").to("patientLookupService");
This is a very simple route that will listen for HL7 and route it to a service
named patientLookupService that is also a Spring bean ID we have
configured in the Spring XML as:
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And another powerful feature of Camel is that we can have our busines logic
in POJO classes that is not at all tied to Camel as shown here:
public class PatientLookupService {
public Message lookupPatient(Message input) throws HL7Exception {
QRD qrd = (QRD)input.get("QRD");
String patientId = qrd.getWhoSubjectFilter(0).getIDNumber().getValue();
// find patient data based on the patient id and create a HL7 model object
with the response
Message response = ... create and set response data
return response
}
Notice that this class is just using imports from the HAPI library and none
from Camel.
HL7 Model using java.lang.String
The HL7MLLP codec uses plain String as data format. And Camel uses Type
Converter to convert from/to strings to the HAPI HL7 model objects. However,
you can use the plain String objects if you prefer, for instance if you need to
parse the data yourself.
See samples for such an example.
HL7 Model using HAPI
The HL7 model is Java objects from the HAPI library. Using this library, we can
encode and decode from the EDI format (ER7) that is mostly used with HL7.
With this model you can code with Java objects instead of the EDI based HL7
format that can be hard for humans to read and understand.
The ER7 sample below is a request to lookup a patient with the patient ID,
0101701234.
MSH|^~\\&|MYSENDER|MYRECEIVER|MYAPPLICATION||200612211200||QRY^A19|1234|P|2.4
QRD|200612211200|R|I|GetPatient|||1^RD|0101701234|DEM||
Using the HL7 model we can work with the data as a
ca.uhn.hl7v2.model.Message.Message object.
To retrieve the patient ID for the patient in the ER7 above, you can do this in
java code:
Message msg = exchange.getIn().getBody(Message.class);
QRD qrd = (QRD)msg.get("QRD");
String patientId = qrd.getWhoSubjectFilter(0).getIDNumber().getValue();
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Camel has built-in type converters, so when this operation is invoked:
Message msg = exchange.getIn().getBody(Message.class);
Camel will convert the received HL7 data from String to Message. This is
powerful when combined with the HL7 listener, then you as the end-user
don't have to work with byte[], String or any other simple object formats.
You can just use the HAPI HL7 model objects.
HL7 DataFormat
The HL7 component ships with a HL7 data format that can be used to format
between String and HL7 model objects.
▪ marshal = from Message to byte stream (can be used when
returning as response using the HL7 MLLP codec)
▪ unmarshal = from byte stream to Message (can be used when
receiving streamed data from the HL7 MLLP
To use the data format, simply instantiate an instance and invoke the
marhsal or unmarshl operation in the route builder:
DataFormat hl7 = new HL7DataFormat();
...
from("direct:hl7in").marshal(hl7).to("jms:queue:hl7out");
In the sample above, the HL7 is marshalled from a HAPI Message object to a
byte stream and put on a JMS queue.
The next example is the opposite:
DataFormat hl7 = new HL7DataFormat();
...
from("jms:queue:hl7out").unmarshal(hl7).to("patientLookupService");
Here we unmarshal the byte stream into a HAPI Message object that is
passed to our patient lookup service.
Notice there is a shorthand syntax in Camel for well-known data formats
that is commonly used.
Then you don't need to create an instance of the HL7DataFormat object:
from("direct:hl7in").marshal().hl7().to("jms:queue:hl7out");
from("jms:queue:hl7out").unmarshal().hl7().to("patientLookupService");
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Message Headers
The unmarshal operation adds these MSH fields as headers on the Camel
message:
Camel 1.x
Key
MSH field
Example
hl7.msh.sendingApplication
MSH-3
MYSERVER
hl7.msh.sendingFacility
MSH-4
MYSERVERAPP
hl7.msh.receivingApplication
MSH-5
MYCLIENT
hl7.msh.receivingFacility
MSH-6
MYCLIENTAPP
hl7.msh.timestamp
MSH-7
20071231235900
hl7.msh.security
MSH-8
null
hl7.msh.messageType
MSH-9-1
ADT
hl7.msh.triggerEvent
MSH-9-2
A01
hl7.msh.messageControl
MSH-10
1234
hl7.msh.processingId
MSH-11
P
hl7.msh.versionId
MSH-12
2.4
Key
MSH field
Example
CamelHL7SendingApplication
MSH-3
MYSERVER
CamelHL7SendingFacility
MSH-4
MYSERVERAPP
CamelHL7ReceivingApplication
MSH-5
MYCLIENT
CamelHL7ReceivingFacility
MSH-6
MYCLIENTAPP
CamelHL7Timestamp
MSH-7
20071231235900
CamelHL7Security
MSH-8
null
CamelHL7MessageType
MSH-9-1
ADT
CamelHL7TriggerEvent
MSH-9-2
A01
CamelHL7MessageControl
MSH-10
1234
CamelHL7ProcessingId
MSH-11
P
CamelHL7VersionId
MSH-12
2.4
Camel 2.0
All headers are String types. If a header value is missing, its value is null.
Options
The HL7 Data Format supports the following options:
Option
Default
Description
validate
true
Camel 2.0: Whether the HAPI Parser should validate.
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Dependencies
To use HL7 in your camel routes you need to add a dependency on camelhl7, which implements this data format.
If you use Maven, you could just add the following to your pom.xml,
substituting the version number for the latest & greatest release (see the
download page for the latest versions).
org.apache.camelcamel-hl72.2.0
Since HAPI 0.6, the library has been split into a base library and several
structures libraries, one for each HL7v2 message version:
• v2.1 structures library
• v2.2 structures library
• v2.3 structures library
• v2.3.1 structures library
• v2.4 structures library
• v2.5 structures library
• v2.5.1 structures library
• v2.6 structures library
By default camel-hl7 only references the HAPI base library. Applications are
responsible for including structures libraries themselves. For example, if a
application works with HL7v2 message versions 2.4 and 2.5 then the
following dependencies must be added:
ca.uhn.hapihapi-structures-v241.0ca.uhn.hapihapi-structures-v251.0
OSGi
An OSGi bundle containing the base library, all structures libraries and
required dependencies (on the bundle classpath) can be downloaded from
the HAPI Maven repository as well.
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ca.uhn.hapihapi-osgi-base1.0.1
Samples
In the following example we send a HL7 request to a HL7 listener and
retrieves a response. We use plain String types in this example:
String line1 =
"MSH|^~\\&|MYSENDER|MYRECEIVER|MYAPPLICATION||200612211200||QRY^A19|1234|P|2.4";
String line2 = "QRD|200612211200|R|I|GetPatient|||1^RD|0101701234|DEM||";
StringBuilder in = new StringBuilder();
in.append(line1);
in.append("\n");
in.append(line2);
String out =
(String)template.requestBody("mina:tcp://127.0.0.1:8888?sync=true&codec=#hl7codec",
in.toString());
In the next sample, we want to route HL7 requests from our HL7 listener to
our business logic. We have our business logic in a plain POJO that we have
registered in the registry as hl7service = for instance using Spring and
letting the bean id = hl7service.
Our business logic is a plain POJO only using the HAPI library so we have
these operations defined:
public class MyHL7BusinessLogic {
// This is a plain POJO that has NO imports whatsoever on Apache Camel.
// its a plain POJO only importing the HAPI library so we can much easier work
with the HL7 format.
public Message handleA19(Message msg) throws Exception {
// here you can have your business logic for A19 messages
assertTrue(msg instanceof QRY_A19);
// just return the same dummy response
return createADR19Message();
}
public Message handleA01(Message msg) throws Exception {
// here you can have your business logic for A01 messages
assertTrue(msg instanceof ADT_A01);
// just return the same dummy response
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return createADT01Message();
}
}
Then we set up the Camel routes using the RouteBuilder as follows:
DataFormat hl7 = new HL7DataFormat();
// we setup or HL7 listener on port 8888 (using the hl7codec) and in sync mode so we
can return a response
from("mina:tcp://127.0.0.1:8888?sync=true&codec=#hl7codec")
// we use the HL7 data format to unmarshal from HL7 stream to the HAPI Message
model
// this ensures that the camel message has been enriched with hl7 specific
headers to
// make the routing much easier (see below)
.unmarshal(hl7)
// using choice as the content base router
.choice()
// where we choose that A19 queries invoke the handleA19 method on our
hl7service bean
.when(header("CamelHL7TriggerEvent").isEqualTo("A19"))
.beanRef("hl7service", "handleA19")
.to("mock:a19")
// and A01 should invoke the handleA01 method on our hl7service bean
.when(header("CamelHL7TriggerEvent").isEqualTo("A01")).to("mock:a01")
.beanRef("hl7service", "handleA01")
.to("mock:a19")
// other types should go to mock:unknown
.otherwise()
.to("mock:unknown")
// end choice block
.end()
// marhsal response back
.marshal(hl7);
Notice that we use the HL7 DataFormat to enrich our Camel Message with
the MSH fields preconfigued on the Camel Message. This lets us much more
easily define our routes using the fluent builders.
If we do not use the HL7 DataFormat, then we do not gains these headers
and we must resort to a different technique for computing the MSH trigger
event (= what kind of HL7 message it is). This is a big advantage of the HL7
DataFormat over the plain HL7 type converters.
Sample using plain String objects
In this sample we use plain String objects as the data format, that we send,
process and receive. As the sample is part of a unit test, there is some code
for assertions, but you should be able to understand what happens. First we
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send the plain string, Hello World, to the HL7MLLPCodec and receive the
response as a plain string, Bye World.
MockEndpoint mock = getMockEndpoint("mock:result");
mock.expectedBodiesReceived("Bye World");
// send plain hello world as String
Object out =
template.requestBody("mina:tcp://127.0.0.1:8888?sync=true&codec=#hl7codec", "Hello
World");
assertMockEndpointsSatisfied();
// and the response is also just plain String
assertEquals("Bye World", out);
Here we process the incoming data as plain String and send the response
also as plain String:
from("mina:tcp://127.0.0.1:8888?sync=true&codec=#hl7codec")
.process(new Processor() {
public void process(Exchange exchange) throws Exception {
// use plain String as message format
String body = exchange.getIn().getBody(String.class);
assertEquals("Hello World", body);
// return the response as plain string
exchange.getOut().setBody("Bye World");
}
})
.to("mock:result");
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
HTTP COMPONENT
The http: component provides HTTP based endpoints for consuming external
HTTP resources (as a client to call external servers using HTTP).
Maven users will need to add the following dependency to their pom.xml
for this component:
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org.apache.camelcamel-httpx.x.x
URI format
http:hostname[:port][/resourceUri][?options]
Will by default use port 80 for HTTP and 443 for HTTPS.
You can append query options to the URI in the following format,
?option=value&option=value&...
HttpEndpoint Options
Name
Default
Value
Description
throwExceptionOnFailure
true
Camel 2.0: Option to disable throwing the HttpOperationFailedException in case of failed
responses from the remote server. This allows you to get all responses regardles of the HTTP
status code.
bridgeEndpoint
false
Camel 2.1: If the option is true , HttpProducer will ignore the Exchange.HTTP_URI header, and
use the endpoint's URI for request. You may also set the throwExcpetionOnFailure to be false
to let the HttpProducer send all the fault response back.
Camel 2.3: If the option is true, HttpProducer and CamelServlet will skip the gzip processing if
the content-encoding is "gzip".
disableStreamCache
false
Camel 2.3: DefaultHttpBinding will copy the request input stream into a stream cache and put it
into message body if this option is false to support read it twice, otherwise DefaultHttpBinding
will set the request input stream direct into the message body.
httpBindingRef
null
Reference to a org.apache.camel.component.http.HttpBinding in the Registry. From Camel
2.3 onwards prefer to use the httpBinding option.
httpBinding
null
Camel 2.3: Reference to a org.apache.camel.component.http.HttpBinding in the Registry.
httpClientConfigurerRef
null
Reference to a org.apache.camel.component.http.HttpClientConfigurer in the Registry.
From Camel 2.3 onwards prefer to use the httpClientConfigurer option.
httpClientConfigurer
null
Camel 2.3: Reference to a org.apache.camel.component.http.HttpClientConfigurer in the
Registry.
httpClient.XXX
null
Setting options on the HttpClientParams. For instance httpClient.soTimeout=5000 will set the
SO_TIMEOUT to 5 seconds.
clientConnectionManager
null
Camel 2.3: To use a custom org.apache.http.conn.ClientConnectionManager.
transferException
false
Camel 2.6: If enabled and an Exchange failed processing on the consumer side, and if the
caused Exception was send back serialized in the response as a application/x-javaserialized-object content type (for example using Jetty or SERVLET Camel components). On
the producer side the exception will be deserialized and thrown as is, instead of the
HttpOperationFailedException. The caused exception is required to be serialized.
The following authentication options can also be set on the HttpEndpoint:
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camel-http vs camel-jetty
You can only produce to endpoints generated by the HTTP
component. Therefore it should never be used as input into your
camel Routes. To bind/expose an HTTP endpoint via a HTTP server
as input to a camel route, you can use the Jetty Component
Camel 2.2 or older: Setting Authentication and Proxy
Name
Default
Value
Description
username
null
Username for authentication.
password
null
Password for authentication.
domain
null
Camel 2.1: Domain for NTML Authentication. This option must be used to force NTML
authentication.
proxyHost
null
Camel 1.6.2: The proxy host name
proxyPort
null
Camel 1.6.2: The proxy port number
proxyUsername
null
Camel 1.6.2: Username for proxy authentication
proxyPassword
null
Camel 1.6.2: Password for proxy authentication
Camel 2.3 or newer: HttpConfiguration - Setting
Authentication and Proxy
Name
Default
Value
Description
authMethod
null
Authentication method, either as Basic, Digest or NTLM.
authMethodPriority
null
Priority of authentication methods. Is a list separated with comma. For example: Basic,Digest
to exclude NTLM.
authUsername
null
Username for authentication
authPassword
null
Password for authentication
authDomain
null
Domain for NTML authentication
authHost
null
Optional host for NTML authentication
proxyHost
null
The proxy host name
proxyPort
null
The proxy port number
proxyAuthMethod
null
Authentication method for proxy, either as Basic, Digest or NTLM.
proxyAuthUsername
null
Username for proxy authentication
proxyAuthPassword
null
Password for proxy authentication
proxyAuthDomain
null
Domain for proxy NTML authentication
proxyAuthHost
null
Optional host for proxy NTML authentication
When using authentication you must provide the choice of method for the
authMethod or authProxyMethod options.
You can configure the proxy and authentication details on either the
HttpComponent or the HttpEndoint. Values provided on the HttpEndpoint
will take precedence over HttpComponent. Its most likely best to configure
this on the HttpComponent which allows you to do this once.
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The HTTP component uses convention over configuration which means
that if you have not explicit set a authMethodPriority then it will fallback
and use the select(ed) authMethod as priority as well. So if you use
authMethod.Basic then the auhtMethodPriority will be Basic only.
HttpComponent Options
Name
Default Value
Description
httpBinding
null
To use a custom org.apache.camel.component.http.HttpBinding.
httpClientConfigurer
null
To use a custom org.apache.camel.component.http.HttpClientConfigurer.
httpConnectionManager
null
To use a custom org.apache.commons.httpclient.HttpConnectionManager.
httpConfiguration
null
Camel 2.3: To use a custom org.apache.camel.component.http.HttpConfiguration
HttpConfiguration contains all the options listed in the table above under
the section HttpConfiguration - Setting Authentication and Proxy.
Message Headers
Camel 1.x
Name
Type
Description
HttpProducer.HTTP_URI
String
Camel 1.6.0: URI to call. Will override existing URI set directly on the endpoint. Is set on the
In message.
HttpProducer.HTTP_RESPONSE_CODE
int
The HTTP response code from the external server. Is 200 for OK. Is set on the Out message.
HttpProducer.QUERY
String
URI parameters. Will override existing URI parameters set directly on the endpoint. Is set on
the In message.
Camel 2.x
697
Name
Type
Description
Exchange.HTTP_URI
String
URI to call. Will override existing URI set directly on the endpoint.
Exchange.HTTP_PATH
String
Request URI's path, the header will be used to build the request URI with the
HTTP_URI. Camel 2.3.0: If the path is start with "/", http producer will try to
find the relative path based on the Exchange.HTTP_BASE_URI header or the
exchange.getFromEndpoint().getEndpointUri();
Exchange.HTTP_QUERY
String
URI parameters. Will override existing URI parameters set directly on the
endpoint.
Exchange.HTTP_RESPONSE_CODE
int
The HTTP response code from the external server. Is 200 for OK.
Exchange.HTTP_CHARACTER_ENCODING
String
Character encoding.
Exchange.CONTENT_TYPE
String
The HTTP content type. Is set on both the IN and OUT message to provide a
content type, such as text/html.
Exchange.CONTENT_ENCODING
String
The HTTP content encoding. Is set on both the IN and OUT message to provide
a content encoding, such as gzip.
Exchange.HTTP_SERVLET_REQUEST
HttpServletRequest
Camel 2.3: The HttpServletRequest object.
Exchange.HTTP_SERVLET_RESPONSE
HttpServletResponse
Camel 2.3: The HttpServletResponse object.
Exchange.HTTP_PROTOCOL_VERSION
String
Camel 2.5: You can set the http protocol version with this header, eg. "HTTP/
1.0". If you didn't specify the header, HttpProducer will use the default value
"HTTP/1.1"
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Message Body
Camel will store the HTTP response from the external server on the OUT
body. All headers from the IN message will be copied to the OUT message, so
headers are preserved during routing. Additionally Camel will add the HTTP
response headers as well to the OUT message headers.
Response code
Camel will handle according to the HTTP response code:
▪ Response code is in the range 100..299, Camel regards it as a
success response.
▪ Response code is in the range 300..399, Camel regards it as a
redirection response and will throw a
HttpOperationFailedException with the information.
▪ Response code is 400+, Camel regards it as an external server failure
and will throw a HttpOperationFailedException with the
information.
HttpOperationFailedException
This exception contains the following information:
▪ The HTTP status code
▪ The HTTP status line (text of the status code)
▪ Redirect location, if server returned a redirect
▪ Response body as a java.lang.String, if server provided a body as
response
Calling using GET or POST
In Camel 1.5 the following algorithm is used to determine if either GET or
POST HTTP method should be used:
1. Use method provided in header.
2. GET if query string is provided in header.
3. GET if endpoint is configured with a query string.
4. POST if there is data to send (body is not null).
5. GET otherwise.
How to get access to HttpServletRequest and HttpServletResponse
Available as of Camel 2.0
You can get access to these two using the Camel type converter system
using
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throwExceptionOnFailure
The option, throwExceptionOnFailure, can be set to false to
prevent the HttpOperationFailedException from being thrown for
failed response codes. This allows you to get any response from the
remote server.
There is a sample below demonstrating this.
NOTE from Camel 2.3.0 you can get the request and response not just from
the processor after the camel-jetty or camel-cxf endpoint.
HttpServletRequest request = exchange.getIn().getBody(HttpServletRequest.class);
HttpServletRequest response = exchange.getIn().getBody(HttpServletResponse.class);
Configuring URI to call
You can set the HTTP producer's URI directly form the endpoint URI. In the
route below, Camel will call out to the external server, oldhost, using HTTP.
from("direct:start")
.to("http://oldhost");
And the equivalent Spring sample:
In Camel 1.5.1 you can override the HTTP endpoint URI by adding a header
with the key, HttpProducer.HTTP_URI, on the message.
from("direct:start")
.setHeader(org.apache.camel.component.http.HttpProducer.HTTP_URI,
constant("http://newhost"))
.to("http://oldhost");
In the sample above Camel will call the http://newhost despite the endpoint
is configured with http://oldhost.
And the same code in Camel 2.0:
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from("direct:start")
.setHeader(HttpConstants.HTTP_URI, constant("http://newhost"))
.to("http://oldhost");
Where Constants is the class,
org.apache.camel.component.http.Constants.
Configuring URI Parameters
Camel 1.x
The http producer supports URI parameters to be sent to the HTTP server.
The URI parameters can either be set directly on the endpoint URI or as a
header with the key HttpProducer.QUERY on the message.
from("direct:start")
.to("http://oldhost?order=123&detail=short");
Or options provided in a header:
from("direct:start")
.setHeader(HttpConstants.HTTP_QUERY, constant("order=123&detail=short"))
.to("http://oldhost");
Camel 2.x
The http producer supports URI parameters to be sent to the HTTP server.
The URI parameters can either be set directly on the endpoint URI or as a
header with the key Exchange.HTTP_QUERY on the message.
from("direct:start")
.to("http://oldhost?order=123&detail=short");
Or options provided in a header:
from("direct:start")
.setHeader(Exchange.HTTP_QUERY, constant("order=123&detail=short"))
.to("http://oldhost");
How to set the http method (GET/POST/PUT/DELETE/HEAD/OPTIONS/
TRACE) to the HTTP producer
The HTTP component provides a way to set the HTTP request method by
setting the message header. Here is an example;
Camel 1.x
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from("direct:start")
.setHeader(HttpConstants.HTTP_METHOD,
constant(org.apache.camel.component.http.HttpMethods.POST))
.to("http://www.google.com")
.to("mock:results");
Camel 2.x
from("direct:start")
.setHeader(Exchange.HTTP_METHOD,
constant(org.apache.camel.component.http.HttpMethods.POST))
.to("http://www.google.com")
.to("mock:results");
The method can be written a bit shorter using the string constants:
.setHeader("CamelHttpMethod", constant("POST"))
And the equivalent Spring sample:
POST
Using client tineout - SO_TIMEOUT
See the unit test in this link
Configuring a Proxy
Only for >= Camel 1.6.2
The HTTP component provides a way to configure a proxy.
from("direct:start")
.to("http://oldhost?proxyHost=www.myproxy.com&proxyPort=80");
There is also support for proxy authentication via the proxyUsername and
proxyPassword options.
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Using proxy settings outside of URI
*Only for >= Camel 1.6.2 and < Camel 2.2.0 *
The HTTP component will detect Java System Properties for http.proxyHost
and http.proxyPort and use them if provided.
See more at SUN http proxy documentation.
To avoid the System properties conflicts, from Camel 2.2.0 you can only
set the proxy configure from CameContext or URI.
Java DSL :
context.getProperties().put("http.proxyHost", "172.168.18.9");
context.getProperties().put("http.proxyPort" "8080");
Spring XML
Camel will first set the settings from Java System or CamelContext Properties
and then the endpoint proxy options if provided.
So you can override the system properties with the endpoint options.
Configuring charset
If you are using POST to send data you can configure the charset using the
Exchange property:
exchange.setProperty(Exchange.CHARSET_NAME, "iso-8859-1");
Sample with scheduled poll
The sample polls the Google homepage every 10 seconds and write the page
to the file message.html:
from("timer://foo?fixedRate=true&delay=0&period=10000")
.to("http://www.google.com")
.setHeader(FileComponent.HEADER_FILE_NAME, "message.html").to("file:target/
google");
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URI Parameters from the endpoint URI
In this sample we have the complete URI endpoint that is just what you
would have typed in a web browser. Multiple URI parameters can of course
be set using the & character as separator, just as you would in the web
browser. Camel does no tricks here.
// we query for Camel at the Google page
template.sendBody("http://www.google.com/search?q=Camel", null);
URI Parameters from the Message
Map headers = new HashMap();
headers.put(HttpProducer.QUERY, "q=Camel&lr=lang_en");
// we query for Camel and English language at Google
template.sendBody("http://www.google.com/search", null, headers);
In the header value above notice that it should not be prefixed with ? and
you can separate parameters as usual with the & char.
Getting the Response Code
You can get the HTTP response code from the HTTP component by getting
the value from the Out message header with
HttpProducer.HTTP_RESPONSE_CODE.
Exchange exchange = template.send("http://www.google.com/search", new Processor() {
public void process(Exchange exchange) throws Exception {
exchange.getIn().setHeader(HttpProducer.QUERY,
constant("hl=en&q=activemq"));
}
});
Message out = exchange.getOut();
int responseCode = out.getHeader(HttpProducer.HTTP_RESPONSE_CODE, Integer.class);
Using throwExceptionOnFailure=false to get any response back
Available as of Camel 2.0
In the route below we want to route a message that we enrich with data
returned from a remote HTTP call. As we want any response from the remote
server, we set the throwExceptionOnFailure option to false so we get any
response in the AggregationStrategy. As the code is based on a unit test
that simulates a HTTP status code 404, there is some assertion code etc.
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// We set throwExceptionOnFailure to false to let Camel return any response from the
remove HTTP server without thrown
// HttpOperationFailedException in case of failures.
// This allows us to handle all responses in the aggregation strategy where we can
check the HTTP response code
// and decide what to do. As this is based on an unit test we assert the code is 404
from("direct:start").enrich("http://localhost:{{port}}/
myserver?throwExceptionOnFailure=false&user=Camel", new AggregationStrategy() {
public Exchange aggregate(Exchange original, Exchange resource) {
// get the response code
Integer code = resource.getIn().getHeader(Exchange.HTTP_RESPONSE_CODE,
Integer.class);
assertEquals(404, code.intValue());
return resource;
}
}).to("mock:result");
// this is our jetty server where we simulate the 404
from("jetty://http://localhost:{{port}}/myserver")
.process(new Processor() {
public void process(Exchange exchange) throws Exception {
exchange.getOut().setBody("Page not found");
exchange.getOut().setHeader(Exchange.HTTP_RESPONSE_CODE, 404);
}
});
Disabling Cookies
To disable cookies you can set the HTTP Client to ignore cookies by adding
this URI option:
httpClient.cookiePolicy=ignoreCookies
Advanced Usage
If you need more control over the HTTP producer you should use the
HttpComponent where you can set various classes to give you custom
behavior.
Setting MaxConnectionsPerHost
The HTTP Component has a
org.apache.commons.httpclient.HttpConnectionManager where you can
configure various global configuration for the given component.
By global, we mean that any endpoint the component creates has the same
shared HttpConnectionManager. So, if we want to set a different value for
the max connection per host, we need to define it on the HTTP component
and not on the endpoint URI that we usually use. So here comes:
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First, we define the http component in Spring XML. Yes, we use the same
scheme name, http, because otherwise Camel will auto-discover and create
the component with default settings. What we need is to overrule this so we
can set our options. In the sample below we set the max connection to 5
instead of the default of 2.
And then we can just use it as we normally do in our routes:
Using HTTPS to authenticate gotchas
An end user reported that he had problem with authenticating with HTTPS.
The problem was eventually resolved when he discovered the HTTPS server
did not return a HTTP code 401 Authorization Required. The solution was to
set the following URI option: httpClient.authenticationPreemptive=true
Accepting self signed certifications from remote server
See this link from a mailing list discussion with some code to outline how to
do this with the Apache Commons HTTP API.
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Setting up SSL for HTTP Client
Using the JSSE Configuration Utility
As of Camel 2.8, the HTTP4 component supports SSL/TLS configuration
through the Camel JSSE Configuration Utility. This utility greatly decreases
the amount of component specific code you need to write and is configurable
at the endpoint and component levels. The following examples demonstrate
how to use the utility with the HTTP4 component.
The version of the Apache HTTP client used in this component resolves
SSL/TLS information from a global "protocol" registry. This component
provides an implementation,
org.apache.camel.component.http.SSLContextParametersSecureProtocolSocketFac
of the HTTP client's protocol socket factory in order to support the use of the
Camel JSSE Configuration utility. The following example demonstrates how to
configure the protocol registry and use the registered protocol information in
a route.
KeyStoreParameters ksp = new KeyStoreParameters();
ksp.setResource("/users/home/server/keystore.jks");
ksp.setPassword("keystorePassword");
KeyManagersParameters kmp = new KeyManagersParameters();
kmp.setKeyStore(ksp);
kmp.setKeyPassword("keyPassword");
SSLContextParameters scp = new SSLContextParameters();
scp.setKeyManagers(kmp);
ProtocolSocketFactory factory =
new SSLContextParametersSecureProtocolSocketFactory(scp);
Protocol.registerProtocol("https",
new Protocol(
"https",
factory,
443));
from("direct:start")
.to("https://mail.google.com/mail/").to("mock:results");
Configuring Apache HTTP Client Directly
Basically camel-http component is built on the top of Apache HTTP client,
and you can implement a custom
org.apache.camel.component.http.HttpClientConfigurer to do some
configuration on the http client if you need full control of it.
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However if you just want to specify the keystore and truststore you can do
this with Apache HTTP HttpClientConfigurer, for example:
Protocol authhttps = new Protocol("https", new AuthSSLProtocolSocketFactory(
new URL("file:my.keystore"), "mypassword",
new URL("file:my.truststore"), "mypassword"), 443);
Protocol.registerProtocol("https", authhttps);
And then you need to create a class that implements
HttpClientConfigurer, and registers https protocol providing a keystore or
truststore per example above. Then, from your camel route builder class you
can hook it up like so:
HttpComponent httpComponent = getContext().getComponent("http", HttpComponent.class);
httpComponent.setHttpClientConfigurer(new MyHttpClientConfigurer());
If you are doing this using the Spring DSL, you can specify your
HttpClientConfigurer using the URI. For example:
As long as you implement the HttpClientConfigurer and configure your
keystore and truststore as described above, it will work fine.
See Also
•
•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
Jetty
IBATIS
The ibatis: component allows you to query, poll, insert, update and delete
data in a relational database using Apache iBATIS.
Maven users will need to add the following dependency to their pom.xml
for this component:
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org.apache.camelcamel-ibatisx.x.x
URI format
ibatis:statementName[?options]
Where statementName is the name in the iBATIS XML configuration file
which maps to the query, insert, update or delete operation you wish to
evaluate.
You can append query options to the URI in the following format,
?option=value&option=value&...
This component will by default load the iBatis SqlMapConfig file from the
root of the classpath and expected named as SqlMapConfig.xml.
It uses Spring resource loading so you can define it using classpath, file or
http as prefix to load resources with those schemes.
In Camel 2.2 you can configure this on the iBatisComponent with the
setSqlMapConfig(String) method.
Options
Option
Type
Default
Description
consumer.onConsume
String
null
Statements to run after consuming. Can be used, for
example, to update rows after they have been
consumed and processed in Camel. See sample later.
Multiple statements can be separated with comma.
consumer.useIterator
boolean
true
If true each row returned when polling will be
processed individually. If false the entire List of data
is set as the IN body.
consumer.routeEmptyResultSet
boolean
false
Camel 2.0: Sets whether empty result set should be
routed or not. By default, empty result sets are not
routed.
statementType
StatementType
null
Camel 1.6.1/2.0: Mandatory to specify for
IbatisProducer to control which iBatis SqlMapClient
method to invoke. The enum values are:
QueryForObject, QueryForList, Insert, Update,
Delete.
maxMessagesPerPoll
int
0
Camel 2.0: An integer to define a maximum messages
to gather per poll. By default, no maximum is set. Can
be used to set a limit of e.g. 1000 to avoid when
starting up the server that there are thousands of files.
Set a value of 0 or negative to disabled it.
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isolation
isolation
String
String
TRANSACTION_REPEATABLE_READ
TRANSACTION_REPEATABLE_READ
Camel 2.9: A String the defines the transaction
isolation level of the will be used. Allowed values are
TRANSACTION_NONE,
TRANSACTION_READ_UNCOMMITTED,
TRANSACTION_READ_COMMITTED,
TRANSACTION_REPEATABLE_READ,
TRANSACTION_SERIALIZABLE
Camel 2.9: A String the defines the transaction isolation level of the will be used.
Allowed values are TRANSACTION_NONE, TRANSACTION_READ_UNCOMMITTED,
TRANSACTION_READ_COMMITTED, TRANSACTION_REPEATABLE_READ,
TRANSACTION_SERIALIZABLE
Message Headers
Camel will populate the result message, either IN or OUT with a header with
the operationName used:
Header
Type
Description
org.apache.camel.ibatis.queryName
String
Camel 1.x: The statementName used (for example: insertAccount).
CamelIBatisStatementName
String
Camel 2.0: The statementName used (for example: insertAccount).
CamelIBatisResult
Object
Camel 1.6.2/2.0: The response returned from iBatis in any of the operations. For instance
an INSERT could return the auto-generated key, or number of rows etc.
Message Body
Camel 1.6.1: The response from iBatis will be set as OUT body
Camel 1.6.2/2.0: The response from iBatis will only be set as body if it's a
SELECT statement. That means, for example, for INSERT statements Camel
will not replace the body. This allows you to continue routing and keep the
original body. The response from iBatis is always stored in the header with
the key CamelIBatisResult.
Samples
For example if you wish to consume beans from a JMS queue and insert them
into a database you could do the following:
from("activemq:queue:newAccount").
to("ibatis:insertAccount?statementType=Insert");
Notice we have to specify the statementType, as we need to instruct Camel
which SqlMapClient operation to invoke.
Where insertAccount is the iBatis ID in the SQL map file:
insert into ACCOUNT (
ACC_ID,
ACC_FIRST_NAME,
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ACC_LAST_NAME,
ACC_EMAIL
)
values (
#id#, #firstName#, #lastName#, #emailAddress#
)
Using StatementType for better control of IBatis
Available as of Camel 1.6.1/2.0
When routing to an iBatis endpoint you want more fine grained control so you
can control whether the SQL statement to be executed is a SELEECT, UPDATE,
DELETE or INSERT etc. This is now possible in Camel 1.6.1/2.0. So for instance
if we want to route to an iBatis endpoint in which the IN body contains
parameters to a SELECT statement we can do:
from("direct:start")
.to("ibatis:selectAccountById?statementType=QueryForObject")
.to("mock:result");
In the code above we can invoke the iBatis statement selectAccountById
and the IN body should contain the account id we want to retrieve, such as
an Integer type.
We can do the same for some of the other operations, such as
QueryForList:
from("direct:start")
.to("ibatis:selectAllAccounts?statementType=QueryForList")
.to("mock:result");
And the same for UPDATE, where we can send an Account object as IN body
to iBatis:
from("direct:start")
.to("ibatis:updateAccount?statementType=Update")
.to("mock:result");
Scheduled polling example
Since this component does not support scheduled polling, you need to use
another mechanism for triggering the scheduled polls, such as the Timer or
Quartz components.
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In the sample below we poll the database, every 30 seconds using the
Timer component and send the data to the JMS queue:
from("timer://pollTheDatabase?delay=30000").to("ibatis:selectAllAccounts?statementType=QueryForList").
And the iBatis SQL map file used:
Using onConsume
This component supports executing statements after data have been
consumed and processed by Camel. This allows you to do post updates in the
database. Notice all statements must be UPDATE statements. Camel supports
executing multiple statements whose name should be separated by comma.
The route below illustrates we execute the consumeAccount statement
data is processed. This allows us to change the status of the row in the
database to processed, so we avoid consuming it twice or more.
from("ibatis:selectUnprocessedAccounts?consumer.onConsume=consumeAccount").to("mock:results");
And the statements in the sqlmap file:
update ACCOUNT set PROCESSED = true where ACC_ID = #id#
See Also
•
•
•
•
711
Configuring Camel
Component
Endpoint
Getting Started
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
IRC COMPONENT
The irc component implements an IRC (Internet Relay Chat) transport.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-ircx.x.x
URI format
irc:nick@host[:port]/#room[?options]
In Camel 2.0, you can also use the following format:
irc:nick@host[:port]?channels=#channel1,#channel2,#channel3[?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Description
Example
Default
Value
channels
Camel 2.0: Comma separated list of IRC channels to
join.
channels=#channel1,#channel2
null
nickname
The nickname used in chat.
irc:MyNick@irc.server.org#channel or
irc:irc.server.org#channel?nickname=MyUser
null
username
The IRC server user name.
irc:MyUser@irc.server.org#channel or
irc:irc.server.org#channel?username=MyUser
Same as
nickname.
password
The IRC server password.
password=somepass
None
realname
The IRC user's actual name.
realname=MyName
None
colors
Whether or not the server supports color codes.
true, false
true
onReply
Whether or not to handle general responses to
commands or informational messages.
true, false
false
onNick
Handle nickname change events.
true, false
true
onQuit
Handle user quit events.
true, false
true
onJoin
Handle user join events.
true, false
true
onKick
Handle kick events.
true, false
true
onMode
Handle mode change events.
true, false
true
onPart
Handle user part events.
true, false
true
onTopic
Handle topic change events.
true, false
true
onPrivmsg
Handle message events.
true, false
true
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trustManager
Camel 2.0: The trust manager used to verify the SSL
server's certificate.
trustManager=#referenceToTrustManagerBean
The default trust
manager, which
accepts all
certificates, will
be used.
keys
Camel 2.2: Comma separated list of IRC channel
keys. Important to be listed in same order as channels.
When joining multiple channels with only some
needing keys just insert an empty value for that
channel.
irc:MyNick@irc.server.org/
#channel?keys=chankey
null
SSL Support
As of Camel 2.0, you can also connect to an SSL enabled IRC server, as
follows:
ircs:host[:port]/#room?username=user&password=pass
By default, the IRC transport uses SSLDefaultTrustManager. If you need to
provide your own custom trust manager, use the trustManager parameter
as follows:
ircs:host[:port]/
#room?username=user&password=pass&trustManager=#referenceToMyTrustManagerBean
Using keys
Available as of Camel 2.2
Some irc rooms requires you to provide a key to be able to join that
channel. The key is just a secret word.
For example we join 3 channels where as only channel 1 and 3 uses a key.
irc:nick@irc.server.org?channels=#chan1,#chan2,#chan3&keys=chan1Key,,chan3key
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
JASYPT COMPONENT
Available as of Camel 2.5
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Jasypt is a simplified encryption library which makes encryption and
decryption easy. Camel integrates with Jasypt to allow sensitive information
in Properties files to be encrypted. By dropping camel-jasypt on the
classpath those encrypted values will automatic be decrypted on-the-fly by
Camel. This ensures that human eyes can't easily spot sensitive information
such as usernames and passwords.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-jasyptx.x.x
Tooling
The Jasypt component provides a little command line tooling to encrypt or
decrypt values.
The console output the syntax and which options it provides:
Apache Camel Jasypt takes the following options
-h
-c
-p
-i
-a
or
or
or
or
or
-help = Displays the help screen
-command = Command either encrypt or decrypt
-password = Password to use
-input = Text to encrypt or decrypt
-algorithm = Optional algorithm to use
For example to encrypt the value tiger you run with the following
parameters. In the apache camel kit, you cd into the lib folder and run the
following java cmd, where is where you have downloaded
and extract the Camel distribution.
$ cd /lib
$ java -jar camel-jasypt-2.5.0.jar -c encrypt -p secret -i tiger
Which outputs the following result
Encrypted text: qaEEacuW7BUti8LcMgyjKw==
This means the encrypted representation qaEEacuW7BUti8LcMgyjKw== can
be decrypted back to tiger if you know the master password which was
secret.
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If you run the tool again then the encrypted value will return a different
result. But decrypting the value will always return the correct original value.
So you can test it by running the tooling using the following parameters:
$ cd /lib
$ java -jar camel-jasypt-2.5.0.jar -c decrypt -p secret -i qaEEacuW7BUti8LcMgyjKw==
Which outputs the following result:
Decrypted text: tiger
The idea is then to use those encrypted values in your Properties files. Notice
how the password value is encrypted and the value has the tokens
surrounding ENC(value here)
# refer to a mock endpoint name by that encrypted password
cool.result=mock:{{cool.password}}
# here is a password which is encrypted
cool.password=ENC(bsW9uV37gQ0QHFu7KO03Ww==)
Tooling dependencies for Camel 2.5 and 2.6
The tooling requires the following JARs in the classpath, which has been
enlisted in the MANIFEST.MF file of camel-jasypt with optional/ as prefix.
Hence why the java cmd above can pickup the needed JARs from the Apache
Distribution in the optional directory.
jasypt-1.6.jar commons-lang-2.4.jar commons-codec-1.4.jar icu4j-4.0.1.jar
Tooling dependencies for Camel 2.7 or better
Jasypt 1.7 onwards is now fully standalone so no additional JARs is needed.
URI Options
The options below are exclusive for the Jasypt component.
715
Name
Default
Value
Type
Description
password
null
String
Specifies the master password to use for decrypting. This option is mandatory. See below for
more details.
algorithm
null
String
Name of an optional algorithm to use.
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Java 1.5 users
The icu4j-4.0.1.jar is only needed when running on JDK 1.5.
This JAR is not distributed by Apache Camel and you have to download it
manually and copy it to the lib/optional directory of the Camel
distribution.
You can download it from Apache Central Maven repo.
Protecting the master password
The master password used by Jasypt must be provided, so its capable of
decrypting the values. However having this master password out in the
opening may not be an ideal solution. Therefore you could for example
provided it as a JVM system property or as a OS environment setting. If you
decide to do so then the password option supports prefixes which dictates
this. sysenv: means to lookup the OS system environment with the given
key. sys: means to lookup a JVM system property.
For example you could provided the password before you start the
application
$ export CAMEL_ENCRYPTION_PASSWORD=secret
Then start the application, such as running the start script.
When the application is up and running you can unset the environment
$ unset CAMEL_ENCRYPTION_PASSWORD
The password option is then a matter of defining as follows:
password=sysenv:CAMEL_ENCRYPTION_PASSWORD.
Example with Java DSL
In Java DSL you need to configure Jasypt as a JasyptPropertiesParser
instance and set it on the Properties component as show below:
// create the jasypt properties parser
JasyptPropertiesParser jasypt = new JasyptPropertiesParser();
// and set the master password
jasypt.setPassword("secret");
// create the properties component
PropertiesComponent pc = new PropertiesComponent();
pc.setLocation("classpath:org/apache/camel/component/jasypt/myproperties.properties");
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// and use the jasypt properties parser so we can decrypt values
pc.setPropertiesParser(jasypt);
// add properties component to camel context
context.addComponent("properties", pc);
The properties file myproperties.properties then contain the encrypted
value, such as shown below. Notice how the password value is encrypted and
the value has the tokens surrounding ENC(value here)
# refer to a mock endpoint name by that encrypted password
cool.result=mock:{{cool.password}}
# here is a password which is encrypted
cool.password=ENC(bsW9uV37gQ0QHFu7KO03Ww==)
Example with Spring XML
In Spring XML you need to configure the JasyptPropertiesParser which is
shown below. Then the Camel Properties component is told to use jasypt as
the properties parser, which means Jasypt have its chance to decrypt values
looked up in the properties.
The Properties component can also be inlined inside the tag
which is shown below. Notice how we use the propertiesParserRef
attribute to refer to Jasypt.
See Also
▪ Security
▪ Properties
▪ Encrypted passwords in ActiveMQ - ActiveMQ has a similar feature as
this camel-jasypt component
JAVASPACE COMPONENT
Available as of Camel 2.1
The javaspace component is a transport for working with any JavaSpace
compliant implementation and this component has been tested with both the
Blitz implementation and the GigaSpace implementation .
This component can be used for sending and receiving any object inheriting
from the Jini net.jini.core.entry.Entry class. It is also possible to pass
the bean ID of a template that can be used for reading/taking the entries
from the space.
This component can be used for sending/receiving any serializable object
acting as a sort of generic transport. The JavaSpace component contains a
special optimization for dealing with the BeanExchange. It can be used to
invoke a POJO remotely, using a JavaSpace as a transport.
This latter feature can provide a simple implementation of the master/worker
pattern, where a POJO provides the business logic for the worker.
Look at the test cases for examples of various use cases for this component.
Maven users will need to add the following dependency to their pom.xml
for this component:
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org.apache.camelcamel-javaspacex.x.x
URI format
javaspace:jini://host[?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Value
Description
spaceName
null
Specifies the JavaSpace name.
verb
take
Specifies the verb for getting JavaSpace entries. The values can be: take or read.
transactional
false
If true, sending and receiving entries is performed within a transaction.
transactionalTimeout
Long.MAX_VALUE
Specifies the transaction timeout.
concurrentConsumers
1
Specifies the number of concurrent consumers getting entries from the JavaSpace.
templateId
null
If present, this option specifies the Spring bean ID of the template to use for reading/taking
entries.
Examples
Sending and Receiving Entries
// sending route
from("direct:input")
.to("javaspace:jini://localhost?spaceName=mySpace");
// receiving Route
from("javaspace:jini://localhost?spaceName=mySpace&templateId=template&verb=take&concurrentConsumers=1
.to("mock:foo");
In this case the payload can be any object that inherits from the Jini Entry
type.
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Sending and receiving serializable objects
Using the preceding routes, it is also possible to send and receive any
serializable object. The JavaSpace component detects that the payload is not
a Jini Entry and then it automatically wraps the payload with a Camel Jini
Entry. In this way, a JavaSpace can be used as a generic transport
mechanism.
Using JavaSpace as a remote invocation transport
The JavaSpace component has been tailored to work in combination with the
Camel bean component. It is therefore possible to call a remote POJO using
JavaSpace as the transport:
// client side
from("direct:input")
.to("javaspace:jini://localhost?spaceName=mySpace");
// server side
from("javaspace:jini://localhost?concurrentConsumers=10&spaceName=mySpace")
.to("mock:foo");
In the code there are two test cases showing how to use a POJO to realize the
master/worker pattern. The idea is to use the POJO to provide the business
logic and rely on Camel for sending/receiving requests/replies with the proper
correlation.
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
JBI COMPONENT
The jbi component is implemented by the ServiceMix Camel module and
provides integration with a JBI Normalized Message Router, such as the one
provided by Apache ServiceMix.
The following code:
from("jbi:endpoint:http://foo.bar.org/MyService/MyEndpoint")
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See below for information about how to use StreamSource types
from ServiceMix in Camel.
Automatically exposes a new endpoint to the bus, where the service QName
is {http://foo.bar.org}MyService and the endpoint name is MyEndpoint
(see URI-format).
When a JBI endpoint appears at the end of a route, for example:
to("jbi:endpoint:http://foo.bar.org/MyService/MyEndpoint")
The messages sent by this producer endpoint are sent to the already
deployed JBI endpoint.
URI format
jbi:service:serviceNamespace[sep]serviceName[?options]
jbi:endpoint:serviceNamespace[sep]serviceName[sep]endpointName[?options]
jbi:name:endpointName[?options]
The separator that should be used in the endpoint URL is:
• / (forward slash), if serviceNamespace starts with http://, or
• : (colon), if serviceNamespace starts with urn:foo:bar.
For more details of valid JBI URIs see the ServiceMix URI Guide.
Using the jbi:service: or jbi:endpoint: URI formats sets the service
QName on the JBI endpoint to the one specified. Otherwise, the default
Camel JBI Service QName is used, which is:
{http://activemq.apache.org/camel/schema/jbi}endpoint
You can append query options to the URI in the following format,
?option=value&option=value&...
Examples
jbi:service:http://foo.bar.org/MyService
jbi:endpoint:urn:foo:bar:MyService:MyEndpoint
jbi:endpoint:http://foo.bar.org/MyService/MyEndpoint
jbi:name:cheese
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URI options
Name
Default value
Description
mep
MEP of the
Camel
Exchange
Allows users to override the MEP
set on the Exchange object. Valid
values for this option are in-only,
in-out, robust-in-out and inoptional-out.
operation
Value of the
jbi.operation
header
property
Specifies the JBI operation for the
MessageExchange. If no value is
supplied, the JBI binding will use
the value of the jbi.operation
header property.
basic
Default value (basic) will check if
headers are serializable by looking
at the type, setting this option to
strict will detect objects that can
not be serialized although they
implement the Serializable
interface. Set to nocheck to disable
this check altogether, note that this
should only be used for in-memory
transports like SEDAFlow,
otherwise you can expect to get
NotSerializableException
thrown at runtime.
false
false: send any exceptions thrown
from the Camel route back
unmodified
true: convert all exceptions to a JBI
FaultException (can be used to
avoid non-serializable exceptions
or to implement generic error
handling
serialization
convertException
Examples
jbi:service:http://foo.bar.org/MyService?mep=in-out
InOut JBI MessageExchanges)
jbi:endpoint:urn:foo:bar:MyService:MyEndpoint?mep=in
(override the MEP, use
(override the MEP, use
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InOnly JBI MessageExchanges)
jbi:endpoint:urn:foo:bar:MyService:MyEndpoint?operation={http://www.mycompany.org}AddNumbers
(overide the operation for the JBI Exchange to {http://www.mycompany.org}AddNumbers)
Using Stream bodies
If you are using a stream type as the message body, you should be aware
that a stream is only capable of being read once. So if you enable DEBUG
logging, the body is usually logged and thus read. To deal with this, Camel
has a streamCaching option that can cache the stream, enabling you to read
it multiple times.
from("jbi:endpoint:http://foo.bar.org/MyService/
MyEndpoint").streamCaching().to("xslt:transform.xsl", "bean:doSomething");
From Camel 1.5 onwards, the stream caching is default enabled, so it is not
necessary to set the streamCaching() option.
In Camel 2.0 we store big input streams (by default, over 64K) in a temp file
using CachedOutputStream. When you close the input stream, the temp file
will be deleted.
Creating a JBI Service Unit
If you have some Camel routes that you want to deploy inside JBI as a
Service Unit, you can use the JBI Service Unit Archetype to create a new
Maven project for the Service Unit.
If you have an existing Maven project that you need to convert into a JBI
Service Unit, you may want to consult ServiceMix Maven JBI Plugins for
further help. The key steps are as follows:
• Create a Spring XML file at src/main/resources/camelcontext.xml to bootstrap your routes inside the JBI Service Unit.
• Change the POM file's packaging to jbi-service-unit.
Your pom.xml should look something like this to enable the jbi-serviceunit packaging:
4.0.0myGroupId
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myArtifactIdjbi-service-unit1.0-SNAPSHOTA Camel based JBI Service Unithttp://www.myorganization.org1.0.03.3org.apache.servicemixservicemix-camel${servicemix-version}org.apache.servicemixservicemix-core${servicemix-version}providedinstallorg.apache.maven.pluginsmaven-compiler-plugin1.51.5org.apache.servicemix.toolingjbi-maven-plugin${servicemix-version}true
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See Also
•
•
•
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
ServiceMix Camel module
Using Camel with ServiceMix
Cookbook on using Camel with ServiceMix
JCR COMPONENT
The jcr component allows you to add nodes to a JCR compliant content
repository (for example, Apache Jackrabbit).
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-jcrx.x.x
URI format
jcr://user:password@repository/path/to/node
Usage
The repository element of the URI is used to look up the JCR Repository
object in the Camel context registry.
If a message is sent to a JCR producer endpoint:
• A new node is created in the content repository,
• All the message properties of the IN message are transformed to JCR
Value instances and added to the new node,
• The node's UUID is returned in the OUT message.
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Message properties
All message properties are converted to node properties, except for the
CamelJcrNodeName property (you can refer to JcrConstants.NODE_NAME in
your code), which is used to determine the node name.
Example
The snippet below creates a node named node under the /home/test node in
the content repository. One additional attribute is added to the node as well:
my.contents.property which will contain the body of the message being
sent.
from("direct:a").setProperty(JcrConstants.JCR_NODE_NAME, constant("node"))
.setProperty("my.contents.property", body()).to("jcr://user:pass@repository/home/
test");
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
JDBC COMPONENT
The jdbc component enables you to access databases through JDBC, where
SQL queries and operations are sent in the message body. This component
uses the standard JDBC API, unlike the SQL Component component, which
uses spring-jdbc.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-jdbcx.x.x
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This component can only be used to define producer endpoints,
which means that you cannot use the JDBC component in a from()
statement.
This component can not be used as a Transactional Client. If you
need transaction support in your route, you should use the SQL
component instead.
URI format
jdbc:dataSourceName[?options]
This component only supports producer endpoints.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
readSize
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Default
Value
Description
0 / 2000
The default maximum
number of rows that can
be read by a polling
query. The default value
is 2000 for Camel 1.5.0
or older. In newer
releases the default
value is 0.
statement.
useJDBC4ColumnNameAndLabelSemantics
null
Camel 2.1: Sets
additional options on
the
java.sql.Statement
that is used behind the
scenes to execute the
queries. For instance,
statement.maxRows=10.
For detailed
documentation, see the
java.sql.Statement
javadoc documentation.
true
Camel 1.6.3/2.2: Sets
whether to use JDBC 4/3
column label/name
semantics. You can use
this option to turn it
false in case you have
issues with your JDBC
driver to select data.
This only applies when
using SQL SELECT using
aliases (e.g. SQL
SELECT id as
identifier, name as
given_name from
persons).
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resetAutoCommit
true
Camel 2.9: Camel will
set the autoCommit on
the JDBC connection to
be false, commit the
change after executed
the statement and reset
the autoCommit flag of
the connection at the
end, if the
resetAutoCommit is
true. If the JDBC
connection doesn't
support to reset the
autoCommit flag, you
can set the
resetAutoCommit flag to
be false, and Camel will
not try to reset the
autoCommit flag.
Result
The result is returned in the OUT body as an ArrayList>. The List object contains the list of rows and the Map objects
contain each row with the String key as the column name.
Note: This component fetches ResultSetMetaData to be able to return
the column name as the key in the Map.
Message Headers
Header
Description
CamelJdbcRowCount
If the query is a SELECT, query the row count is
returned in this OUT header.
CamelJdbcUpdateCount
If the query is an UPDATE, query the update
count is returned in this OUT header.
Samples
In the following example, we fetch the rows from the customer table.
First we register our datasource in the Camel registry as testdb:
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JndiRegistry reg = super.createRegistry();
reg.bind("testdb", ds);
return reg;
Then we configure a route that routes to the JDBC component, so the SQL will
be executed. Note how we refer to the testdb datasource that was bound in
the previous step:
// lets add simple route
public void configure() throws Exception {
from("direct:hello").to("jdbc:testdb?readSize=100");
}
Or you can create a DataSource in Spring like this:
select * from customer
We create an endpoint, add the SQL query to the body of the IN message,
and then send the exchange. The result of the query is returned in the OUT
body:
// first we create our exchange using the endpoint
Endpoint endpoint = context.getEndpoint("direct:hello");
Exchange exchange = endpoint.createExchange();
// then we set the SQL on the in body
exchange.getIn().setBody("select * from customer order by ID");
// now we send the exchange to the endpoint, and receives the response from Camel
Exchange out = template.send(endpoint, exchange);
// assertions of the response
assertNotNull(out);
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assertNotNull(out.getOut());
ArrayList> data = out.getOut().getBody(ArrayList.class);
assertNotNull("out body could not be converted to an ArrayList - was: "
+ out.getOut().getBody(), data);
assertEquals(2, data.size());
HashMap row = data.get(0);
assertEquals("cust1", row.get("ID"));
assertEquals("jstrachan", row.get("NAME"));
row = data.get(1);
assertEquals("cust2", row.get("ID"));
assertEquals("nsandhu", row.get("NAME"));
If you want to work on the rows one by one instead of the entire ResultSet at
once you need to use the Splitter EIP such as:
from("direct:hello")
// here we split the data from the testdb into new messages one by one
// so the mock endpoint will receive a message per row in the table
.to("jdbc:testdb").split(body()).to("mock:result");
Sample - Polling the database every minute
If we want to poll a database using the JDBC component, we need to combine
it with a polling scheduler such as the Timer or Quartz etc. In the following
example, we retrieve data from the database every 60 seconds:
from("timer://foo?period=60000").setBody(constant("select * from
customer")).to("jdbc:testdb").to("activemq:queue:customers");
See Also
•
•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
SQL
JETTY COMPONENT
The jetty component provides HTTP-based endpoints for consuming HTTP
requests. That is, the Jetty component behaves as a simple Web server.
Jetty can also be used as a http client which mean you can also use it with
Camel as a [Producer].
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Upgrading from Jetty 6 to 7
You can read more about upgrading Jetty here
Stream
Jetty is stream based, which means the input it receives is
submitted to Camel as a stream. That means you will only be able
to read the content of the stream once.
If you find a situation where the message body appears to be
empty or you need to access the data multiple times (eg: doing
multicasting, or redelivery error handling)
you should use Stream caching or convert the message body to a
String which is safe to be re-read multiple times.
URI format
jetty:http://hostname[:port][/resourceUri][?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Value
Description
sessionSupport
false
Specifies whether to enable the session manager on the server side of Jetty.
httpClient.XXX
null
Camel 1.6.0/2.0: Configuration of Jetty's HttpClient. For example, setting
httpClient.idleTimeout=30000 sets the idle timeout to 30 seconds.
httpBindingRef
null
Camel 1.6.0/2.0: Reference to an org.apache.camel.component.http.HttpBinding in the
Registry. HttpBinding can be used to customize how a response should be written.
jettyHttpBindingRef
null
Camel 2.6.0+: Reference to an org.apache.camel.component.jetty.JettyHttpBinding in the
Registry. JettyHttpBinding can be used to customize how a response should be written.
matchOnUriPrefix
false
Camel 2.0: Whether or not the CamelServlet should try to find a target consumer by matching
the URI prefix if no exact match is found. See here How do I let Jetty match wildcards.
handlers
null
Camel 1.6.1/2.0: Specifies a comma-delimited set of org.mortbay.jetty.Handler instances in
your Registry (such as your Spring ApplicationContext). These handlers are added to the Jetty
servlet context (for example, to add security).
chunked
true
Camel 2.2: If this option is false Jetty servlet will disable the HTTP streaming and set the contentlength header on the response
enableJmx
false
Camel 2.3: If this option is true, Jetty JMX support will be enabled for this endpoint. See Jetty JMX
support for more details.
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false
Camel 2.3: Determines whether or not the raw input stream from Jetty is cached or not (Camel
will read the stream into a in memory/overflow to file, Stream caching) cache. By default Camel
will cache the Jetty input stream to support reading it multiple times to ensure it Camel can
retrieve all data from the stream. However you can set this option to true when you for example
need to access the raw stream, such as streaming it directly to a file or other persistent store.
DefaultHttpBinding will copy the request input stream into a stream cache and put it into
message body if this option is false to support reading the stream multiple times. If you use Jetty
to bridge/proxy an endpoint then consider enabling this option to improve performance, in case
you do not need to read the message payload multiple times.
bridgeEndpoint
false
Camel 2.1: If the option is true , HttpProducer will ignore the Exchange.HTTP_URI header, and
use the endpoint's URI for request. You may also set the throwExceptionOnFailure to be false
to let the HttpProducer send all the fault response back.
Camel 2.3: If the option is true, HttpProducer and CamelServlet will skip the gzip processing if
the content-encoding is "gzip". Also consider setting disableStreamCache to true to optimize
when bridging.
enableMultipartFilter
true
Camel 2.5: Whether Jetty org.eclipse.jetty.servlets.MultiPartFilter is enabled or not.
You should set this value to false when bridging endpoints, to ensure multipart requests is
proxied/bridged as well.
multipartFilterRef
null
Camel 2.6: Allows using a custom multipart filter. Note: setting multipartFilterRef forces the
value of enableMultipartFilter to true.
FiltersRef
null
Camel 2.9: Allows using a custom filters which is putted into a list and can be find in the Registry
continuationTimeout
null
Camel 2.6: Allows to set a timeout in millis when using Jetty as consumer (server). By default
Jetty uses 30000. You can use a value of <= 0 to never expire. If a timeout occurs then the
request will be expired and Jetty will return back a http error 503 to the client. This option is only
in use when using Jetty with the Asynchronous Routing Engine.
useContinuation
true
Camel 2.6: Whether or not to use Jetty continuations for the Jetty Server.
sslContextParametersRef
null
Camel 2.8: Reference to a org.apache.camel.util.jsse.SSLContextParameters in the
Registry. This reference overrides any configured SSLContextParameters at the component
level. See Using the JSSE Configuration Utility.
disableStreamCache
Message Headers
Camel uses the same message headers as the HTTP component.
From Camel 2.2, it also uses (Exchange.HTTP_CHUNKED,CamelHttpChunked)
header to turn on or turn off the chuched encoding on the camel-jetty
consumer.
Camel also populates all request.parameter and request.headers. For
example, given a client request with the URL, http://myserver/
myserver?orderid=123, the exchange will contain a header named orderid
with the value 123. This feature was introduced in Camel 1.5.
From Camel 1.6.3 and Camel 2.2.0, you can get the request.parameter
from the message header not only from Get Method, but also other HTTP
method.
Usage
The Jetty component only supports consumer endpoints. Therefore a Jetty
endpoint URI should be used only as the input for a Camel route (in a
from() DSL call). To issue HTTP requests against other HTTP endpoints, use
the HTTP Component
Component Options
The JettyHttpComponent provides the following options:
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Name
Default
Value
Description
enableJmx
false
Camel 2.3: If this option is true, Jetty JMX support will be enabled for this endpoint. See
Jetty JMX support for more details.
sslKeyPassword
null
Consumer only: The password for the keystore when using SSL.
sslPassword
null
Consumer only: The password when using SSL.
sslKeystore
null
Consumer only: The path to the keystore.
minThreads
null
Camel 2.5 Consumer only: To set a value for minimum number of threads in server
thread pool.
maxThreads
null
Camel 2.5 Consumer only: To set a value for maximum number of threads in server
thread pool.
threadPool
null
Camel 2.5 Consumer only: To use a custom thread pool for the server.
sslSocketConnectors
null
Camel 2.3 Consumer only: A map which contains per port number specific SSL
connectors. See section SSL support for more details.
socketConnectors
null
Camel 2.5 Consumer only: A map which contains per port number specific HTTP
connectors. Uses the same principle as sslSocketConnectors and therefore see section
SSL support for more details.
sslSocketConnectorProperties
null
Camel 2.5 Consumer only. A map which contains general SSL connector properties. See
section SSL support for more details.
socketConnectorProperties
null
Camel 2.5 Consumer only. A map which contains general HTTP connector properties.
Uses the same principle as sslSocketConnectorProperties and therefore see section SSL
support for more details.
httpClient
null
Producer only: To use a custom HttpClient with the jetty producer.
httpClientMinThreads
null
Producer only: To set a value for minimum number of threads in HttpClient thread pool.
httpClientMaxThreads
null
Producer only: To set a value for maximum number of threads in HttpClient thread pool.
httpClientThreadPool
null
Producer only: To use a custom thread pool for the client.
sslContextParameters
null
Camel 2.8: To configure a custom SSL/TLS configuration options at the component level.
See Using the JSSE Configuration Utility for more details.
Sample
In this sample we define a route that exposes a HTTP service at
http://localhost:8080/myapp/myservice:
from("jetty:http://localhost:{{port}}/myapp/myservice").process(new MyBookService());
Our business logic is implemented in the MyBookService class, which
accesses the HTTP request contents and then returns a response.
Note: The assert call appears in this example, because the code is part of
an unit test.
public class MyBookService implements Processor {
public void process(Exchange exchange) throws Exception {
// just get the body as a string
String body = exchange.getIn().getBody(String.class);
// we have access to the HttpServletRequest here and we can grab it if we
need it
HttpServletRequest req = exchange.getIn().getBody(HttpServletRequest.class);
assertNotNull(req);
// for unit testing
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Usage of localhost
When you specify localhost in a URL, Camel exposes the endpoint
only on the local TCP/IP network interface, so it cannot be accessed
from outside the machine it operates on.
If you need to expose a Jetty endpoint on a specific network interface, the
numerical IP address of this interface should be used as the host. If you
need to expose a Jetty endpoint on all network interfaces, the 0.0.0.0
address should be used.
assertEquals("bookid=123", body);
// send a html response
exchange.getOut().setBody("Book 123 is Camel in
Action");
}
}
The following sample shows a content-based route that routes all requests
containing the URI parameter, one, to the endpoint, mock:one, and all others
to mock:other.
from("jetty:" + serverUri)
.choice()
.when().simple("${header.one}").to("mock:one")
.otherwise()
.to("mock:other");
So if a client sends the HTTP request, http://serverUri?one=hello, the
Jetty component will copy the HTTP request parameter, one to the
exchange's in.header. We can then use the simple language to route
exchanges that contain this header to a specific endpoint and all others to
another. If we used a language more powerful than Simple--such as EL or
OGNL--we could also test for the parameter value and do routing based on
the header value as well.
Session Support
The session support option, sessionSupport, can be used to enable a
HttpSession object and access the session object while processing the
exchange. For example, the following route enables sessions:
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The myCode Processor can be instantiated by a Spring bean element:
Where the processor implementation can access the HttpSession as follows:
public void process(Exchange exchange) throws Exception {
HttpSession session = exchange.getIn(HttpMessage.class).getRequest().getSession();
...
}
SSL Support (HTTPS)
Using the JSSE Configuration Utility
As of Camel 2.8, the Jetty component supports SSL/TLS configuration through
the Camel JSSE Configuration Utility. This utility greatly decreases the
amount of component specific code you need to write and is configurable at
the endpoint and component levels. The following examples demonstrate
how to use the utility with the Jetty component.
Programmatic configuration of the component
KeyStoreParameters ksp = new KeyStoreParameters();
ksp.setResource("/users/home/server/keystore.jks");
ksp.setPassword("keystorePassword");
KeyManagersParameters kmp = new KeyManagersParameters();
kmp.setKeyStore(ksp);
kmp.setKeyPassword("keyPassword");
SSLContextParameters scp = new SSLContextParameters();
scp.setKeyManagers(kmp);
JettyComponent jettyComponent = getContext().getComponent("jetty",
JettyComponent.class);
jettyComponent.setSslContextParameters(scp);
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Spring DSL based configuration of endpoint
...
...
...
...
Configuring Jetty Directly
Jetty provides SSL support out of the box. To enable Jetty to run in SSL mode,
simply format the URI with the https:// prefix---for example:
Jetty also needs to know where to load your keystore from and what
passwords to use in order to load the correct SSL certificate. Set the following
JVM System Properties:
until Camel 2.2
• jetty.ssl.keystore specifies the location of the Java keystore file,
which contains the Jetty server's own X.509 certificate in a key entry.
A key entry stores the X.509 certificate (effectively, the public key)
and also its associated private key.
• jetty.ssl.password the store password, which is required to access
the keystore file (this is the same password that is supplied to the
keystore command's -storepass option).
• jetty.ssl.keypassword the key password, which is used to access
the certificate's key entry in the keystore (this is the same password
that is supplied to the keystore command's -keypass option).
from Camel 2.3 onwards
• org.eclipse.jetty.ssl.keystore specifies the location of the Java
keystore file, which contains the Jetty server's own X.509 certificate
in a key entry. A key entry stores the X.509 certificate (effectively,
the public key) and also its associated private key.
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• org.eclipse.jetty.ssl.password the store password, which is
required to access the keystore file (this is the same password that is
supplied to the keystore command's -storepass option).
• org.eclipse.jetty.ssl.keypassword the key password, which is
used to access the certificate's key entry in the keystore (this is the
same password that is supplied to the keystore command's keypass option).
For details of how to configure SSL on a Jetty endpoint, read the following
documentation at the Jetty Site: http://docs.codehaus.org/display/JETTY/
How+to+configure+SSL
Some SSL properties aren't exposed directly by Camel, however Camel
does expose the underlying SslSocketConnector, which will allow you to set
properties like needClientAuth for mutual authentication requiring a client
certificate or wantClientAuth for mutual authentication where a client doesn't
need a certificate but can have one. There's a slight difference between
Camel 1.6.x and 2.x:
Camel 1.x
until Camel 2.2
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Camel 2.3, 2.4
*From Camel 2.5 we switch to use SslSelectChannelConnector *
The value you use as keys in the above map is the port you configure Jetty to
listen on.
Configuring general SSL properties
Available as of Camel 2.5
Instead of a per port number specific SSL socket connector (as shown
above) you can now configure general properties which applies for all SSL
socket connectors (which is not explicit configured as above with the port
number as entry).
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How to obtain reference to the X509Certificate
Jetty stores a reference to the certificate in the HttpServletRequest which you
can access from code as follows:
HttpServletRequest req = exchange.getIn().getBody(HttpServletRequest.class);
X509Certificate cert = (X509Certificate)
req.getAttribute("javax.servlet.request.X509Certificate")
Configuring general HTTP properties
Available as of Camel 2.5
Instead of a per port number specific HTTP socket connector (as shown
above) you can now configure general properties which applies for all HTTP
socket connectors (which is not explicit configured as above with the port
number as entry).
Default behavior for returning HTTP status codes
The default behavior of HTTP status codes is defined by the
org.apache.camel.component.http.DefaultHttpBinding class, which
handles how a response is written and also sets the HTTP status code.
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If the exchange was processed successfully, the 200 HTTP status code is
returned.
If the exchange failed with an exception, the 500 HTTP status code is
returned, and the stacktrace is returned in the body. If you want to specify
which HTTP status code to return, set the code in the
HttpProducer.HTTP_RESPONSE_CODE header of the OUT message.
Customizing HttpBinding
Available as of Camel 1.5.1/2.0
By default, Camel uses the
org.apache.camel.component.http.DefaultHttpBinding to handle how a
response is written. If you like, you can customize this behavior either by
implementing your own HttpBinding class or by extending
DefaultHttpBinding and overriding the appropriate methods.
The following example shows how to customize the DefaultHttpBinding
in order to change how exceptions are returned:
public class MyJettyHttpBinding extends DefaultJettyHttpBinding {
@Override
protected void populateResponse(Exchange exchange, JettyContentExchange
httpExchange, Message in,
HeaderFilterStrategy strategy, int responseCode)
throws IOException {
Message answer = exchange.getOut();
answer.setHeaders(in.getHeaders());
answer.setHeader(Exchange.HTTP_RESPONSE_CODE, responseCode);
answer.setBody("Not exactly the message the server returned.");
}
}
We can then create an instance of our binding and register it in the Spring
registry as follows:
And then we can reference this binding when we define the route:
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Jetty handlers and security configuration
Available as of Camel 1.6.1/2.0: You can configure a list of Jetty handlers
on the endpoint, which can be useful for enabling advanced Jetty security
features. These handlers are configured in Spring XML as follows:
<-- Jetty Security handling -->
And from Camel 2.3 onwards you can configure a list of Jetty handlers as
follows:
<-- Jetty Security handling -->
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You can then define the endpoint as:
from("jetty:http://0.0.0.0:9080/myservice?handlers=securityHandler")
If you need more handlers, set the handlers option equal to a commaseparated list of bean IDs.
How to return a custom HTTP 500 reply message
You may want to return a custom reply message when something goes
wrong, instead of the default reply message Camel Jetty replies with.
You could use a custom HttpBinding to be in control of the message
mapping, but often it may be easier to use Camel's Exception Clause to
construct the custom reply message. For example as show here, where we
return Dude something went wrong with HTTP error code 500:
from("jetty://http://localhost:{{port}}/myserver")
// use onException to catch all exceptions and return a custom reply message
.onException(Exception.class)
.handled(true)
// create a custom failure response
.transform(constant("Dude something went wrong"))
// we must remember to set error code 500 as handled(true)
// otherwise would let Camel thing its a OK response (200)
.setHeader(Exchange.HTTP_RESPONSE_CODE, constant(500))
.end()
// now just force an exception immediately
.throwException(new IllegalArgumentException("I cannot do this"));
Multi-part Form support
From Camel 2.3.0, camel-jetty support to multipart form post out of box. The
submitted form-data are mapped into the message header. Camel-jetty
creates an attachment for each uploaded file. The file name is mapped to the
name of the attachment. The content type is set as the content type of the
attachment file name. You can find the example here.
Listing 78. Note: getName() functions as shown below in versions 2.5 and higher.
In earlier versions you receive the temporary file name for the attachment instead
// Set the jetty temp directory which store the file for multi part form
// camel-jetty will clean up the file after it handled the request.
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// The option works rightly from Camel 2.4.0
getContext().getProperties().put("CamelJettyTempDir", "target");
from("jetty://http://localhost:{{port}}/test").process(new Processor() {
public void process(Exchange exchange) throws Exception {
Message in = exchange.getIn();
assertEquals("Get a wrong attachement size", 1, in.getAttachments().size());
// The file name is attachment id
DataHandler data = in.getAttachment("NOTICE.txt");
assertNotNull("Should get the DataHandle NOTICE.txt", data);
// This assert is wrong, but the correct content-type (application/
octet-stream)
// will not be returned until Jetty makes it available - currently the
content-type
// returned is just the default for FileDataHandler (for the implentation
being used)
//assertEquals("Get a wrong content type", "text/plain",
data.getContentType());
assertEquals("Got the wrong name", "NOTICE.txt", data.getName());
assertTrue("We should get the data from the DataHandle", data.getDataSource()
.getInputStream().available() > 0);
// The other form date can be get from the message header
exchange.getOut().setBody(in.getHeader("comment"));
}
});
Jetty JMX support
From Camel 2.3.0, camel-jetty supports the enabling of Jetty's JMX
capabilities at the component and endpoint level with the endpoint
configuration taking priority. Note that JMX must be enabled within the Camel
context in order to enable JMX support in this component as the component
provides Jetty with a reference to the MBeanServer registered with the Camel
context. Because the camel-jetty component caches and reuses Jetty
resources for a given protocol/host/port pairing, this configuration option will
only be evaluated during the creation of the first endpoint to use a protocol/
host/port pairing. For example, given two routes created from the following
XML fragments, JMX support would remain enabled for all endpoints listening
on "https://0.0.0.0".
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The camel-jetty component also provides for direct configuration of the Jetty
MBeanContainer. Jetty creates MBean names dynamically. If you are running
another instance of Jetty outside of the Camel context and sharing the same
MBeanServer between the instances, you can provide both instances with a
reference to the same MBeanContainer in order to avoid name collisions
when registering Jetty MBeans.
See Also
•
•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
HTTP
JING COMPONENT
The Jing component uses the Jing Library to perform XML validation of the
message body using either
• RelaxNG XML Syntax
• RelaxNG Compact Syntax
Maven users will need to add the following dependency to their pom.xml for
this component:
org.apache.camelcamel-jingx.x.x
Note that the MSV component can also support RelaxNG XML syntax.
URI format
rng:someLocalOrRemoteResource
rnc:someLocalOrRemoteResource
Where rng means use the RelaxNG XML Syntax whereas rnc means use
RelaxNG Compact Syntax. The following examples show possible URI values
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Example
Description
rng:foo/bar.rng
References the XML file foo/bar.rng on the classpath
rnc:
http://foo.com/
bar.rnc
References the RelaxNG Compact Syntax file from the
URL, http://foo.com/bar.rnc
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Option
Default
Description
useDom
false
Camel 2.0: Specifies whether DOMSource/DOMResult
or SaxSource/SaxResult should be used by the
validator.
Example
The following example shows how to configure a route from the endpoint
direct:start which then goes to one of two endpoints, either mock:valid or
mock:invalid based on whether or not the XML matches the given RelaxNG
Compact Syntax schema (which is supplied on the classpath).
org.apache.camel.ValidationException
See Also
• Configuring Camel
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• Component
• Endpoint
• Getting Started
JMS COMPONENT
The JMS component allows messages to be sent to (or consumed from) a JMS
Queue or Topic. The implementation of the JMS Component uses Spring's JMS
support for declarative transactions, using Spring's JmsTemplate for sending
and a MessageListenerContainer for consuming.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-jmsx.x.x
URI format
jms:[queue:|topic:]destinationName[?options]
Where destinationName is a JMS queue or topic name. By default, the
destinationName is interpreted as a queue name. For example, to connect
to the queue, FOO.BAR use:
jms:FOO.BAR
You can include the optional queue: prefix, if you prefer:
jms:queue:FOO.BAR
To connect to a topic, you must include the topic: prefix. For example, to
connect to the topic, Stocks.Prices, use:
jms:topic:Stocks.Prices
You append query options to the URI using the following format,
?option=value&option=value&...
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Using ActiveMQ
If you are using Apache ActiveMQ, you should prefer the ActiveMQ
component as it has been optimized for ActiveMQ. All of the options
and samples on this page are also valid for the ActiveMQ
component.
Transacted and caching
See section Transactions and Cache Levels below if you are using
transactions with JMS as it can impact performance.
Notes
Using ActiveMQ
The JMS component reuses Spring 2's JmsTemplate for sending messages.
This is not ideal for use in a non-J2EE container and typically requires some
caching in the JMS provider to avoid poor performance.
If you intend to use Apache ActiveMQ as your Message Broker - which is a
good choice as ActiveMQ rocks
, then we recommend that you either:
• Use the ActiveMQ component, which is already optimized to use
ActiveMQ efficiently
• Use the PoolingConnectionFactory in ActiveMQ.
Transactions and Cache Levels
If you are consuming messages and using transactions (transacted=true)
then the default settings for cache level can impact performance.
If you are using XA transactions then you cannot cache as it can cause the
XA transaction not to work properly.
If you are not using XA, then you should consider caching as it speedup
performance, such as setting cacheLevelName=CACHE_CONSUMER.
Through Camel 2.7.x, the default setting for cacheLevelName is
CACHE_CONSUMER. You will need to explicitly set
cacheLevelName=CACHE_NONE.
In Camel 2.8 onwards, the default setting for cacheLevelName is CACHE_AUTO.
This default auto detects the mode and sets the cache level accordingly to:
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▪ CACHE_CONSUMER = if transacted=false
▪ CACHE_NONE = if transacted=true
So you can say the default setting is conservative. Consider using
cacheLevelName=CACHE_CONSUMER if you are using non-XA transactions.
Durable Subscriptions
If you wish to use durable topic subscriptions, you need to specify both
clientId and durableSubscriptionName. The value of the clientId must
be unique and can only be used by a single JMS connection instance in your
entire network. You may prefer to use Virtual Topics instead to avoid this
limitation. More background on durable messaging here.
Message Header Mapping
When using message headers, the JMS specification states that header
names must be valid Java identifiers. So, by default, Camel ignores any
headers that do not match this rule. So try to name your headers as if they
are valid Java identifiers. One benefit of doing this is that you can then use
your headers inside a JMS Selector (whose SQL92 syntax mandates Java
identifier syntax for headers).
From Camel 1.4 onwards, a simple strategy for mapping header names is
used by default. The strategy is to replace any dots in the header name with
the underscore character and to reverse the replacement when the header
name is restored from a JMS message sent over the wire. What does this
mean? No more losing method names to invoke on a bean component, no
more losing the filename header for the File Component, and so on.
The current header name strategy for accepting header names in Camel is
as follows:
▪ Replace all dots with underscores (for example,
org.apache.camel.MethodName becomes
org_apache_camel_MethodName).
▪ Test if the name is a valid java identifier using the JDK core classes.
▪ If the test success, the header is added and sent over the wire;
otherwise it is dropped (and logged at DEBUG level).
In Camel 2.0 this strategy has been change a bit to use the following
replacement strategy:
▪ Dots are replaced by _DOT_ and the replacement is reversed when
Camel consume the message
▪ Hyphen is replaced by _HYPHEN_ and the replacement is reversed
when Camel consumes the message
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Options
You can configure many different properties on the JMS endpoint which map
to properties on the JMSConfiguration POJO.
The options are divided into two tables, the first one with the most common
options used. The latter contains the rest.
Most commonly used options
Option
Default
Value
Description
clientId
null
Sets the JMS client ID to use. Note that this value, if specified, must be unique and can only be
used by a single JMS connection instance. It is typically only required for durable topic
subscriptions. You may prefer to use Virtual Topics instead.
concurrentConsumers
1
Specifies the default number of concurrent consumers.
disableReplyTo
false
If true, a producer will behave like a InOnly exchange with the exception that JMSReplyTo header
is sent out and not be suppressed like in the case of InOnly. Like InOnly the producer will not
wait for a reply. A consumer with this flag will behave like InOnly. This feature can be used to
bridge InOut requests to another queue so that a route on the other queue will send it´s
response directly back to the original JMSReplyTo.
durableSubscriptionName
null
The durable subscriber name for specifying durable topic subscriptions. The clientId option
must be configured as well.
maxConcurrentConsumers
1
Specifies the maximum number of concurrent consumers.
preserveMessageQos
false
Camel 2.0: Set to true, if you want to send message using the QoS settings specified on the
message, instead of the QoS settings on the JMS endpoint. The following three headers are
considered JMSPriority, JMSDeliveryMode, and JMSExpiration. You can provide all or only
some of them. If not provided, Camel will fall back to use the values from the endpoint instead.
So, when using this option, the headers override the values from the endpoint. The
explicitQosEnabled option, by contrast, will only use options set on the endpoint, and not
values from the message header.
replyTo
null
Provides an explicit ReplyTo destination, which overrides any incoming value of
Message.getJMSReplyTo(). If you do Request Reply over JMS then read the section further below
for more details.
replyToType
null
Camel 2.9: Allows to explicit specify which kind of strategy to use for replyTo queues when doing
request/reply over JMS. Possible values are: Temporary, Shared, or Exclusive. By default Camel
will use temporary queues. However if replyTo has been configured, then Shared is used by
default. This option allows you to use exclusive instead of shared queues. See further below for
more details, and especially the notes about the implications if running in a clustered
environment.
requestTimeout
20000
Producer only: The timeout for waiting for a reply when using the InOut Exchange Pattern (in
milliseconds). The default is 20 seconds. See below in section About time to live for more details.
selector
null
Sets the JMS Selector, which is an SQL 92 predicate that is used to filter messages within the
broker. You may have to encode special characters such as = as %3D Before Camel 2.3.0, we
don't support this option in CamelConsumerTemplate
timeToLive
null
When sending messages, specifies the time-to-live of the message (in milliseconds). See below in
section About time to live for more details.
transacted
false
Specifies whether to use transacted mode for sending/receiving messages using the InOnly
Exchange Pattern.
false
Camel 2.1: Specifies whether to test the connection on startup. This ensures that when Camel
starts that all the JMS consumers have a valid connection to the JMS broker. If a connection
cannot be granted then Camel throws an exception on startup. This ensure that Camel is not
started with failed connections. From Camel 2.8 onwards also the JMS producers is tested as
well.
testConnectionOnStartup
All the other options
Option
Default Value
Description
autoStartup
true
Specifies whether the consumer container should auto-startup.
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Mapping to Spring JMS
Many of these properties map to properties on Spring JMS, which
Camel uses for sending and receiving messages. So you can get
more information about these properties by consulting the relevant
Spring documentation.
acceptMessagesWhileStopping
false
Specifies whether the consumer accept messages while it is stopping.
acknowledgementModeName
AUTO_ACKNOWLEDGE
The JMS acknowledgement name, which is one of: TRANSACTED,
CLIENT_ACKNOWLEDGE, AUTO_ACKNOWLEDGE, DUPS_OK_ACKNOWLEDGE
acknowledgementMode
-1
The JMS acknowledgement mode defined as an Integer. Allows you to set
vendor-specific extensions to the acknowledgment mode. For the regular
modes, it is preferable to use the acknowledgementModeName instead.
false
If true, Camel will always make a JMS message copy of the message when it
is passed to the producer for sending. Copying the message is needed in
some situations, such as when a replyToDestinationSelectorName is set
(incidentally, Camel will set the alwaysCopyMessage option to true, if a
replyToDestinationSelectorName is set)
false
Camel 2.9: Whether the JmsConsumer processes the Exchange
asynchronously. If enabled then the JmsConsumer may pickup the next
message from the JMS queue, while the previous message is being
processed asynchronously (by the Asynchronous Routing Engine). This
means that messages may be processed not 100% strictly in order. If
disabled (as default) then the Exchange is fully processed before the
JmsConsumer will pickup the next message from the JMS queue. Note if
transacted has been enabled, then asyncConsumer=true does not run
asynchronously, as transactions must be executed synchronously (Camel 3.0
may support async transactions).
alwaysCopyMessage
asyncConsumer
cacheLevelName
▪
Sets the cache level by name for the underlying JMS resources. Possible
values are: CACHE_AUTO, CACHE_CONNECTION, CACHE_CONSUMER, CACHE_NONE,
and CACHE_SESSION. The default setting for Camel 2.8 and newer is
CACHE_AUTO. For Camel 2.7.1 and older the default is CACHE_CONSUMER. See
the Spring documentation and Transactions Cache Levels for more
information.
cacheLevel
▪
Sets the cache level by ID for the underlying JMS resources. See
cacheLevelName option for more details.
consumerType
Default
The consumer type to use, which can be one of: Simple or Default. The
consumer type determines which Spring JMS listener to use. Default will use
org.springframework.jms.listener.DefaultMessageListenerContainer,
Simple will use
org.springframework.jms.listener.SimpleMessageListenerContainer.
This option was temporary removed in Camel 2.7 and 2.8. But has been
added back from Camel 2.9 onwards.
connectionFactory
null
The default JMS connection factory to use for the
listenerConnectionFactory and templateConnectionFactory, if neither
is specified.
deliveryPersistent
true
Specifies whether persistent delivery is used by default.
destination
null
Camel 2.0: Specifies the JMS Destination object to use on this endpoint.
destinationName
null
Camel 2.0: Specifies the JMS destination name to use on this endpoint.
destinationResolver
null
A pluggable
org.springframework.jms.support.destination.DestinationResolver
that allows you to use your own resolver (for example, to lookup the real
destination in a JNDI registry).
false
Camel 2.8: Use this option to force disabling time to live. For example when
you do request/reply over JMS, then Camel will by default use the
requestTimeout value as time to live on the message being send. The
problem is that the sender and receiver systems have to have their clocks
synchronized, so they are in sync. This is not always so easy to archive. So
you can use disableTimeToLive=true to not set a time to live value on the
send message. Then the message will not expire on the receiver system. See
below in section About time to live for more details.
disableTimeToLive
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eagerLoadingOfProperties
false
Enables eager loading of JMS properties as soon as a message is received,
which is generally inefficient, because the JMS properties might not be
required. But this feature can sometimes catch early any issues with the
underlying JMS provider and the use of JMS properties. This feature can also
be used for testing purposes, to ensure JMS properties can be understood
and handled correctly.
exceptionListener
null
Specifies the JMS Exception Listener that is to be notified of any underlying
JMS exceptions.
errorHandler
null
Camel 2.8.2, 2.9: Specifies a org.springframework.util.ErrorHandler
to be invoked in case of any uncaught exceptions thrown while processing a
Message. By default these exceptions will be logged at the ERROR level.
explicitQosEnabled
false
Set if the deliveryMode, priority or timeToLive qualities of service should
be used when sending messages. This option is based on Spring's
JmsTemplate. The deliveryMode, priority and timeToLive options are
applied to the current endpoint. This contrasts with the preserveMessageQos
option, which operates at message granularity, reading QoS properties
exclusively from the Camel In message headers.
exposeListenerSession
true
Specifies whether the listener session should be exposed when consuming
messages.
forceSendOriginalMessage
false
Camel 2.7: When using mapJmsMessage=false Camel will create a new JMS
message to send to a new JMS destination if you touch the headers (get or
set) during the route. Set this option to true to force Camel to send the
original JMS message that was received.
idleTaskExecutionLimit
1
Specifies the limit for idle executions of a receive task, not having received
any message within its execution. If this limit is reached, the task will shut
down and leave receiving to other executing tasks (in the case of dynamic
scheduling; see the maxConcurrentConsumers setting).
idleConsumerLimit
1
Camel 2.8.2, 2.9: Specify the limit for the number of consumers that are
allowed to be idle at any given time.
jmsMessageType
null
Camel 2.0: Allows you to force the use of a specific javax.jms.Message
implementation for sending JMS messages. Possible values are: Bytes, Map,
Object, Stream, Text. By default, Camel would determine which JMS
message type to use from the In body type. This option allows you to specify
it.
jmsKeyFormatStrategy
default
Camel 2.0: Pluggable strategy for encoding and decoding JMS keys so they
can be compliant with the JMS specification. Camel provides two
implementations out of the box: default and passthrough. The default
strategy will safely marshal dots and hyphens (. and -). The passthrough
strategy leaves the key as is. Can be used for JMS brokers which do not care
whether JMS header keys contain illegal characters. You can provide your
own implementation of the
org.apache.camel.component.jms.JmsKeyFormatStrategy and refer to it
using the # notation.
jmsOperations
null
Allows you to use your own implementation of the
org.springframework.jms.core.JmsOperations interface. Camel uses
JmsTemplate as default. Can be used for testing purpose, but not used much
as stated in the spring API docs.
lazyCreateTransactionManager
true
Camel 2.0: If true, Camel will create a JmsTransactionManager, if there is
no transactionManager injected when option transacted=true.
listenerConnectionFactory
null
The JMS connection factory used for consuming messages.
mapJmsMessage
true
Camel 1.6.2/2.0: Specifies whether Camel should auto map the received
JMS message to an appropiate payload type, such as
javax.jms.TextMessage to a String etc. See section about how mapping
works below for more details.
maxMessagesPerTask
-1
The number of messages per task. -1 is unlimited.
maximumBrowseSize
-1
Limits the number of messages fetched at most, when browsing endpoints
using Browse or JMX API.
messageConverter
null
Camel 1.6.2/2.0: To use a custom Spring
org.springframework.jms.support.converter.MessageConverter so you
can be 100% in control how to map to/from a javax.jms.Message.
messageIdEnabled
true
When sending, specifies whether message IDs should be added.
messageTimestampEnabled
true
Specifies whether timestamps should be enabled by default on sending
messages.
password
null
The password for the connector factory.
priority
4
Values greater than 1 specify the message priority when sending (where 0 is
the lowest priority and 9 is the highest). The explicitQosEnabled option
must also be enabled in order for this option to have any effect.
pubSubNoLocal
false
Specifies whether to inhibit the delivery of messages published by its own
connection.
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receiveTimeout
None
The timeout for receiving messages (in milliseconds).
recoveryInterval
5000
Specifies the interval between recovery attempts, i.e. when a connection is
being refreshed, in milliseconds. The default is 5000 ms, that is, 5 seconds.
replyToDestinationSelectorName
null
Sets the JMS Selector using the fixed name to be used so you can filter out
your own replies from the others when using a shared queue (that is, if you
are not using a temporary reply queue).
replyToDeliveryPersistent
true
Specifies whether to use persistent delivery by default for replies.
subscriptionDurable
false
@deprecated: Enabled by default, if you specify a durableSubscriberName
and a clientId.
taskExecutor
null
Allows you to specify a custom task executor for consuming messages.
taskExecutorSpring2
null
Camel 2.6: To use when using Spring 2.x with Camel. Allows you to specify
a custom task executor for consuming messages.
templateConnectionFactory
null
The JMS connection factory used for sending messages.
transactedInOut
false
@deprecated: Specifies whether to use transacted mode for sending
messages using the InOut Exchange Pattern. Applies only to producer
endpoints. See section Enabling Transacted Consumption for more details.
transactionManager
null
The Spring transaction manager to use.
transactionName
"JmsConsumer[destinationName]"
The name of the transaction to use.
transactionTimeout
null
The timeout value of the transaction, if using transacted mode.
transferException
false
Camel 2.0: If enabled and you are using Request Reply messaging (InOut)
and an Exchange failed on the consumer side, then the caused Exception
will be send back in response as a javax.jms.ObjectMessage. If the client is
Camel, the returned Exception is rethrown. This allows you to use Camel
JMS as a bridge in your routing - for example, using persistent queues to
enable robust routing. Notice that if you also have transferExchange
enabled, this option takes precedence. The caught exception is required to
be serializable. The original Exception on the consumer side can be
wrapped in an outer exception such as
org.apache.camel.RuntimeCamelException when returned to the producer.
transferExchange
false
Camel 2.0: You can transfer the exchange over the wire instead of just the
body and headers. The following fields are transferred: In body, Out body,
Fault body, In headers, Out headers, Fault headers, exchange properties,
exchange exception. This requires that the objects are serializable. Camel
will exclude any non-serializable objects and log it at WARN level.
username
null
The username for the connector factory.
useMessageIDAsCorrelationID
false
Specifies whether JMSMessageID should always be used as
JMSCorrelationID for InOut messages.
useVersion102
false
@deprecated (removed from Camel 2.5 onwards): Specifies whether
the old JMS API should be used.
Message Mapping between JMS and Camel
Camel automatically maps messages between javax.jms.Message and
org.apache.camel.Message.
When sending a JMS message, Camel converts the message body to the
following JMS message types:
753
Body Type
JMS Message
String
javax.jms.TextMessage
org.w3c.dom.Node
javax.jms.TextMessage
Map
javax.jms.MapMessage
java.io.Serializable
javax.jms.ObjectMessage
byte[]
javax.jms.BytesMessage
java.io.File
javax.jms.BytesMessage
java.io.Reader
javax.jms.BytesMessage
java.io.InputStream
javax.jms.BytesMessage
java.nio.ByteBuffer
javax.jms.BytesMessage
Comment
The DOM will be converted to String.
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
When receiving a JMS message, Camel converts the JMS message to the
following body type:
JMS Message
Body Type
javax.jms.TextMessage
String
javax.jms.BytesMessage
byte[]
javax.jms.MapMessage
Map
javax.jms.ObjectMessage
Object
Disabling auto-mapping of JMS messages
Available as of Camel 1.6.2/2.0
You can use the mapJmsMessage option to disable the auto-mapping above.
If disabled, Camel will not try to map the received JMS message, but instead
uses it directly as the payload. This allows you to avoid the overhead of
mapping and let Camel just pass through the JMS message. For instance, it
even allows you to route javax.jms.ObjectMessage JMS messages with
classes you do not have on the classpath.
Using a custom MessageConverter
Available as of Camel 1.6.2/2.0
You can use the messageConverter option to do the mapping yourself in a
Spring org.springframework.jms.support.converter.MessageConverter
class.
For example, in the route below we use a custom message converter when
sending a message to the JMS order queue:
from("file://inbox/
order").to("jms:queue:order?messageConverter=#myMessageConverter");
You can also use a custom message converter when consuming from a JMS
destination.
Controlling the mapping strategy selected
Available as of Camel 2.0
You can use the jmsMessageType option on the endpoint URL to force a
specific message type for all messages.
In the route below, we poll files from a folder and send them as
javax.jms.TextMessage as we have forced the JMS producer endpoint to
use text messages:
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from("file://inbox/order").to("jms:queue:order?jmsMessageType=Text");
You can also specify the message type to use for each messabe by setting
the header with the key CamelJmsMessageType. For example:
from("file://inbox/order").setHeader("CamelJmsMessageType",
JmsMessageType.Text).to("jms:queue:order");
The possible values are defined in the enum class,
org.apache.camel.jms.JmsMessageType.
Message format when sending
The exchange that is sent over the JMS wire must conform to the JMS
Message spec.
For the exchange.in.header the following rules apply for the header
keys:
▪ Keys starting with JMS or JMSX are reserved.
▪ exchange.in.headers keys must be literals and all be valid Java
identifiers (do not use dots in the key name).
▪ From Camel 1.4 until Camel 1.6.x, Camel automatically replaces all
dots with underscores in key names. This replacement is reversed
when Camel consumes JMS messages.
▪ From Camel 2.0 onwards, Camel replaces dots & hyphens and the
reverse when when consuming JMS messages:
. is replaced by _DOT_ and the reverse replacement when Camel
consumes the message.
- is replaced by _HYPHEN_ and the reverse replacement when Camel
consumes the message.
▪ See also the option jmsKeyFormatStrategy introduced in Camel
2.0, which allows you to use your own custom strategy for formatting
keys.
For the exchange.in.header, the following rules apply for the header
values:
▪ The values must be primitives or their counter objects (such as
Integer, Long, Character). The types, String, CharSequence, Date,
BigDecimal and BigInteger are all converted to their toString()
representation. All other types are dropped.
Camel will log with category
org.apache.camel.component.jms.JmsBinding at DEBUG level if it drops a
given header value. For example:
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2008-07-09 06:43:04,046 [main
] DEBUG JmsBinding
- Ignoring non primitive header: order of class:
org.apache.camel.component.jms.issues.DummyOrder with value: DummyOrder{orderId=333,
itemId=4444, quantity=2}
Message format when receiving
Camel adds the following properties to the Exchange when it receives a
message:
Property
Type
Description
org.apache.camel.jms.replyDestination
javax.jms.Destination
The reply destination.
Camel adds the following JMS properties to the In message headers when it
receives a JMS message:
Header
Type
Description
JMSCorrelationID
String
The JMS correlation ID.
JMSDeliveryMode
int
The JMS delivery mode.
JMSDestination
javax.jms.Destination
The JMS destination.
JMSExpiration
long
The JMS expiration.
JMSMessageID
String
The JMS unique message ID.
JMSPriority
int
The JMS priority (with 0 as the lowest priority and 9 as the highest).
JMSRedelivered
boolean
Is the JMS message redelivered.
JMSReplyTo
javax.jms.Destination
The JMS reply-to destination.
JMSTimestamp
long
The JMS timestamp.
JMSType
String
The JMS type.
JMSXGroupID
String
The JMS group ID.
As all the above information is standard JMS you can check the JMS
documentation for further details.
About using Camel to send and receive messages and JMSReplyTo
The JMS component is complex and you have to pay close attention to how it
works in some cases. So this is a short summary of some of the areas/pitfalls
to look for.
When Camel sends a message using its JMSProducer, it checks the
following conditions:
▪ The message exchange pattern,
▪ Whether a JMSReplyTo was set in the endpoint or in the message
headers,
▪ Whether any of the following options have been set on the JMS
endpoint: disableReplyTo, preserveMessageQos,
explicitQosEnabled.
All this can be a tad complex to understand and configure to support your
use case.
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JmsProducer
The JmsProducer behaves as follows, depending on configuration:
Exchange
Pattern
Other
options
Description
InOut
-
Camel will expect a reply, set a temporary JMSReplyTo, and after sending the message, it will start to
listen for the reply message on the temporary queue.
InOut
JMSReplyTo is
set
Camel will expect a reply and, after sending the message, it will start to listen for the reply message on the
specified JMSReplyTo queue.
InOnly
-
Camel will send the message and not expect a reply.
InOnly
JMSReplyTo is
set
By default, Camel discards the JMSReplyTo destination and clears the JMSReplyTo header before sending
the message. Camel then sends the message and does not expect a reply. Camel logs this in the log at
WARN level (changed to DEBUG level from Camel 2.6 onwards. You can use preserveMessageQuo=true to
instruct Camel to keep the JMSReplyTo. In all situations the JmsProducer does not expect any reply and
thus continue after sending the message.
JmsConsumer
The JmsConsumer behaves as follows, depending on configuration:
Exchange Pattern
Other options
Description
InOut
-
Camel will send the reply back to the JMSReplyTo queue.
InOnly
-
Camel will not send a reply back, as the pattern is InOnly.
-
disableReplyTo=true
This option suppresses replies.
So pay attention to the message exchange pattern set on your exchanges.
If you send a message to a JMS destination in the middle of your route you
can specify the exchange pattern to use, see more at Request Reply.
This is useful if you want to send an InOnly message to a JMS topic:
from("activemq:queue:in")
.to("bean:validateOrder")
.to(ExchangePattern.InOnly, "activemq:topic:order")
.to("bean:handleOrder");
Reuse endpoint and send to different destinations computed at
runtime
Available as of Camel 1.6.2/2.0
If you need to send messages to a lot of different JMS destinations, it makes
sense to reuse a JMS endpoint and specify the real destination in a message
header. This allows Camel to reuse the same endpoint, but send to different
destinations. This greatly reduces the number of endpoints created and
economizes on memory and thread resources.
You can specify the destination in the following headers:
757
Header
Type
Description
CamelJmsDestination
javax.jms.Destination
Camel 2.0: A destination object.
CamelJmsDestinationName
String
Camel 1.6.2/2.0: The destination name.
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
For example, the following route shows how you can compute a destination
at run time and use it to override the destination appearing in the JMS URL:
from("file://inbox")
.to("bean:computeDestination")
.to("activemq:queue:dummy");
The queue name, dummy, is just a placeholder. It must be provided as part of
the JMS endpoint URL, but it will be ignored in this example.
In the computeDestination bean, specify the real destination by setting
the CamelJmsDestinationName header as follows:
public void setJmsHeader(Exchange exchange) {
String id = ....
exchange.getIn().setHeader("CamelJmsDestinationName", "order:" + id");
}
Then Camel will read this header and use it as the destination instead of the
one configured on the endpoint. So, in this example Camel sends the
message to activemq:queue:order:2, assuming the id value was 2.
If both the CamelJmsDestination and the CamelJmsDestinationName
headers are set, CamelJmsDestination takes priority.
Configuring different JMS providers
You can configure your JMS provider in Spring XML as follows:
Basically, you can configure as many JMS component instances as you wish
and give them a unique name using the id attribute. The preceding
example configures an activemq component. You could do the same to
configure MQSeries, TibCo, BEA, Sonic and so on.
Once you have a named JMS component, you can then refer to endpoints
within that component using URIs. For example for the component name,
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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activemq, you can then refer to destinations using the URI format,
activemq:[queue:|topic:]destinationName. You can use the same
approach for all other JMS providers.
This works by the SpringCamelContext lazily fetching components from
the spring context for the scheme name you use for Endpoint URIs and
having the Component resolve the endpoint URIs.
Using JNDI to find the ConnectionFactory
If you are using a J2EE container, you might need to look up JNDI to find the
JMS ConnectionFactory rather than use the usual mechanism in
Spring. You can do this using Spring's factory bean or the new Spring XML
namespace. For example:
See The jee schema in the Spring reference documentation for more details
about JNDI lookup.
Concurrent Consuming
A common requirement with JMS is to consume messages concurrently in
multiple threads in order to make an application more responsive. You can
set the concurrentConsumers option to specify the number of threads
servicing the JMS endpoint, as follows:
from("jms:SomeQueue?concurrentConsumers=20").
bean(MyClass.class);
You can configure this option in one of the following ways:
• On the JmsComponent,
• On the endpoint URI or,
• By invoking setConcurrentConsumers() directly on the
JmsEndpoint.
Request-reply over JMS
Camel supports Request Reply over JMS. In essence the MEP of the Exchange
should be InOut when you send a message to a JMS queue.
The JmsProducer detects the InOut and provides a JMSReplyTo header with
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the reply destination to be used. By default Camel uses a temporary queue,
but you can use the replyTo option on the endpoint to specify a fixed reply
queue (see more below about fixed reply queue).
Camel will automatic setup a consumer which listen on the reply queue, so
you should not do anything.
This consumer is a Spring DefaultMessageListenerContainer which listen
for replies. However it's fixed to 1 concurrent consumer.
That means replies will be processed in sequence as there are only 1 thread
to process the replies. If you want to process replies faster, then we need to
use concurrency. But not using the concurrentConsumer option. We should
use the threads from the Camel DSL instead, as shown in the route below:
from(xxx)
.inOut().to("activemq:queue:foo")
.threads(5)
.to(yyy)
.to(zzz);
In this route we instruct Camel to route replies asynchronously using a thread
pool with 5 threads.
Request-reply over JMS and using a shared fixed reply
queue
If you use a fixed reply queue when doing Request Reply over JMS as shown
in the example below, then pay attention.
from(xxx)
.inOut().to("activemq:queue:foo?replyTo=bar")
.to(yyy)
In this example the fixed reply queue named "bar" is used. By default Camel
assumes the queue is shared when using fixed reply queues, and therefore it
uses a JMSSelector to only pickup the expected reply messages (eg based
on the JMSCorrelationID). See next section for exclusive fixed reply queues.
That means its not as fast as temporary queues. You can speedup how often
Camel will pull for reply messages using the receiveTimeout option. By
default its 1000 millis. So to make it faster you can set it to 250 millis to pull
4 times per second as shown:
from(xxx)
.inOut().to("activemq:queue:foo?replyTo=bar&receiveTimeout=250")
.to(yyy)
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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Notice this will cause the Camel to send pull requests to the message broker
more frequent, and thus require more network traffic.
It is generally recommended to use temporary queues if possible.
Request-reply over JMS and using an exclusive fixed
reply queue
Available as of Camel 2.9
In the previous example, Camel would anticipate the fixed reply queue
named "bar" was shared, and thus it uses a JMSSelector to only consume
reply messages which it expects. However there is a drawback doing this as
JMS selectos is slower. Also the consumer on the reply queue is slower to
update with new JMS selector ids. In fact it only updates when the
receiveTimeout option times out, which by default is 1 second. So in theory
the reply messages could take up till about 1 sec to be detected. On the
other hand if the fixed reply queue is exclusive to the Camel reply consumer,
then we can avoid using the JMS selectors, and thus be more performant. In
fact as fast as using temporary queues. So in Camel 2.9 onwards we
introduced the ReplyToType option which you can configure to Exclusive
to tell Camel that the reply queue is exclusive as shown in the example
below:
from(xxx)
.inOut().to("activemq:queue:foo?replyTo=bar?replyToType=Exclusive")
.to(yyy)
Mind that the queue must be exclusive to each and every endpoint. So if you
have two routes, then they each need an unique reply queue as shown in the
next example:
from(xxx)
.inOut().to("activemq:queue:foo?replyTo=bar?replyToType=Exclusive")
.to(yyy)
from(aaa)
.inOut().to("activemq:queue:order?replyTo=order.reply?replyToType=Exclusive")
.to(bbb)
The same applies if you run in a clustered environment. Then each node in
the cluster must use an unique reply queue name. As otherwise each node in
the cluster may pickup messages which was intended as a reply on another
node. For clustered environments its recommended to use shared reply
queues instead.
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Synchronizing clocks between senders and receivers
When doing messaging between systems, its desirable that the systems
have synchronized clocks. For example when sending a JMS message, then
you can set a time to live value on the message. Then the receiver can
inspect this value, and determine if the message is already expired, and thus
drop the message instead of consume and process it. However this requires
that both sender and receiver have synchronized clocks. If you are using
ActiveMQ then you can use the timestamp plugin to synchronize clocks.
About time to live
Read first above about synchronized clocks.
When you do request/reply (InOut) over JMS with Camel then Camel uses a
timeout on the sender side, which is default 20 seconds from the
requestTimeout option. You can control this by setting a higher/lower value.
However the time to live value is still set on the JMS message being send. So
that requires the clocks to be synchronized between the systems. If they are
not, then you may want to disable the time to live value being set. This is
now possible using the disableTimeToLive option from Camel 2.8 onwards.
So if you set this option to disableTimeToLive=true, then Camel does not
set any time to live value when sending JMS messages. But the request
timeout is still active. So for example if you do request/reply over JMS and
have disabled time to live, then Camel will still use a timeout by 20 seconds
(the requestTimeout option). That option can of course also be configured.
So the two options requestTimeout and disableTimeToLive gives you fine
grained control when doing request/reply.
When you do fire and forget (InOut) over JMS with Camel then Camel by
default does not set any time to live value on the message. You can
configure a value by using the timeToLive option. For example to indicate a
5 sec., you set timeToLive=5000. The option disableTimeToLive can be
used to force disabling the time to live, also for InOnly messaging. The
requestTimeout option is not being used for InOnly messaging.
Enabling Transacted Consumption
A common requirement is to consume from a queue in a transaction and
then process the message using the Camel route. To do this, just ensure that
you set the following properties on the component/endpoint:
• transacted = true
• transactionManager = a Transsaction Manager - typically the
JmsTransactionManager
See the Transactional Client EIP pattern for further details.
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Transactions and Request Reply over JMS
When using Request Reply over JMS you cannot use a single
transaction; JMS will not send any messages until a commit is
performed, so the server side won't receive anything at all until the
transaction commits. Therefore to use Request Reply you must
commit a transaction after sending the request and then use a
separate transaction for receiving the response.
To address this issue the JMS component uses different properties to
specify transaction use for oneway messaging and request reply
messaging:
The transacted property applies only to the InOnly message Exchange
Pattern (MEP).
The transactedInOut property applies to the InOut(Request Reply)
message Exchange Pattern (MEP).
If you want to use transactions for Request Reply(InOut MEP), you must
set transactedInOut=true.
Using JMSReplyTo for late replies
Avaiable as of Camel 2.0
When using Camel as a JMS listener, it sets an Exchange property with the
value of the ReplyTo javax.jms.Destination object, having the key
ReplyTo. You can obtain this Destination as follows:
Destination replyDestination =
exchange.getIn().getHeader(JmsConstants.JMS_REPLY_DESTINATION, Destination.class);
And then later use it to send a reply using regular JMS or Camel.
// we need to pass in the JMS component, and in this sample we use ActiveMQ
JmsEndpoint endpoint = JmsEndpoint.newInstance(replyDestination,
activeMQComponent);
// now we have the endpoint we can use regular Camel API to send a message to it
template.sendBody(endpoint, "Here is the late reply.");
A different solution to sending a reply is to provide the replyDestination
object in the same Exchange property when sending. Camel will then pick up
this property and use it for the real destination. The endpoint URI must
include a dummy destination, however. For example:
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CH AP T E R 11 - C OM P ON E N T A P P E N DIX
// we pretend to send it to some non existing dummy queue
template.send("activemq:queue:dummy, new Processor() {
public void process(Exchange exchange) throws Exception {
// and here we override the destination with the ReplyTo destination
object so the message is sent to there instead of dummy
exchange.getIn().setHeader(JmsConstants.JMS_DESTINATION,
replyDestination);
exchange.getIn().setBody("Here is the late reply.");
}
}
Using a request timeout
In the sample below we send a Request Reply style message Exchange (we
use the requestBody method = InOut) to the slow queue for further
processing in Camel and we wait for a return reply:
// send a in-out with a timeout for 5 sec
Object out = template.requestBody("activemq:queue:slow?requestTimeout=5000", "Hello
World");
Samples
JMS is used in many examples for other components as well. But we provide
a few samples below to get started.
Receiving from JMS
In the following sample we configure a route that receives JMS messages and
routes the message to a POJO:
from("jms:queue:foo").
to("bean:myBusinessLogic");
You can of course use any of the EIP patterns so the route can be context
based. For example, here's how to filter an order topic for the big spenders:
from("jms:topic:OrdersTopic").
filter().method("myBean", "isGoldCustomer").
to("jms:queue:BigSpendersQueue");
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Sending to a JMS
In the sample below we poll a file folder and send the file content to a JMS
topic. As we want the content of the file as a TextMessage instead of a
BytesMessage, we need to convert the body to a String:
from("file://orders").
convertBodyTo(String.class).
to("jms:topic:OrdersTopic");
Using Annotations
Camel also has annotations so you can use POJO Consuming and POJO
Producing.
Spring DSL sample
The preceding examples use the Java DSL. Camel also supports Spring XML
DSL. Here is the big spender sample using Spring DSL:
Other samples
JMS appears in many of the examples for other components and EIP patterns,
as well in this Camel documentation. So feel free to browse the
documentation. If you have time, check out the this tutorial that uses JMS but
focuses on how well Spring Remoting and Camel works together TutorialJmsRemoting.
Using JMS as a Dead Letter Queue storing Exchange
Available as of Camel 2.0
Normally, when using JMS as the transport, it only transfers the body and
headers as the payload. If you want to use JMS with a Dead Letter Channel,
using a JMS queue as the Dead Letter Queue, then normally the caused
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Exception is not stored in the JMS message. You can, however, use the
transferExchange option on the JMS dead letter queue to instruct Camel to
store the entire Exchange in the queue as a javax.jms.ObjectMessage that
holds a org.apache.camel.impl.DefaultExchangeHolder. This allows you
to consume from the Dead Letter Queue and retrieve the caused exception
from the Exchange property with the key Exchange.EXCEPTION_CAUGHT. The
demo below illustrates this:
// setup error handler to use JMS as queue and store the entire Exchange
errorHandler(deadLetterChannel("jms:queue:dead?transferExchange=true"));
Then you can consume from the JMS queue and analyze the problem:
from("jms:queue:dead").to("bean:myErrorAnalyzer");
// and in our bean
String body = exchange.getIn().getBody();
Exception cause = exchange.getProperty(Exchange.EXCEPTION_CAUGHT, Exception.class);
// the cause message is
String problem = cause.getMessage();
Using JMS as a Dead Letter Channel storing error only
You can use JMS to store the cause error message or to store a custom body,
which you can initialize yourself. The following example uses the Message
Translator EIP to do a transformation on the failed exchange before it is
moved to the JMS dead letter queue:
// we sent it to a seda dead queue first
errorHandler(deadLetterChannel("seda:dead"));
// and on the seda dead queue we can do the custom transformation before its sent to
the JMS queue
from("seda:dead").transform(exceptionMessage()).to("jms:queue:dead");
Here we only store the original cause error message in the transform. You
can, however, use any Expression to send whatever you like. For example,
you can invoke a method on a Bean or use a custom processor.
Sending an InOnly message and keeping the JMSReplyTo header
When sending to a JMS destination using camel-jms the producer will use
the MEP to detect if its InOnly or InOut messaging. However there can be
times where you want to send an InOnly message but keeping the
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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JMSReplyTo header. To do so you have to instruct Camel to keep it, otherwise
the JMSReplyTo header will be dropped.
For example to send an InOnly message to the foo queue, but with a
JMSReplyTo with bar queue you can do as follows:
template.send("activemq:queue:foo?preserveMessageQos=true", new Processor() {
public void process(Exchange exchange) throws Exception {
exchange.getIn().setBody("World");
exchange.getIn().setHeader("JMSReplyTo", "bar");
}
});
Notice we use preserveMessageQos=true to instruct Camel to keep the
JMSReplyTo header.
Setting JMS provider options on the destination
Some JMS providers, like IBM's WebSphere MQ need options to be set on the
JMS destination. For example, you may need to specify the targetClient
option. Since targetClient is a WebSphere MQ option and not a Camel URI
option, you need to set that on the JMS destination name like so:
...
.setHeader("CamelJmsDestinationName", constant("queue:///MY_QUEUE?targetClient=1"))
.to("wmq:queue:MY_QUEUE?useMessageIDAsCorrelationID=true");
Some versions of WMQ won't accept this option on the destination name and
you will get an exception like:
com.ibm.msg.client.jms.DetailedJMSException: JMSCC0005: The
specified value 'MY_QUEUE?targetClient=1' is not allowed for
'XMSC_DESTINATION_NAME'
A workaround is to use a custom DestinationResolver:
JmsComponent wmq = new JmsComponent(connectionFactory);
wmq.setDestinationResolver(new DestinationResolver(){
public Destination resolveDestinationName(Session session, String
destinationName, boolean pubSubDomain) throws JMSException {
MQQueueSession wmqSession = (MQQueueSession) session;
return wmqSession.createQueue("queue:///" + destinationName +
"?targetClient=1");
}
});
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See Also
•
•
•
•
▪
▪
▪
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Configuring Camel
Component
Endpoint
Getting Started
Transactional Client
Bean Integration
Tutorial-JmsRemoting
JMSTemplate gotchas
JMX COMPONENT
Available as of Camel 2.6
Standard JMX Consumer Configuration
Component allows consumers to subscribe to an mbean's Notifications. The
component supports passing the Notification object directly through the
Exchange or serializing it to XML according to the schema provided within
this project. This is a consumer only component. Exceptions are thrown if you
attempt to create a producer for it.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-jmxx.x.x
URI Format
The component can connect to the local platform mbean server with the
following URI:
jmx://platform?options
A remote mbean server url can be provided following the initial JMX scheme
like so:
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jmx:service:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi?options
You can append query options to the URI in the following format,
?options=value&option2=value&...
URI Options
Property
Required
format
user
Description
xml
Format for the message body. Either "xml" or "raw". If xml, the notification is serialized to
xml. If raw, then the raw java object is set as the body.
Credentials for making a remote connection.
password
objectDomain
Default
Credentials for making a remote connection.
yes
The domain for the mbean you're connecting to.
objectName
The name key for the mbean you're connecting to. This value is mutually exclusive with
the object properties that get passed. (see below)
notificationFilter
Reference to a bean that implements the NotificationFilter. The #ref syntax should
be used to reference the bean via the Registry.
handback
Value to handback to the listener when a notification is received. This value will be put in
the message header with the key "jmx.handback"
ObjectName Construction
The URI must always have the objectDomain property. In addition, the URI
must contain either objectName or one or more properties that start with
"key."
Domain with Name property
When the objectName property is provided, the following constructor is used
to build the ObjectName? for the mbean:
ObjectName(String domain, String key, String value)
The key value in the above will be "name" and the value will be the value of
the objectName property.
Domain with Hashtable
ObjectName(String domain, Hashtable table)
The Hashtable is constructed by extracting properties that start with "key."
The properties will have the "key." prefixed stripped prior to building the
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Hashtable. This allows the URI to contain a variable number of properties to
identify the mbean.
Example
from("jmx:platform?objectDomain=jmxExample&key.name=simpleBean").
to("log:jmxEvent");
Full example
Monitor Type Consumer
Available as of Camel 2.8
One popular use case for JMX is creating a monitor bean to monitor an
attribute on a deployed bean. This requires writing a few lines of Java code to
create the JMX monitor and deploy it. As shown below:
CounterMonitor monitor = new CounterMonitor();
monitor.addObservedObject(makeObjectName("simpleBean"));
monitor.setObservedAttribute("MonitorNumber");
monitor.setNotify(true);
monitor.setInitThreshold(1);
monitor.setGranularityPeriod(500);
registerBean(monitor, makeObjectName("counter"));
monitor.start();
The 2.8 version introduces a new type of consumer that automatically
creates and registers a monitor bean for the specified objectName and
attribute. Additional endpoint attributes allow the user to specify the
attribute to monitor, type of monitor to create, and any other required
properties. The code snippet above is condensed into a set of endpoint
properties. The consumer uses these properties to create the
CounterMonitor, register it, and then subscribe to its changes. All of the JMX
monitor types are supported.
Example
from("jmx:platform?objectDomain=myDomain&objectName=simpleBean&" +
"monitorType=counter&observedAttribute=MonitorNumber&initThreshold=1&" +
"granularityPeriod=500").to("mock:sink");
The example above will cause a new Monitor Bean to be created and
depoyed to the local mbean server that monitors the "MonitorNumber"
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attribute on the "simpleBean." Additional types of monitor beans and options
are detailed below. The newly deployed monitor bean is automatically
undeployed when the consumer is stopped.
URI Options for Monitor Type
property
type
applies
to
description
monitorType
enum
all
one of counter, guage, string
observedAttribute
string
all
the attribute being observed
granualityPeriod
long
all
granularity period (in millis) for
the attribute being observed. As
per JMX, default is 10 seconds
initThreshold
number
counter
initial threshold value
offset
number
counter
offset value
modulus
number
counter
modulus value
differenceMode
boolean
counter,
gauge
true if difference should be
reported, false for actual value
notifyHigh
boolean
gauge
high notification on/off switch
notifyLow
boolean
gauge
low notification on/off switch
highThreshold
number
gauge
threshold for reporting high
notification
lowThreshold
number
gauge
threshold for reporting low
notificaton
notifyDiffer
boolean
string
true to fire notification when
string differs
notifyMatch
boolean
string
true to fire notification when
string matches
stringToCompare
string
string
string to compare against the
attribute value
The monitor style consumer is only supported for the local mbean server. JMX
does not currently support remote deployment of mbeans without either
having the classes already remotely deployed or an adapter library on both
the client and server to facilitate a proxy deployment.
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See Also
•
•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
Camel JMX
JPA COMPONENT
The jpa component enables you to store and retrieve Java objects from
persistent storage using EJB 3's Java Persistence Architecture (JPA), which is a
standard interface layer that wraps Object/Relational Mapping (ORM)
products such as OpenJPA, Hibernate, TopLink, and so on.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-jpax.x.x
Sending to the endpoint
You can store a Java entity bean in a database by sending it to a JPA producer
endpoint. The body of the In message is assumed to be an entity bean (that
is, a POJO with an @Entity annotation on it) or a collection or array of entity
beans.
If the body does not contain one of the previous listed types, put a
Message Translator in front of the endpoint to perform the necessary
conversion first.
Consuming from the endpoint
Consuming messages from a JPA consumer endpoint removes (or updates)
entity beans in the database. This allows you to use a database table as a
logical queue: consumers take messages from the queue and then delete/
update them to logically remove them from the queue.
If you do not wish to delete the entity bean when it has been processed,
you can specify consumeDelete=false on the URI. This will result in the
entity being processed each poll.
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If you would rather perform some update on the entity to mark it as
processed (such as to exclude it from a future query) then you can annotate
a method with @Consumed which will be invoked on your entity bean when
the entity bean is consumed.
URI format
jpa:[entityClassName][?options]
For sending to the endpoint, the entityClassName is optional. If specified, it
helps the Type Converter to ensure the body is of the correct type.
For consuming, the entityClassName is mandatory.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Value
Description
entityType
entityClassName
Overrides the entityClassName from the URI.
persistenceUnit
camel
The JPA persistence unit used by default.
consumeDelete
true
JPA consumer only: If true, the entity is deleted after it is consumed; if false, the entity is
not deleted.
consumeLockEntity
true
JPA consumer only: Specifies whether or not to set an exclusive lock on each entity bean
while processing the results from polling.
flushOnSend
true
JPA producer only: Flushes the EntityManager after the entity bean has been persisted.
maximumResults
-1
JPA consumer only: Set the maximum number of results to retrieve on the Query.
transactionManager
null
Camel 1.6.1/2.0: Specifies the transaction manager to use. If none provided, Camel will use a
JpaTransactionManager by default. Can be used to set a JTA transaction manager (for
integration with an EJB container).
consumer.delay
500
JPA consumer only: Delay in milliseconds between each poll.
consumer.initialDelay
1000
JPA consumer only: Milliseconds before polling starts.
consumer.useFixedDelay
false
JPA consumer only: Set to true to use fixed delay between polls, otherwise fixed rate is used.
See ScheduledExecutorService in JDK for details.
maxMessagesPerPoll
0
Camel 2.0: JPA consumer only: An integer value to define the maximum number of
messages to gather per poll. By default, no maximum is set. Can be used to avoid polling many
thousands of messages when starting up the server. Set a value of 0 or negative to disable.
consumer.query
JPA consumer only: To use a custom query when consuming data.
consumer.namedQuery
JPA consumer only: To use a named query when consuming data.
consumer.nativeQuery
JPA consumer only: To use a custom native query when consuming data.
consumer.resultClass
Camel 2.7: JPA consumer only: Defines the type of the returned payload (we will call
entityManager.createNativeQuery(nativeQuery, resultClass) instead of
entityManager.createNativeQuery(nativeQuery)). Without this option, we will return an
object array. Only has an affect when using in conjunction with native query when consuming
data.
usePersist
773
false
Camel 2.5: JPA producer only: Indicates to use entityManager.persist(entity) instead of
entityManager.merge(entity). Note: entityManager.persist(entity) doesn't work for
detached entities (where the EntityManager has to execute an UPDATE instead of an INSERT
query)!
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Message Headers
Camel adds the following message headers to the exchange:
Header
Type
Description
CamelJpaTemplate
JpaTemplate
Camel 2.0: The JpaTemplate object that is used to access the entity bean. You need this object in some
situations, for instance in a type converter or when you are doing some custom processing.
Configuring EntityManagerFactory
Its strongly advised to configure the JPA component to use a specific
EntityManagerFactory instance. If failed to do so each JpaEndpoint will
auto create their own instance of EntityManagerFactory which most often is
not what you want.
For example, you can instantiate a JPA component that references the
myEMFactory entity manager factory, as follows:
In Camel 2.3 the JpaComponent will auto lookup the EntityManagerFactory
from the Registry which means you do not need to configure this on the
JpaComponent as shown above. You only need to do so if there is ambiguity,
in which case Camel will log a WARN.
Configuring TransactionManager
Its strongly advised to configure the TransactionManager instance used by
the JPA component. If failed to do so each JpaEndpoint will auto create their
own instance of TransactionManager which most often is not what you
want.
For example, you can instantiate a JPA component that references the
myTransactionManager transaction manager, as follows:
In Camel 2.3 the JpaComponent will auto lookup the TransactionManager
from the Registry which means you do not need to configure this on the
JpaComponent as shown above. You only need to do so if there is ambiguity,
in which case Camel will log a WARN.
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Using a consumer with a named query
For consuming only selected entities, you can use the consumer.namedQuery
URI query option. First, you have to define the named query in the JPA Entity
class:
@Entity
@NamedQuery(name = "step1", query = "select x from MultiSteps x where x.step = 1")
public class MultiSteps {
...
}
After that you can define a consumer uri like this one:
from("jpa://org.apache.camel.examples.MultiSteps?consumer.namedQuery=step1")
.to("bean:myBusinessLogic");
Using a consumer with a query
For consuming only selected entities, you can use the consumer.query URI
query option. You only have to define the query option:
from("jpa://org.apache.camel.examples.MultiSteps?consumer.query=select o from
org.apache.camel.examples.MultiSteps o where o.step = 1")
.to("bean:myBusinessLogic");
Using a consumer with a native query
For consuming only selected entities, you can use the
consumer.nativeQuery URI query option. You only have to define the native
query option:
from("jpa://org.apache.camel.examples.MultiSteps?consumer.nativeQuery=select * from
MultiSteps where step = 1")
.to("bean:myBusinessLogic");
If you use the native query option, you will receive an object array in the
message body.
Example
See Tracer Example for an example using JPA to store traced messages into a
database.
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Using the JPA based idempotent repository
In this section we will use the JPA based idempotent repository.
First we need to setup a persistence-unit in the persistence.xml file:
org.apache.camel.processor.idempotent.jpa.MessageProcessed
Second we have to setup a org.springframework.orm.jpa.JpaTemplate
which is used by the
org.apache.camel.processor.idempotent.jpa.JpaMessageIdRepository:
Afterwards we can configure our
org.apache.camel.processor.idempotent.jpa.JpaMessageIdRepository:
And finally we can create our JPA idempotent repository in the spring XML file
as well:
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messageId
See Also
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•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
Tracer Example
JT/400 COMPONENT
The jt400 component allows you to exchanges messages with an AS/400
system using data queues.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-jt400x.x.x
URI format
jt400://user:password@system/QSYS.LIB/LIBRARY.LIB/QUEUE.DTAQ[?options]
To call remote program (Camel 2.7)
jt400://user:password@system/QSYS.LIB/LIBRARY.LIB/program.PGM[?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
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URI options
For the data queue message exchange:
Name
Default
value
Description
ccsid
default system
CCSID
Specifies the CCSID to use for the connection with the AS/400 system.
format
text
Specifies the data format for sending messages
valid options are: text (represented by String) and binary (represented by byte[])
consumer.delay
500
Delay in milliseconds between each poll.
consumer.initialDelay
1000
Milliseconds before polling starts.
consumer.userFixedDelay
false
true to use fixed delay between polls, otherwise fixed rate is used. See
ScheduledExecutorService in JDK for details.
guiAvailable
false
Camel 2.8: Specifies whether AS/400 prompting is enabled in the environment running
Camel.
For the remote program call (Camel 2.7)
Name
Default value
Description
outputFieldsIdx
Specifies which fields (program parameters) are output parameters.
fieldsLength
Specifies the fields (program parameters) length as in the AS/400 program definition.
Usage
When configured as a consumer endpoint, the endpoint will poll a data queue
on a remote system. For every entry on the data queue, a new Exchange is
sent with the entry's data in the In message's body, formatted either as a
String or a byte[], depending on the format. For a provider endpoint, the In
message body contents will be put on the data queue as either raw bytes or
text.
Remote program call (Camel 2.7)
This endpoint expects the input to be a String array and handles all the
CCSID handling trough the native jt400 library mechanisms. After the
program execution the endpoint returns a String array with the values as
they were returned by the program (the input only parameters will contain
the same data as the beginning of the invocation)
This endpoint does not implement a provider endpoint!
Example
In the snippet below, the data for an exchange sent to the direct:george
endpoint will be put in the data queue PENNYLANE in library BEATLES on a
system named LIVERPOOL.
Another user connects to the same data queue to receive the information
from the data queue and forward it to the mock:ringo endpoint.
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public class Jt400RouteBuilder extends RouteBuilder {
@Override
public void configure() throws Exception {
from("direct:george").to("jt400://GEORGE:EGROEG@LIVERPOOL/QSYS.LIB/BEATLES.LIB/
PENNYLANE.DTAQ");
from("jt400://RINGO:OGNIR@LIVERPOOL/QSYS.LIB/BEATLES.LIB/
PENNYLANE.DTAQ").to("mock:ringo");
}
}
Remote program call example (Camel 2.7)
In the snippet below, the data Exchange sent to the direct:work endpoint will
contain three string that will be used as the arguments for the program
“compute” in the library “assets”. This program will write the output values
in the 2nd and 3rd parameters. All the parameters will be sent to the
direct:play endpoint.
public class Jt400RouteBuilder extends RouteBuilder {
@Override
public void configure() throws Exception {
from("direct:work").to("jt400://GRUPO:ATWORK@server/QSYS.LIB/assets.LIB/
compute.PGM?fieldsLength=10,10,512&ouputFieldsIdx=2,3").to(“direct:play”);
}
}
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
LANGUAGE
Available as of Camel 2.5
The language component allows you to send Exchange to an endpoint
which executes a script by any of the supported Languages in Camel.
By having a component to execute language scripts, it allows more dynamic
routing capabilities. For example by using the Routing Slip or Dynamic Router
EIPs you can send messages to language endpoints where the script is
dynamic defined as well.
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This component is provided out of the box in camel-core and hence no
additional JARs is needed. You only have to include additional Camel
components if the language of choice mandates it, such as using Groovy or
JavaScript languages.
URI format
language://languageName[:script][?options]
URI Options
The component supports the following options.
Name
Default
Value
Type
Description
languageName
null
String
The name of the Language to use, such as simple, groovy, javascript etc. This option is
mandatory.
script
null
String
The script to execute.
transform
true
boolean
Whether or not the result of the script should be used as the new message body. By setting to
false the script is executed but the result of the script is discarded.
contentCache
true
boolean
Camel 2.9: Whether to cache the script if loaded from a resource.
Message Headers
The following message headers can be used to affect the behavior of the
component
Header
Description
CamelLanguageScript
The script to execute provided in the header. Takes precedence over script configured on the endpoint.
Examples
For example you can use the Simple language to Message Translator a
message:
String script = URLEncoder.encode("Hello ${body}", "UTF-8");
from("direct:start").to("language:simple:" + script).to("mock:result");
In case you want to convert the message body type you can do this as well:
String script = URLEncoder.encode("${mandatoryBodyAs(String)}", "UTF-8");
from("direct:start").to("language:simple:" + script).to("mock:result");
You can also use the Groovy language, such as this example where the input
message will by multiplied with 2:
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String script = URLEncoder.encode("request.body * 2", "UTF-8");
from("direct:start").to("language:groovy:" + script).to("mock:result");
You can also provide the script as a header as shown below. Here we use
XPath language to extract the text from the tag.
Object out = producer.requestBodyAndHeader("language:xpath", "Hello
World", Exchange.LANGUAGE_SCRIPT, "/foo/text()");
assertEquals("Hello World", out);
Loading scripts from resources
Available as of Camel 2.9
You can specify a resource uri for a script to load in either the endpoint uri,
or in the Exchange.LANGUAGE_SCRIPT header.
The uri must start with one of the following schemes: file:, classpath:, or http:
For example to load a script from the classpath:
from("direct:start")
// load the script from the classpath
.to("language:simple:classpath:org/apache/camel/component/language/
mysimplescript.txt")
.to("mock:result");
By default the script is loaded once and cached. However you can disable the
contentCache option and have the script loaded on each evaluation.
For example if the file myscript.txt is changed on disk, then the updated
script is used:
from("direct:start")
// the script will be loaded on each message, as we disabled cache
.to("language:simple:file:target/script/myscript.txt?contentCache=false")
.to("mock:result");
See Also
•
•
•
•
▪
▪
▪
781
Configuring Camel
Component
Endpoint
Getting Started
Languages
Routing Slip
Dynamic Router
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
LDAP COMPONENT
The ldap component allows you to perform searches in LDAP servers using
filters as the message payload.
This component uses standard JNDI (javax.naming package) to access the
server.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-ldapx.x.x
URI format
ldap:ldapServerBean[?options]
The ldapServerBean portion of the URI refers to a DirContext bean in the
registry. The LDAP component only supports producer endpoints, which
means that an ldap URI cannot appear in the from at the start of a route.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Value
Description
base
ou=system
The base DN for searches.
scope
subtree
Specifies how deeply to search the tree of entries, starting at the base DN. Value can be object,
onelevel, or subtree.
pageSize
no paging
used
Camel 2.6: When specified the ldap module uses paging to retrieve all results (most LDAP Servers throw
an exception when trying to retrieve more than 1000 entries in one query). To be able to use this a
LdapContext (subclass of DirContext) has to be passed in as ldapServerBean (otherwise an exception is
thrown)
returnedAttributes
depends on
LDAP Server
(could be all
or none)
Camel 2.6: Comma-separated list of attributes that should be set in each entry of the result
Result
The result is returned in the Out body as a
ArrayList object.
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DirContext
The URI, ldap:ldapserver, references a Spring bean with the ID,
ldapserver. The ldapserver bean may be defined as follows:
com.sun.jndi.ldap.LdapCtxFactoryldap://localhost:10389none
The preceding example declares a regular Sun based LDAP DirContext that
connects anonymously to a locally hosted LDAP server.
Samples
Following on from the Spring configuration above, the code sample below
sends an LDAP request to filter search a group for a member. The Common
Name is then extracted from the response.
ProducerTemplate template = exchange
.getContext().createProducerTemplate();
Collection results = (Collection) (template
.sendBody(
"ldap:ldapserver?base=ou=mygroup,ou=groups,ou=system",
"(member=uid=huntc,ou=users,ou=system)"));
if (results.size() > 0) {
// Extract what we need from the device's profile
Iterator resultIter = results.iterator();
SearchResult searchResult = (SearchResult) resultIter
.next();
Attributes attributes = searchResult
.getAttributes();
Attribute deviceCNAttr = attributes.get("cn");
String deviceCN = (String) deviceCNAttr.get();
...
If no specific filter is required - for example, you just need to look up a single
entry - specify a wildcard filter expression. For example, if the LDAP entry has
a Common Name, use a filter expression like:
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DirContext objects are not required to support concurrency by
contract. It is therefore important that the directory context is
declared with the setting, scope="prototype", in the bean
definition or that the context supports concurrency. In the Spring
framework, prototype scoped objects are instantiated each time
they are looked up.
Camel 1.6.1 and Camel 2.0 include a fix to support concurrency for
LDAP producers. ldapServerBean contexts are now looked up each
time a request is sent to the LDAP server. In addition, the contexts
are released as soon as the producer completes.
(cn=*)
Binding using credentials
A Camel end user donated this sample code he used to bind to the ldap
server using credentials.
Properties props = new Properties();
props.setProperty(Context.INITIAL_CONTEXT_FACTORY,
"com.sun.jndi.ldap.LdapCtxFactory");
props.setProperty(Context.PROVIDER_URL, "ldap://localhost:389");
props.setProperty(Context.URL_PKG_PREFIXES, "com.sun.jndi.url");
props.setProperty(Context.REFERRAL, "ignore");
props.setProperty(Context.SECURITY_AUTHENTICATION, "simple");
props.setProperty(Context.SECURITY_PRINCIPAL, "cn=Manager");
props.setProperty(Context.SECURITY_CREDENTIALS, "secret");
SimpleRegistry reg = new SimpleRegistry();
reg.put("myldap", new InitialLdapContext(props, null));
CamelContext context = new DefaultCamelContext(reg);
context.addRoutes(
new RouteBuilder() {
public void configure() throws Exception {
from("direct:start").to("ldap:myldap?base=ou=test");
}
}
);
context.start();
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ProducerTemplate template = context.createProducerTemplate();
Endpoint endpoint = context.getEndpoint("direct:start");
Exchange exchange = endpoint.createExchange();
exchange.getIn().setBody("(uid=test)");
Exchange out = template.send(endpoint, exchange);
Collection data = out.getOut().getBody(Collection.class);
assert data != null;
assert !data.isEmpty();
System.out.println(out.getOut().getBody());
context.stop();
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
LOG COMPONENT
The log: component logs message exchanges to the underlying logging
mechanism.
Camel 2.7 or better uses sfl4j which allows you to configure logging via,
among others:
• Log4j
• Logback
• JDK Util Logging logging
Camel 2.6 or lower uses commons-logging which allows you to configure
logging via, among others:
• Log4j
• JDK Util Logging logging
• SimpleLog - a simple provider in commons-logging
Refer to the commons-logging user guide for a more complete overview of
how to use and configure commons-logging.
URI format
log:loggingCategory[?options]
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Where loggingCategory is the name of the logging category to use. You can
append query options to the URI in the following format,
?option=value&option=value&...
For example, a log endpoint typically specifies the logging level using the
level option, as follows:
log:org.apache.camel.example?level=DEBUG
The default logger logs every exchange (regular logging). But Camel also
ships with the Throughput logger, which is used whenever the groupSize
option is specified.
Options
Option
Default
Type
Description
level
INFO
String
Logging level to use. Possible values: FATAL, ERROR, WARN, INFO, DEBUG, TRACE, OFF
groupSize
null
Integer
An integer that specifies a group size for throughput logging.
groupInterval
null
Integer
Camel 2.6: If specified will group message stats by this time interval (in millis)
groupDelay
0
Integer
Camel 2.6: Set the initial delay for stats (in millis)
groupActiveOnly
true
boolean
Camel 2.6: If true, will hide stats when no new messages have been received for a time
interval, if false, show stats regardless of message traffic
Throughput logging options. By default regular logging is used.
note: groupDelay and groupActiveOnly are only applicable when using
groupInterval
Formatting
The log formats the execution of exchanges to log lines.
By default, the log uses LogFormatter to format the log output, where
LogFormatter has the following options:
Option
Default
Description
showAll
false
Quick option for turning all options on. (multiline, maxChars has to be manually set if to be used)
showExchangeId
false
Show the unique exchange ID.
showExchangePattern
true
Camel 2.3: Shows the Message Exchange Pattern (or MEP for short).
showProperties
false
Show the exchange properties.
showHeaders
false
Show the In message headers.
showBodyType
true
Show the In body Java type.
showBody
true
Show the In body.
showOut
false
If the exchange has an Out message, show the Out message.
showException
false
Camel 2.0: If the exchange has an exception, show the exception message (no stack trace).
showCaughtException
false
Camel 2.0: If the exchange has a caught exception, show the exception message (no stack trace). A
caught exception is stored as a property on the exchange (using the key
Exchange.EXCEPTION_CAUGHT) and for instance a doCatch can catch exceptions. See Try Catch Finally.
showStackTrace
false
Camel 2.0: Show the stack trace, if an exchange has an exception. Only effective if one of showAll,
showException or showCaughtException are enabled.
showFiles
false
Camel 2.9: Whether Camel should show file bodies or not (eg such as java.io.File).
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Also a log in the DSL
In Camel 2.2 onwards there is a log directly in the DSL, but it has
a different purpose. Its meant for lightweight and human logs. See
more details at LogEIP.
showFuture
false
Camel 2.1: Whether Camel should show java.util.concurrent.Future bodies or not. If enabled
Camel could potentially wait until the Future task is done. Will by default not wait.
showStreams
false
Camel 2.8: Whether Camel should show stream bodies or not (eg such as java.io.InputStream).
Beware if you enable this option then you may not be able later to access the message body as the
stream have already been read by this logger. To remedy this you have to use Stream caching.
multiline
false
If true, each piece of information is logged on a new line.
maxChars
Camel 2.0: Limits the number of characters logged per line.
Regular logger sample
In the route below we log the incoming orders at DEBUG level before the order
is processed:
from("activemq:orders").to("log:com.mycompany.order?level=DEBUG").to("bean:processOrder");
Or using Spring XML to define the route:
Regular logger with formatter sample
In the route below we log the incoming orders at INFO level before the order
is processed.
from("activemq:orders").
to("log:com.mycompany.order?showAll=true&multiline=true").to("bean:processOrder");
Throughput logger with groupSize sample
In the route below we log the throughput of the incoming orders at DEBUG
level grouped by 10 messages.
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Logging stream bodies
Camel will by default not log stream or files bodies. You can force
Camel to log those by setting the property on the CamelContext
properties
camelContext.getProperties().put(Exchange.LOG_DEBUG_BODY_STREAMS, true);
from("activemq:orders").
to("log:com.mycompany.order?level=DEBUG?groupSize=10").to("bean:processOrder");
Throughput logger with groupInterval sample
This route will result in message stats logged every 10s, with an initial 60s
delay and stats should be displayed even if there isn't any message traffic.
from("activemq:orders").
to("log:com.mycompany.order?level=DEBUG?groupInterval=10000&groupDelay=60000&groupActiveOnly=false").t
The following will be logged:
"Received: 1000 new messages, with total 2000 so far. Last group took: 10000 millis
which is: 100 messages per second. average: 100"
See Also
•
•
•
•
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
Tracer
How do I use log4j
How do I use Java 1.4 logging
LogEIP for using log directly in the DSL for human logs.
LUCENE (INDEXER AND SEARCH) COMPONENT
Available as of Camel 2.2
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The lucene component is based on the Apache Lucene project. Apache
Lucene is a powerful high-performance, full-featured text search engine
library written entirely in Java. For more details about Lucene, please see the
following links
• http://lucene.apache.org/java/docs/
• http://lucene.apache.org/java/docs/features.html
The lucene component in camel facilitates integration and utilization of
Lucene endpoints in enterprise integration patterns and scenarios. The
lucene component does the following
• builds a searchable index of documents when payloads are sent to
the Lucene Endpoint
• facilitates performing of indexed searches in Camel
This component only supports producer endpoints.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-lucenex.x.x
URI format
lucene:searcherName:insert[?options]
lucene:searcherName:query[?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
Insert Options
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Name
Default
Value
Description
analyzer
StandardAnalyzer
An Analyzer builds TokenStreams, which analyze text. It thus represents a policy for extracting index terms
from text. The value for analyzer can be any class that extends the abstract class
org.apache.lucene.analysis.Analyzer. Lucene also offers a rich set of analyzers out of the box
indexDir
./indexDirectory
A file system directory in which index files are created upon analysis of the document by the specified
analyzer
srcDir
null
An optional directory containing files to be used to be analyzed and added to the index at producer startup.
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Query Options
Name
Default
Value
Description
analyzer
StandardAnalyzer
An Analyzer builds TokenStreams, which analyze text. It thus represents a policy for extracting index terms
from text. The value for analyzer can be any class that extends the abstract class
org.apache.lucene.analysis.Analyzer. Lucene also offers a rich set of analyzers out of the box
indexDir
./indexDirectory
A file system directory in which index files are created upon analysis of the document by the specified
analyzer
maxHits
10
An integer value that limits the result set of the search operation
Sending/Receiving Messages to/from the cache
Message Headers
Header
Description
QUERY
The Lucene Query to performed on the index. The query may include wildcards and phrases
Lucene Producers
This component supports 2 producer endpoints.
• insert - The insert producer builds a searchable index by analyzing
the body in incoming exchanges and associating it with a token
("content").
• query - The query producer performs searches on a pre-created
index. The query uses the searchable index to perform score &
relevance based searches. Queries are sent via the incoming
exchange contains a header property name called 'QUERY'. The value
of the header property 'QUERY' is a Lucene Query. For more details
on how to create Lucene Queries check out http://lucene.apache.org/
java/3_0_0/queryparsersyntax.html
Lucene Processor
There is a processor called LuceneQueryProcessor available to perform
queries against lucene without the need to create a producer.
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Lucene Usage Samples
Example 1: Creating a Lucene index
RouteBuilder builder = new RouteBuilder() {
public void configure() {
from("direct:start").
to("lucene:whitespaceQuotesIndex:insert?
analyzer=#whitespaceAnalyzer&indexDir=#whitespace&srcDir=#load_dir").
to("mock:result");
}
};
Example 2: Loading properties into the JNDI registry in
the Camel Context
@Override
protected JndiRegistry createRegistry() throws Exception {
JndiRegistry registry =
new JndiRegistry(createJndiContext());
registry.bind("whitespace", new File("./whitespaceIndexDir"));
registry.bind("load_dir",
new File("src/test/resources/sources"));
registry.bind("whitespaceAnalyzer",
new WhitespaceAnalyzer());
return registry;
}
...
CamelContext context = new DefaultCamelContext(createRegistry());
Example 2: Performing searches using a Query Producer
RouteBuilder builder = new RouteBuilder() {
public void configure() {
from("direct:start").
setHeader("QUERY", constant("Seinfeld")).
to("lucene:searchIndex:query?
analyzer=#whitespaceAnalyzer&indexDir=#whitespace&maxHits=20").
to("direct:next");
from("direct:next").process(new Processor() {
public void process(Exchange exchange) throws Exception {
Hits hits = exchange.getIn().getBody(Hits.class);
printResults(hits);
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}
private void printResults(Hits hits) {
LOG.debug("Number of hits: " + hits.getNumberOfHits());
for (int i = 0; i < hits.getNumberOfHits(); i++) {
LOG.debug("Hit " + i + " Index Location:" +
hits.getHit().get(i).getHitLocation());
LOG.debug("Hit " + i + " Score:" + hits.getHit().get(i).getScore());
LOG.debug("Hit " + i + " Data:" + hits.getHit().get(i).getData());
}
}
}).to("mock:searchResult");
}
};
Example 3: Performing searches using a Query Processor
RouteBuilder builder = new RouteBuilder() {
public void configure() {
try {
from("direct:start").
setHeader("QUERY", constant("Rodney Dangerfield")).
process(new LuceneQueryProcessor("target/stdindexDir", analyzer,
null, 20)).
to("direct:next");
} catch (Exception e) {
e.printStackTrace();
}
from("direct:next").process(new Processor() {
public void process(Exchange exchange) throws Exception {
Hits hits = exchange.getIn().getBody(Hits.class);
printResults(hits);
}
private void printResults(Hits hits) {
LOG.debug("Number of hits: " + hits.getNumberOfHits());
for (int i = 0; i < hits.getNumberOfHits(); i++) {
LOG.debug("Hit " + i + " Index Location:" +
hits.getHit().get(i).getHitLocation());
LOG.debug("Hit " + i + " Score:" +
hits.getHit().get(i).getScore());
LOG.debug("Hit " + i + " Data:" + hits.getHit().get(i).getData());
}
}
}).to("mock:searchResult");
}
};
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MAIL COMPONENT
The mail component provides access to Email via Spring's Mail support and
the underlying JavaMail system.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-mailx.x.x
URI format
Mail endpoints can have one of the following URI formats (for the protocols,
SMTP, POP3, or IMAP, respectively):
smtp://[username@]host[:port][?options]
pop3://[username@]host[:port][?options]
imap://[username@]host[:port][?options]
The mail component also supports secure variants of these protocols
(layered over SSL). You can enable the secure protocols by adding s to the
scheme:
smtps://[username@]host[:port][?options]
pop3s://[username@]host[:port][?options]
imaps://[username@]host[:port][?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
Sample endpoints
Typically, you specify a URI with login credentials as follows (taking SMTP as
an example):
smtp://[username@]host[:port][?password=somepwd]
Alternatively, it is possible to specify both the user name and the password
as query options:
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Geronimo mail .jar
We have discovered that the geronimo mail .jar (v1.6) has a bug
when polling mails with attachments. It cannot correctly identify the
Content-Type. So, if you attach a .jpeg file to a mail and you poll
it, the Content-Type is resolved as text/plain and not as image/
jpeg. For that reason, we have added an
org.apache.camel.component.ContentTypeResolver SPI
interface which enables you to provide your own implementation
and fix this bug by returning the correct Mime type based on the
file name. So if the file name ends with jpeg/jpg, you can return
image/jpeg.
You can set your custom resolver on the MailComponent instance or on the
MailEndpoint instance. This feature is added in Camel 1.6.2/2.0.
POP3 or IMAP
POP3 has some limitations and end users are encouraged to use
IMAP if possible.
Using mock-mail for testing
You can use a mock framework for unit testing, which allows you to
test without the need for a real mail server. However you should
remember to not include the mock-mail when you go into
production or other environments where you need to send mails to
a real mail server. Just the presence of the mock-javamail.jar on the
classpath means that it will kick in and avoid sending the mails.
smtp://host[:port]?password=somepwd&username=someuser
For example:
smtp://mycompany.mailserver:30?password=tiger&username=scott
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Default ports
As of Camel 1.4, default port numbers are supported. If the port number is
omitted, Camel determines the port number to use based on the protocol.
Protocol
Default Port Number
SMTP
25
SMTPS
465
POP3
110
POP3S
995
IMAP
143
IMAPS
993
Options
Property
Default
host
port
The host name or IP address to connect to.
See DefaultPorts
username
The TCP port number to connect on.
The user name on the email server.
password
null
The password on the email server.
ignoreUriScheme
false
If false, Camel uses the scheme to determine the transport protocol (POP,
IMAP, SMTP etc.)
defaultEncoding
null
The default encoding to use for Mime Messages.
contentType
text/plain
New option in Camel 1.5. The mail message content type. Use text/html for
HTML mails.
folderName
INBOX
The folder to poll.
destination
username@host
@deprecated Use the to option instead. The TO recipients (receivers of the
email).
to
username@host
As of Camel 1.4, the TO recipients (the receivers of the mail). Separate multiple
email addresses with a comma.
CC
null
As of Camel 1.4, the CC recipients (the receivers of the mail). Separate multiple
email addresses with a comma.
BCC
null
As of Camel 1.4, the BCC recipients (the receivers of the mail). Separate
multiple email addresses with a comma.
from
camel@localhost
The FROM email address.
As of Camel 2.3, the Subject of the message being sent. Note: Setting the
subject in the header takes precedence over this option.
subject
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Description
deleteProcessedMessages
true/false
Deletes the messages after they have been processed. This is done by setting
the DELETED flag on the mail message. If false, the SEEN flag is set instead. As
of Camel 1.5, the default setting is false. This option is named delete in
Camel 2.0 onwards.
delete
false
Camel 2.0: Deletes the messages after they have been processed. This is done
by setting the DELETED flag on the mail message. If false, the SEEN flag is set
instead.
processOnlyUnseenMessages
false/true
As of Camel 1.4, it is possible to configure a consumer endpoint so that it
processes only unseen messages (that is, new messages) or all messages. Note
that Camel always skips deleted messages. Setting this option to true will filter
to only unseen messages. As of Camel 1.5, the default setting is true. POP3
does not support the SEEN flag, so this option is not supported in POP3; use IMAP
instead. This option is named unseen in Camel 2.0 onwards.
unseen
true
Camel 2.0: Is used to fetch only unseen messages (that is, new messages).
Note that POP3 does not support the SEEN flag; use IMAP instead.
fetchSize
-1
As of Camel 1.4, this option sets the maximum number of messages to
consume during a poll. This can be used to avoid overloading a mail server, if a
mailbox folder contains a lot of messages. Default value of -1 means no fetch
size and all messages will be consumed. Setting the value to 0 is a special
corner case, where Camel will not consume any messages at all.
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alternateBodyHeader
mail_alternateBody
Camel 1.6.1: Specifies the key to an IN message header that contains an
alternative email body. For example, if you send emails in text/html format and
want to provide an alternative mail body for non-HTML email clients, set the
alternative mail body with this key as a header. In Camel 2.0, this option has
been renamed to alternativeBodyHeader.
alternativeBodyHeader
CamelMailAlternativeBody
Camel 2.0: Specifies the key to an IN message header that contains an
alternative email body. For example, if you send emails in text/html format and
want to provide an alternative mail body for non-HTML email clients, set the
alternative mail body with this key as a header.
debugMode
false
As of Camel 1.4, it is possible to enable debug mode on the underlying mail
framework. The SUN Mail framework logs the debug messages to System.out by
default.
connectionTimeout
30000
As of Camel 1.4, the connection timeout can be configured in milliseconds.
Default is 30 seconds.
consumer.initialDelay
1000
Milliseconds before the polling starts.
consumer.delay
60000
As of Camel 1.4, the default consumer delay is now 60 seconds. Camel will
therefore only poll the mailbox once a minute to avoid overloading the mail
server. The default value in Camel 1.3 is 500 milliseconds.
consumer.useFixedDelay
false
Set to true to use a fixed delay between polls, otherwise fixed rate is used. See
ScheduledExecutorService in JDK for details.
disconnect
false
Camel 2.9: Whether the consumer should disconnect after polling. If enabled
this forces Camel to connect on each poll.
null
As of Camel 2.0, you can set any additional java mail properties. For instance if
you want to set a special property when using POP3 you can now provide the
option directly in the URI such as: mail.pop3.forgettopheaders=true. You can
set multiple such options, for example:
mail.pop3.forgettopheaders=true&mail.mime.encodefilename=true.
mapMailMessage
true
Camel 2.8: Specifies whether Camel should map the received mail message to
Camel body/headers. If set to true, the body of the mail message is mapped to
the body of the Camel IN message and the mail headers are mapped to IN
headers. If this option is set to false then the IN message contains a raw
javax.mail.Message. You can retrieve this raw message by calling
exchange.getIn().getBody(javax.mail.Message.class).
maxMessagesPerPoll
0
Camel 2.0: Specifies the maximum number of messages to gather per poll. By
default, no maximum is set. Can be used to set a limit of e.g. 1000 to avoid
downloading thousands of files when the server starts up. Set a value of 0 or
negative to disable this option.
javaMailSender
null
Camel 2.0: Specifies a pluggable
org.springframework.mail.javamail.JavaMailSender instance in order to
use a custom email implementation. If none provided, Camel uses the default
org.springframework.mail.javamail.JavaMailSenderImpl.
ignoreUnsupportedCharset
false
Camel 2.0: Option to let Camel ignore unsupported charset in the local JVM
when sending mails. If the charset is unsupported then charset=XXX (where XXX
represents the unsupported charset) is removed from the content-type and it
relies on the platform default instead.
mail.XXX
SSL support
The underlying mail framework is responsible for providing SSL support.
Camel uses SUN JavaMail, which only trusts certificates issued by well known
Certificate Authorities. So if you issue your own certificate, you have to
import it into the local Java keystore file (see SSLNOTES.txt in JavaMail for
details).
Defaults changed in Camel 1.4
As of Camel 1.4 the default consumer delay is now 60 seconds. Camel will
therefore only poll the mailbox once a minute to avoid overloading the mail
server. The default value in Camel 1.3 is 500 milliseconds.
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Defaults changed in Camel 1.5
In Camel 1.5 the following default options have changed:
▪ deleteProcessedMessages is now false, as we felt Camel should not
delete mails on the mail server by default.
▪ processOnlyUnseenMessages is now true, as we felt Camel should
only poll new mails by default.
Mail Message Content
Camel uses the message exchange's IN body as the MimeMessage text
content. The body is converted to String.class.
Camel copies all of the exchange's IN headers to the MimeMessage
headers.
The subject of the MimeMessage can be configured using a header
property on the IN message. The code below demonstrates this:
from("direct:a").setHeader("subject",
constant(subject)).to("smtp://james2@localhost");
The same applies for other MimeMessage headers such as recipients, so you
can use a header property as To:
Map map = new HashMap();
map.put("To", "davsclaus@apache.org");
map.put("From", "jstrachan@apache.org");
map.put("Subject", "Camel rocks");
String body = "Hello Claus.\nYes it does.\n\nRegards James.";
template.sendBodyAndHeaders("smtp://davsclaus@apache.org", body, map);
Headers take precedence over pre-configured recipients
From Camel 1.5 onwards, the recipients specified in the message headers
always take precedence over recipients pre-configured in the endpoint URI.
The idea is that if you provide any recipients in the message headers, that is
what you get. The recipients pre-configured in the endpoint URI are treated
as a fallback.
In the sample code below, the email message is sent to
davsclaus@apache.org, because it takes precedence over the preconfigured recipient, info@mycompany.com. Any CC and BCC settings in the
endpoint URI are also ignored and those recipients will not receive any mail.
The choice between headers and pre-configured settings is all or nothing: the
mail component either takes the recipients exclusively from the headers or
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exclusively from the pre-configured settings. It is not possible to mix and
match headers and pre-configured settings.
Map headers = new HashMap();
headers.put("to", "davsclaus@apache.org");
template.sendBodyAndHeaders("smtp://admin@localhost?to=info@mycompany.com",
"Hello World", headers);
Multiple recipients for easier configuration
As of Camel 1.5, it is possible to set multiple recipients using a commaseparated or a semicolon-separated list. This applies both to header settings
and to settings in an endpoint URI. For example:
Map headers = new HashMap();
headers.put("to", "davsclaus@apache.org ; jstrachan@apache.org ;
ningjiang@apache.org");
The preceding example uses a semicolon, ;, as the separator character.
Setting sender name and email
You can specify recipients in the format, name , to include both the
name and the email address of the recipient.
For example, you define the following headers on the a Message:
Map headers = new HashMap();
map.put("To", "Claus Ibsen ");
map.put("From", "James Strachan ");
map.put("Subject", "Camel is cool");
SUN JavaMail
SUN JavaMail is used under the hood for consuming and producing mails.
We encourage end-users to consult these references when using either POP3
or IMAP protocol. Note particularly that POP3 has a much more limited set of
features than IMAP.
▪ SUN POP3 API
▪ SUN IMAP API
▪ And generally about the MAIL Flags
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Samples
We start with a simple route that sends the messages received from a JMS
queue as emails. The email account is the admin account on
mymailserver.com.
from("jms://queue:subscription").to("smtp://admin@mymailserver.com?password=secret");
In the next sample, we poll a mailbox for new emails once every minute.
Notice that we use the special consumer option for setting the poll interval,
consumer.delay, as 60000 milliseconds = 60 seconds.
from("imap://admin@mymailserver.com
password=secret&unseen=true&consumer.delay=60000")
.to("seda://mails");
In this sample we want to send a mail to multiple recipients. This feature was
introduced in camel 1.4:
// all the recipients of this mail are:
// To: camel@riders.org , easy@riders.org
// CC: me@you.org
// BCC: someone@somewhere.org
String recipients =
"&To=camel@riders.org,easy@riders.org&CC=me@you.org&BCC=someone@somewhere.org";
from("direct:a").to("smtp://you@mymailserver.com?password=secret&From=you@apache.org"
+ recipients);
Sending mail with attachment sample
The mail component supports attachments, which is a feature that was
introduced in Camel 1.4. In the sample below, we send a mail message
containing a plain text message with a logo file attachment.
// create an exchange with a normal body and attachment to be produced as email
Endpoint endpoint =
context.getEndpoint("smtp://james@mymailserver.com?password=secret");
// create the exchange with the mail message that is multipart with a file and a
Hello World text/plain message.
Exchange exchange = endpoint.createExchange();
Message in = exchange.getIn();
in.setBody("Hello World");
in.addAttachment("logo.jpeg", new DataHandler(new FileDataSource("src/test/data/
logo.jpeg")));
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Attachments are not support by all Camel components
The Attachments API is based on the Java Activation Framework and
is generally only used by the Mail API. Since many of the other
Camel components do not support attachments, the attachments
could potentially be lost as they propagate along the route. The rule
of thumb, therefore, is to add attachments just before sending a
message to the mail endpoint.
// create a producer that can produce the exchange (= send the mail)
Producer producer = endpoint.createProducer();
// start the producer
producer.start();
// and let it go (processes the exchange by sending the email)
producer.process(exchange);
SSL sample
In this sample, we want to poll our Google mail inbox for mails. To download
mail onto a local mail client, Google mail requires you to enable and
configure SSL. This is done by logging into your Google mail account and
changing your settings to allow IMAP access. Google have extensive
documentation on how to do this.
from("imaps://imap.gmail.com?username=YOUR_USERNAME@gmail.com&password=YOUR_PASSWORD"
+ "&delete=false&unseen=true&consumer.delay=60000").to("log:newmail");
The preceding route polls the Google mail inbox for new mails once every
minute and logs the received messages to the newmail logger category.
Running the sample with DEBUG logging enabled, we can monitor the
progress in the logs:
2008-05-08 06:32:09,640 DEBUG MailConsumer - Connecting to MailStore
imaps//imap.gmail.com:993 (SSL enabled), folder=INBOX
2008-05-08 06:32:11,203 DEBUG MailConsumer - Polling mailfolder:
imaps//imap.gmail.com:993 (SSL enabled), folder=INBOX
2008-05-08 06:32:11,640 DEBUG MailConsumer - Fetching 1 messages. Total 1 messages.
2008-05-08 06:32:12,171 DEBUG MailConsumer - Processing message: messageNumber=[332],
from=[James Bond <007@mi5.co.uk>], to=YOUR_USERNAME@gmail.com], subject=[...
2008-05-08 06:32:12,187 INFO newmail - Exchange[MailMessage: messageNumber=[332],
from=[James Bond <007@mi5.co.uk>], to=YOUR_USERNAME@gmail.com], subject=[...
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Consuming mails with attachment sample
In this sample we poll a mailbox and store all attachments from the mails as
files. First, we define a route to poll the mailbox. As this sample is based on
google mail, it uses the same route as shown in the SSL sample:
from("imaps://imap.gmail.com?username=YOUR_USERNAME@gmail.com&password=YOUR_PASSWORD"
+ "&delete=false&unseen=true&consumer.delay=60000").process(new
MyMailProcessor());
Instead of logging the mail we use a processor where we can process the
mail from java code:
public void process(Exchange exchange) throws Exception {
// the API is a bit clunky so we need to loop
Map attachments = exchange.getIn().getAttachments();
if (attachments.size() > 0) {
for (String name : attachments.keySet()) {
DataHandler dh = attachments.get(name);
// get the file name
String filename = dh.getName();
// get the content and convert it to byte[]
byte[] data = exchange.getContext().getTypeConverter()
.convertTo(byte[].class, dh.getInputStream());
// write the data to a file
FileOutputStream out = new FileOutputStream(filename);
out.write(data);
out.flush();
out.close();
}
}
}
As you can see the API to handle attachments is a bit clunky but it's there so
you can get the javax.activation.DataHandler so you can handle the
attachments using standard API.
See Also
•
•
•
•
801
Configuring Camel
Component
Endpoint
Getting Started
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
MINA COMPONENT
The mina: component is a transport for working with Apache MINA
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-minax.x.x
URI format
mina:tcp://hostname[:port][?options]
mina:udp://hostname[:port][?options]
mina:vm://hostname[:port][?options]
From Camel 1.3 onwards you can specify a codec in the Registry using the
codec option. If you are using TCP and no codec is specified then the
textline flag is used to determine if text line based codec or object
serialization should be used instead. By default the object serialization is
used.
For UDP if no codec is specified the default uses a basic ByteBuffer based
codec.
The VM protocol is used as a direct forwarding mechanism in the same
JVM. See the MINA VM-Pipe API documentation for details.
A Mina producer has a default timeout value of 30 seconds, while it waits
for a response from the remote server.
In normal use, camel-mina only supports marshalling the body
content—message headers and exchange properties are not sent.
However, the option, transferExchange, does allow you to transfer the
exchange itself over the wire. See options below.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Option
Default
Value
Description
codec
null
As of 1.3, you can refer to a named ProtocolCodecFactory instance in your Registry such as your
Spring ApplicationContext, which is then used for the marshalling.
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codec
null
Camel 2.0: You must use the # notation to look up your codec in the Registry. For example, use
#myCodec to look up a bean with the id value, myCodec.
disconnect
false
Camel 2.3: Whether or not to disconnect(close) from Mina session right after use. Can be used for
both consumer and producer.
textline
false
Only used for TCP. If no codec is specified, you can use this flag in 1.3 or later to indicate a text line
based codec; if not specified or the value is false, then Object Serialization is assumed over TCP.
textlineDelimiter
DEFAULT
Camel 1.6.0/2.0 Only used for TCP and if textline=true. Sets the text line delimiter to use. Possible
values are: DEFAULT, AUTO, WINDOWS, UNIX or MAC. If none provided, Camel will use DEFAULT. This
delimiter is used to mark the end of text.
sync
false/true
As of 1.3, you can configure the exchange pattern to be either InOnly (default) or InOut. Setting
sync=true means a synchronous exchange (InOut), where the client can read the response from
MINA (the exchange Out message). The default value has changed in Camel 1.5 to true. In older
releases, the default value is false.
lazySessionCreation
See
description
As of 1.3, sessions can be lazily created to avoid exceptions, if the remote server is not up and
running when the Camel producer is started. From Camel 2.0 onwards, the default is true. In Camel
1.x, the default is false.
timeout
30000
As of 1.3, you can configure the timeout that specifies how long to wait for a response from a remote
server. The timeout unit is in milliseconds, so 60000 is 60 seconds. The timeout is only used for Mina
producer.
encoding
JVM Default
As of 1.3, you can configure the encoding (a charset name) to use for the TCP textline codec and the
UDP protocol. If not provided, Camel will use the JVM default Charset.
transferExchange
false
Only used for TCP. As of 1.3, you can transfer the exchange over the wire instead of just the body.
The following fields are transferred: In body, Out body, fault body, In headers, Out headers, fault
headers, exchange properties, exchange exception. This requires that the objects are serializable.
Camel will exclude any non-serializable objects and log it at WARN level.
minaLogger
false
As of 1.3, you can enable the Apache MINA logging filter. Apache MINA uses slf4j logging at INFO
level to log all input and output.
filters
null
As of 2.0, you can set a list of Mina IoFilters to register. The filters value must be one of the
following:
•
Camel 2.2: comma-separated list of bean references (e.g.
#filterBean1,#filterBean2) where each bean must be of type
org.apache.mina.common.IoFilter.
•
Camel 2.0: a reference to a bean of type
List.
encoderMaxLineLength
-1
As of 2.1, you can set the textline protocol encoder max line length. By default the default value of
Mina itself is used which are Integer.MAX_VALUE.
decoderMaxLineLength
-1
As of 2.1, you can set the textline protocol decoder max line length. By default the default value of
Mina itself is used which are 1024.
producerPoolSize
16
1.6.2 (only in 1.6.x): The TCP producer is now thread safe and supports concurrency much better.
This option allows you to configure the number of threads in its thread pool for concurrent producers.
Note: Camel 2.0 have a pooled service which ensured it was already thread safe and supported
concurrency already. So this is a special patch for 1.6.x.
allowDefaultCodec
true
The mina component installs a default codec if both, codec is null and textline is false. Setting
allowDefaultCodec to false prevents the mina component from installing a default codec as the
first element in the filter chain. This is useful in scenarios where another filter must be the first in the
filter chain, like the SSL filter.
disconnectOnNoReply
true
Camel 2.3: If sync is enabled then this option dictates MinaConsumer if it should disconnect where
there is no reply to send back.
noReplyLogLevel
WARN
Camel 2.3: If sync is enabled this option dictates MinaConsumer which logging level to use when
logging a there is no reply to send back. Values are: FATAL, ERROR, INFO, DEBUG, OFF.
Default behavior changed
In Camel 2.0 the codec option must use # notation for lookup of the codec
bean in the Registry.
In Camel 2.0 the lazySessionCreation option now defaults to true.
In Camel 1.5 the sync option has changed its default value from false to
true, as we felt it was confusing for end-users when they used MINA to call
remote servers and Camel wouldn't wait for the response.
In Camel 1.4 or later codec=textline is no longer supported. Use the
textline=true option instead.
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Using a custom codec
See the Mina documentation how to write your own codec. To use your
custom codec with camel-mina, you should register your codec in the
Registry; for example, by creating a bean in the Spring XML file. Then use the
codec option to specify the bean ID of your codec. See HL7 that has a
custom codec.
Sample with sync=false
In this sample, Camel exposes a service that listens for TCP connections on
port 6200. We use the textline codec. In our route, we create a Mina
consumer endpoint that listens on port 6200:
from("mina:tcp://localhost:" + port1 + "?textline=true&sync=false").to("mock:result");
As the sample is part of a unit test, we test it by sending some data to it on
port 6200.
MockEndpoint mock = getMockEndpoint("mock:result");
mock.expectedBodiesReceived("Hello World");
template.sendBody("mina:tcp://localhost:" + port1 + "?textline=true&sync=false",
"Hello World");
assertMockEndpointsSatisfied();
Sample with sync=true
In the next sample, we have a more common use case where we expose a
TCP service on port 6201 also use the textline codec. However, this time we
want to return a response, so we set the sync option to true on the
consumer.
from("mina:tcp://localhost:" + port2 + "?textline=true&sync=true").process(new
Processor() {
public void process(Exchange exchange) throws Exception {
String body = exchange.getIn().getBody(String.class);
exchange.getOut().setBody("Bye " + body);
}
});
Then we test the sample by sending some data and retrieving the response
using the template.requestBody() method. As we know the response is a
String, we cast it to String and can assert that the response is, in fact,
something we have dynamically set in our processor code logic.
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String response = (String)template.requestBody("mina:tcp://localhost:" + port2 +
"?textline=true&sync=true", "World");
assertEquals("Bye World", response);
Sample with Spring DSL
Spring DSL can, of course, also be used for MINA. In the sample below we
expose a TCP server on port 5555:
In the route above, we expose a TCP server on port 5555 using the textline
codec. We let the Spring bean with ID, myTCPOrderHandler, handle the
request and return a reply. For instance, the handler bean could be
implemented as follows:
public String handleOrder(String payload) {
...
return "Order: OK"
}
Configuring Mina endpoints using Spring bean style
Available as of Camel 2.0
Configuration of Mina endpoints is now possible using regular Spring bean
style configuration in the Spring DSL.
However, in the underlying Apache Mina toolkit, it is relatively difficult to
set up the acceptor and the connector, because you can not use simple
setters. To resolve this difficulty, we leverage the MinaComponent as a Spring
factory bean to configure this for us. If you really need to configure this
yourself, there are setters on the MinaEndpoint to set these when needed.
The sample below shows the factory approach:
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And then we can refer to our endpoint directly in the route, as follows:
Closing Session When Complete
Available as of Camel 1.6.1
When acting as a server you sometimes want to close the session when,
for example, a client conversion is finished. To instruct Camel to close the
session, you should add a header with the key
CamelMinaCloseSessionWhenComplete set to a boolean true value.
For instance, the example below will close the session after it has written
the bye message back to the client:
from("mina:tcp://localhost:8080?sync=true&textline=true").process(new
Processor() {
public void process(Exchange exchange) throws Exception {
String body = exchange.getIn().getBody(String.class);
exchange.getOut().setBody("Bye " + body);
exchange.getOut().setHeader(MinaConstants.MINA_CLOSE_SESSION_WHEN_COMPLETE, true);
}
});
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Get the IoSession for message
Available since Camel 2.1
You can get the IoSession from the message header with this key
MinaEndpoint.HEADER_MINA_IOSESSION, and also get the local host address
with the key MinaEndpoint.HEADER_LOCAL_ADDRESS and remote host
address with the key MinaEndpoint.HEADER_REMOTE_ADDRESS.
Configuring Mina filters
Available since Camel 2.0
Filters permit you to use some Mina Filters, such as SslFilter. You can
also implement some customized filters. Please note that codec and logger
are also implemented as Mina filters of type, IoFilter. Any filters you may
define are appended to the end of the filter chain; that is, after codec and
logger.
For instance, the example below will send a keep-alive message after 10
seconds of inactivity:
public class KeepAliveFilter extends IoFilterAdapter {
@Override
public void sessionCreated(NextFilter nextFilter, IoSession session)
throws Exception {
session.setIdleTime(IdleStatus.BOTH_IDLE, 10);
nextFilter.sessionCreated(session);
}
@Override
public void sessionIdle(NextFilter nextFilter, IoSession session,
IdleStatus status) throws Exception {
session.write("NOOP"); // NOOP is a FTP command for keep alive
nextFilter.sessionIdle(session, status);
}
}
As Camel Mina may use a request-reply scheme, the endpoint as a client
would like to drop some message, such as greeting when the connection is
established. For example, when you connect to an FTP server, you will get a
220 message with a greeting (220 Welcome to Pure-FTPd). If you don't drop
the message, your request-reply scheme will be broken.
public class DropGreetingFilter extends IoFilterAdapter {
@Override
public void messageReceived(NextFilter nextFilter, IoSession session,
Object message) throws Exception {
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CH AP T E R 11 - C OM P ON E N T A P P E N DIX
if (message instanceof String) {
String ftpMessage = (String) message;
// "220" is given as greeting. "200 Zzz" is given as a response to "NOOP"
(keep alive)
if (ftpMessage.startsWith("220") || or ftpMessage.startsWith("200 Zzz")) {
// Dropping greeting
return;
}
}
nextFilter.messageReceived(session, message);
}
}
Then, you can configure your endpoint using Spring DSL:
See Also
•
•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
Camel Netty
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MOCK COMPONENT
Testing of distributed and asynchronous processing is notoriously difficult.
The Mock, Test and DataSet endpoints work great with the Camel Testing
Framework to simplify your unit and integration testing using Enterprise
Integration Patterns and Camel's large range of Components together with
the powerful Bean Integration.
The Mock component provides a powerful declarative testing mechanism,
which is similar to jMock in that it allows declarative expectations to be
created on any Mock endpoint before a test begins. Then the test is run,
which typically fires messages to one or more endpoints, and finally the
expectations can be asserted in a test case to ensure the system worked as
expected.
This allows you to test various things like:
• The correct number of messages are received on each endpoint,
• The correct payloads are received, in the right order,
• Messages arrive on an endpoint in order, using some Expression to
create an order testing function,
• Messages arrive match some kind of Predicate such as that specific
headers have certain values, or that parts of the messages match
some predicate, such as by evaluating an XPath or XQuery
Expression.
Note that there is also the Test endpoint which is a Mock endpoint, but which
uses a second endpoint to provide the list of expected message bodies and
automatically sets up the Mock endpoint assertions. In other words, it's a
Mock endpoint that automatically sets up its assertions from some sample
messages in a File or database, for example.
URI format
mock:someName[?options]
Where someName can be any string that uniquely identifies the endpoint.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
809
Option
Default
Description
reportGroup
null
A size to use a throughput logger for reporting
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
Simple Example
Here's a simple example of Mock endpoint in use. First, the endpoint is
resolved on the context. Then we set an expectation, and then, after the test
has run, we assert that our expectations have been met.
MockEndpoint resultEndpoint = context.resolveEndpoint("mock:foo", MockEndpoint.class);
resultEndpoint.expectedMessageCount(2);
// send some messages
...
// now lets assert that the mock:foo endpoint received 2 messages
resultEndpoint.assertIsSatisfied();
You typically always call the assertIsSatisfied() method to test that the
expectations were met after running a test.
Camel will by default wait 10 seconds when the assertIsSatisfied() is
invoked. This can be configured by setting the setResultWaitTime(millis)
method.
When the assertion is satisfied then Camel will stop waiting and continue
from the assertIsSatisfied method. That means if a new message arrives
on the mock endpoint, just a bit later, that arrival will not affect the outcome
of the assertion. Suppose you do want to test that no new messages arrives
after a period thereafter, then you can do that by setting the
setAssertPeriod method.
Using assertPeriod
Available as of Camel 2.7
When the assertion is satisfied then Camel will stop waiting and continue
from the assertIsSatisfied method. That means if a new message arrives
on the mock endpoint, just a bit later, that arrival will not affect the outcome
of the assertion. Suppose you do want to test that no new messages arrives
after a period thereafter, then you can do that by setting the
setAssertPeriod method, for example:
MockEndpoint resultEndpoint = context.resolveEndpoint("mock:foo", MockEndpoint.class);
resultEndpoint.setAssertPeriod(5000);
resultEndpoint.expectedMessageCount(2);
// send some messages
...
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// now lets assert that the mock:foo endpoint received 2 messages
resultEndpoint.assertIsSatisfied();
Setting expectations
You can see from the javadoc of MockEndpoint the various helper methods
you can use to set expectations. The main methods are as follows:
Method
Description
expectedMessageCount(int)
To define the expected message count on the endpoint.
expectedMinimumMessageCount(int)
To define the minimum number of expected messages on the endpoint.
expectedBodiesReceived(...)
To define the expected bodies that should be received (in order).
expectedHeaderReceived(...)
To define the expected header that should be received
expectsAscending(Expression)
To add an expectation that messages are received in order, using the given Expression to compare
messages.
expectsDescending(Expression)
To add an expectation that messages are received in order, using the given Expression to compare
messages.
expectsNoDuplicates(Expression)
To add an expectation that no duplicate messages are received; using an Expression to calculate a
unique identifier for each message. This could be something like the JMSMessageID if using JMS, or some
unique reference number within the message.
Here's another example:
resultEndpoint.expectedBodiesReceived("firstMessageBody", "secondMessageBody",
"thirdMessageBody");
Adding expectations to specific messages
In addition, you can use the message(int messageIndex) method to add
assertions about a specific message that is received.
For example, to add expectations of the headers or body of the first
message (using zero-based indexing like java.util.List), you can use the
following code:
resultEndpoint.message(0).header("foo").isEqualTo("bar");
There are some examples of the Mock endpoint in use in the camel-core
processor tests.
Mocking existing endpoints
Available as of Camel 2.7
Camel now allows you to automatic mock existing endpoints in your Camel
routes.
Suppose you have the given route below:
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How it works
Important: The endpoints are still in action, what happens is that a
Mock endpoint is injected and receives the message first, it then
delegate the message to the target endpoint. You can view this as a
kind of intercept and delegate or endpoint listener.
Listing 79. Route
@Override
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
from("direct:start").to("direct:foo").to("log:foo").to("mock:result");
from("direct:foo").transform(constant("Bye World"));
}
};
}
You can then use the adviceWith feature in Camel to mock all the endpoints
in a given route from your unit test, as shown below:
Listing 80. adviceWith mocking all endpoints
public void testAdvisedMockEndpoints() throws Exception {
// advice the first route using the inlined AdviceWith route builder
// which has extended capabilities than the regular route builder
context.getRouteDefinitions().get(0).adviceWith(context, new
AdviceWithRouteBuilder() {
@Override
public void configure() throws Exception {
// mock all endpoints
mockEndpoints();
}
});
getMockEndpoint("mock:direct:start").expectedBodiesReceived("Hello World");
getMockEndpoint("mock:direct:foo").expectedBodiesReceived("Hello World");
getMockEndpoint("mock:log:foo").expectedBodiesReceived("Bye World");
getMockEndpoint("mock:result").expectedBodiesReceived("Bye World");
template.sendBody("direct:start", "Hello World");
assertMockEndpointsSatisfied();
// additional test to ensure correct endpoints in registry
assertNotNull(context.hasEndpoint("direct:start"));
assertNotNull(context.hasEndpoint("direct:foo"));
assertNotNull(context.hasEndpoint("log:foo"));
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assertNotNull(context.hasEndpoint("mock:result"));
// all the endpoints was mocked
assertNotNull(context.hasEndpoint("mock:direct:start"));
assertNotNull(context.hasEndpoint("mock:direct:foo"));
assertNotNull(context.hasEndpoint("mock:log:foo"));
}
Notice that the mock endpoints is given the uri mock:, for
example mock:direct:foo. Camel logs at INFO level the endpoints being
mocked:
INFO
Adviced endpoint [direct://foo] with mock endpoint [mock:direct:foo]
Its also possible to only mock certain endpoints using a pattern. For example
to mock all log endpoints you do as shown:
Listing 81. adviceWith mocking only log endpoints using a pattern
public void testAdvisedMockEndpointsWithPattern() throws Exception {
// advice the first route using the inlined AdviceWith route builder
// which has extended capabilities than the regular route builder
context.getRouteDefinitions().get(0).adviceWith(context, new
AdviceWithRouteBuilder() {
@Override
public void configure() throws Exception {
// mock only log endpoints
mockEndpoints("log*");
}
});
// now we can refer to log:foo as a mock and set our expectations
getMockEndpoint("mock:log:foo").expectedBodiesReceived("Bye World");
getMockEndpoint("mock:result").expectedBodiesReceived("Bye World");
template.sendBody("direct:start", "Hello World");
assertMockEndpointsSatisfied();
// additional test to ensure correct endpoints in registry
assertNotNull(context.hasEndpoint("direct:start"));
assertNotNull(context.hasEndpoint("direct:foo"));
assertNotNull(context.hasEndpoint("log:foo"));
assertNotNull(context.hasEndpoint("mock:result"));
// only the log:foo endpoint was mocked
assertNotNull(context.hasEndpoint("mock:log:foo"));
assertNull(context.hasEndpoint("mock:direct:start"));
assertNull(context.hasEndpoint("mock:direct:foo"));
}
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Mocked endpoints are without parameters
Endpoints which are mocked will have their parameters stripped off.
For example the endpoint "log:foo?showAll=true" will be mocked to
the following endpoint "mock:log:foo". Notice the parameters has
been removed.
The pattern supported can be a wildcard or a regular expression. See more
details about this at Intercept as its the same matching function used by
Camel.
Mocking existing endpoints using the camel-test
component
Instead of using the adviceWith to instruct Camel to mock endpoints, you
can easily enable this behavior when using the camel-test Test Kit.
The same route can be tested as follows. Notice that we return "*" from the
isMockEndpoints method, which tells Camel to mock all endpoints.
If you only want to mock all log endpoints you can return "log*" instead.
Listing 82. isMockEndpoints using camel-test kit
public class IsMockEndpointsJUnit4Test extends CamelTestSupport {
@Override
public String isMockEndpoints() {
// override this method and return the pattern for which endpoints to mock.
// use * to indicate all
return "*";
}
@Test
public void testMockAllEndpoints() throws Exception {
// notice we have automatic mocked all endpoints and the name of the
endpoints is "mock:uri"
getMockEndpoint("mock:direct:start").expectedBodiesReceived("Hello World");
getMockEndpoint("mock:direct:foo").expectedBodiesReceived("Hello World");
getMockEndpoint("mock:log:foo").expectedBodiesReceived("Bye World");
getMockEndpoint("mock:result").expectedBodiesReceived("Bye World");
template.sendBody("direct:start", "Hello World");
assertMockEndpointsSatisfied();
// additional test to ensure correct endpoints in registry
assertNotNull(context.hasEndpoint("direct:start"));
assertNotNull(context.hasEndpoint("direct:foo"));
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Mind that mocking endpoints causes the messages to be copied
when they arrive on the mock.
That means Camel will use more memory. This may not be suitable
when you send in a lot of messages.
assertNotNull(context.hasEndpoint("log:foo"));
assertNotNull(context.hasEndpoint("mock:result"));
// all the endpoints was mocked
assertNotNull(context.hasEndpoint("mock:direct:start"));
assertNotNull(context.hasEndpoint("mock:direct:foo"));
assertNotNull(context.hasEndpoint("mock:log:foo"));
}
@Override
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
from("direct:start").to("direct:foo").to("log:foo").to("mock:result");
from("direct:foo").transform(constant("Bye World"));
}
};
}
}
Mocking existing endpoints with XML DSL
If you do not use the camel-test component for unit testing (as shown
above) you can use a different approach when using XML files for routes.
The solution is to create a new XML file used by the unit test and then
include the intended XML file which has the route you want to test.
Suppose we have the route in the camel-route.xml file:
Listing 83. camel-route.xml
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Bye World
Then we create a new XML file as follows, where we include the camelroute.xml file and define a spring bean with the class
org.apache.camel.impl.InterceptSendToMockEndpointStrategy which
tells Camel to mock all endpoints:
Listing 84. test-camel-route.xml
Then in your unit test you load the new XML file (test-camel-route.xml)
instead of camel-route.xml.
To only mock all Log endpoints you can define the pattern in the
constructor for the bean:
Testing with arrival times
Available as of Camel 2.7
The Mock endpoint stores the arrival time of the message as a property on
the Exchange.
Date time = exchange.getProperty(Exchange.RECEIVED_TIMESTAMP, Date.class);
You can use this information to know when the message arrived on the mock.
But it also provides foundation to know the time interval between the
previous and next message arrived on the mock. You can use this to set
expectations using the arrives DSL on the Mock endpoint.
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For example to say that the first message should arrive between 0-2
seconds before the next you can do:
mock.message(0).arrives().noLaterThan(2).seconds().beforeNext();
You can also define this as that 2nd message (0 index based) should arrive
no later than 0-2 seconds after the previous:
mock.message(1).arrives().noLaterThan(2).seconds().afterPrevious();
You can also use between to set a lower bound. For example suppose that it
should be between 1-4 seconds:
mock.message(1).arrives().between(1, 4).seconds().afterPrevious();
You can also set the expectation on all messages, for example to say that the
gap between them should be at most 1 second:
mock.allMessages().arrives().noLaterThan(1).seconds().beforeNext();
See Also
•
•
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
Spring Testing
Testing
MSV COMPONENT
The MSV component performs XML validation of the message body using the
MSV Library and any of the supported XML schema languages, such as XML
Schema or RelaxNG XML Syntax.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-msvx.x.x
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time units
In the example above we use seconds as the time unit, but Camel
offers milliseconds, and minutes as well.
Note that the Jing component also supports RelaxNG Compact Syntax
URI format
msv:someLocalOrRemoteResource[?options]
Where someLocalOrRemoteResource is some URL to a local resource on
the classpath or a full URL to a remote resource or resource on the file
system. For example
msv:org/foo/bar.rng
msv:file:../foo/bar.rng
msv:http://acme.com/cheese.rng
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Option
Default
Description
useDom
true
Camel 2.0: Whether DOMSource/DOMResult or SaxSource/SaxResult should be used by the validator. Note:
DOM must be used by the MSV component.
Example
The following example shows how to configure a route from endpoint
direct:start which then goes to one of two endpoints, either mock:valid or
mock:invalid based on whether or not the XML matches the given RelaxNG
XML Schema (which is supplied on the classpath).
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org.apache.camel.ValidationException
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
MYBATIS
Available as of Camel 2.7
The mybatis: component allows you to query, poll, insert, update and
delete data in a relational database using MyBatis.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-mybatisx.x.x
URI format
mybatis:statementName[?options]
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Where statementName is the statement name in the MyBatis XML mapping
file which maps to the query, insert, update or delete operation you wish to
evaluate.
You can append query options to the URI in the following format,
?option=value&option=value&...
This component will by default load the MyBatis SqlMapConfig file from the
root of the classpath and expected named as SqlMapConfig.xml.
If the file is located in another location, you would have to configure the
configurationUri option on the MyBatisComponent component.
Options
Option
Type
Default
Description
consumer.onConsume
String
null
Statements to run after consuming. Can be used, for example, to update
rows after they have been consumed and processed in Camel. See
sample later. Multiple statements can be separated with comma.
consumer.useIterator
boolean
true
If true each row returned when polling will be processed individually. If
false the entire List of data is set as the IN body.
consumer.routeEmptyResultSet
boolean
false
Sets whether empty result set should be routed or not. By default, empty
result sets are not routed.
statementType
StatementType
null
Mandatory to specify for producer to control which kind of operation to
invoke. The enum values are: SelectOne, SelectList, Insert, Update,
Delete.
maxMessagesPerPoll
int
0
An integer to define a maximum messages to gather per poll. By default,
no maximum is set. Can be used to set a limit of e.g. 1000 to avoid when
starting up the server that there are thousands of files. Set a value of 0 or
negative to disabled it.
Message Headers
Camel will populate the result message, either IN or OUT with a header with
the statement used:
Header
Type
Description
CamelMyBatisStatementName
String
The statementName used (for example: insertAccount).
CamelMyBatisResult
Object
The response returned from MtBatis in any of the operations. For instance an INSERT could return
the auto-generated key, or number of rows etc.
Message Body
The response from MyBatis will only be set as body if it's a SELECT
statement. That means, for example, for INSERT statements Camel will not
replace the body. This allows you to continue routing and keep the original
body. The response from MyBatis is always stored in the header with the key
CamelMyBatisResult.
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Samples
For example if you wish to consume beans from a JMS queue and insert them
into a database you could do the following:
from("activemq:queue:newAccount").
to("mybatis:insertAccount?statementType=Insert");
Notice we have to specify the statementType, as we need to instruct Camel
which kind of operation to invoke.
Where insertAccount is the MyBatis ID in the SQL mapping file:
insert into ACCOUNT (
ACC_ID,
ACC_FIRST_NAME,
ACC_LAST_NAME,
ACC_EMAIL
)
values (
#{id}, #{firstName}, #{lastName}, #{emailAddress}
)
Using StatementType for better control of MyBatis
When routing to an MyBatis endpoint you want more fine grained control so
you can control whether the SQL statement to be executed is a SELEECT,
UPDATE, DELETE or INSERT etc. So for instance if we want to route to an
MyBatis endpoint in which the IN body contains parameters to a SELECT
statement we can do:
from("direct:start")
.to("mybatis:selectAccountById?statementType=SelectOne")
.to("mock:result");
In the code above we can invoke the MyBatis statement selectAccountById
and the IN body should contain the account id we want to retrieve, such as
an Integer type.
We can do the same for some of the other operations, such as
SelectList:
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from("direct:start")
.to("mybatis:selectAllAccounts?statementType=SelectList")
.to("mock:result");
And the same for UPDATE, where we can send an Account object as IN body
to MyBatis:
from("direct:start")
.to("mybatis:updateAccount?statementType=Update")
.to("mock:result");
Scheduled polling example
Since this component does not support scheduled polling, you need to use
another mechanism for triggering the scheduled polls, such as the Timer or
Quartz components.
In the sample below we poll the database, every 30 seconds using the
Timer component and send the data to the JMS queue:
from("timer://pollTheDatabase?delay=30000").to("mbatis:selectAllAccounts").to("activemq:queue:allAccou
And the MyBatis SQL mapping file used:
Using onConsume
This component supports executing statements after data have been
consumed and processed by Camel. This allows you to do post updates in the
database. Notice all statements must be UPDATE statements. Camel supports
executing multiple statements whose name should be separated by comma.
The route below illustrates we execute the consumeAccount statement
data is processed. This allows us to change the status of the row in the
database to processed, so we avoid consuming it twice or more.
from("mybatis:selectUnprocessedAccounts?consumer.onConsume=consumeAccount").to("mock:results");
And the statements in the sqlmap file:
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update ACCOUNT set PROCESSED = true where ACC_ID = #{id}
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
NAGIOS
Available as of Camel 2.3
The Nagios component allows you to send passive checks to Nagios.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-nagiosx.x.x
URI format
nagios://host[:port][?Options]
Camel provides two abilities with the Nagios component. You can send
passive check messages by sending a message to its endpoint.
Camel also provides a EventNotifer which allows you to send notifications to
Nagios.
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Options
Name
Default
Value
Description
host
none
This is the address of the Nagios host where checks should be send.
port
The port number of the host.
password
Password to be authenticated when sending checks to Nagios.
connectionTimeout
5000
Connection timeout in millis.
timeout
5000
Sending timeout in millis.
To use an already configured com.googlecode.jsendnsca.core.NagiosSettings object. Then any of
the other options are not in use, if using this.
nagiosSettings
sendSync
true
Whether or not to use synchronous when sending a passive check. Setting it to false will allow Camel to
continue routing the message and the passive check message will be send asynchronously.
encryptionMethod
No
Camel 2.9: To specify an encryption method. Possible values: No, Xor, or TripleDes.
Headers
Name
Description
CamelNagiosHostName
This is the address of the Nagios host where checks should be send. This header will override any existing
hostname configured on the endpoint.
CamelNagiosLevel
This is the severity level. You can use values CRITICAL, WARNING, OK. Camel will by default use OK.
CamelNagiosServiceName
The servie name. Will default use the CamelContext name.
Sending message examples
You can send a message to Nagios where the message payload contains the
message. By default it will be OK level and use the CamelContext name as
the service name. You can overrule these values using headers as shown
above.
For example we send the Hello Nagios message to Nagios as follows:
template.sendBody("direct:start", "Hello Nagios");
from("direct:start").to("nagios:127.0.0.1:5667?password=secret").to("mock:result");
To send a CRITICAL message you can send the headers such as:
Map headers = new HashMap();
headers.put(NagiosConstants.LEVEL, "CRITICAL");
headers.put(NagiosConstants.HOST_NAME, "myHost");
headers.put(NagiosConstants.SERVICE_NAME, "myService");
template.sendBodyAndHeaders("direct:start", "Hello Nagios", headers);
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Using NagiosEventNotifer
The Nagios component also provides an EventNotifer which you can use to
send events to Nagios. For example we can enable this from Java as follows:
NagiosEventNotifier notifier = new NagiosEventNotifier();
notifier.getConfiguration().setHost("localhost");
notifier.getConfiguration().setPort(5667);
notifier.getConfiguration().setPassword("password");
CamelContext context = ...
context.getManagementStrategy().addEventNotifier(notifier);
return context;
In Spring XML its just a matter of defining a Spring bean with the type
EventNotifier and Camel will pick it up as documented here: Advanced
configuration of CamelContext using Spring.
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
NETTY COMPONENT
Available as of Camel 2.3
The netty component in Camel is a socket communication component,
based on the JBoss Netty community offering (available under an Apache 2.0
license).
Netty is a NIO client server framework which enables quick and easy
development of network applications such as protocol servers and clients.
Netty greatly simplifies and streamlines network programming such as TCP
and UDP socket server.
This camel component supports both producer and consumer endpoints.
The netty component has several options and allows fine-grained control
of a number of TCP/UDP communication parameters (buffer sizes, keepAlives,
tcpNoDelay etc) and facilitates both In-Only and In-Out communication on a
Camel route.
Maven users will need to add the following dependency to their pom.xml
for this component:
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org.apache.camelcamel-nettyx.x.x
URI format
The URI scheme for a netty component is as follows
netty:tcp://localhost:99999[?options]
netty:udp://remotehost:99999/[?options]
This component supports producer and consumer endpoints for both TCP and
UDP.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Value
Description
keepAlive
true
Setting to ensure socket is not closed due to inactivity
tcpNoDelay
true
Setting to improve TCP protocol performance
broadcast
false
Setting to choose Multicast over UDP
connectTimeout
10000
Time to wait for a socket connection to be available. Value is in millis.
reuseAddress
true
Setting to facilitate socket multiplexing
sync
true
Setting to set endpoint as one-way or request-response
ssl
false
Setting to specify whether SSL encryption is applied to this endpoint
sendBufferSize
65536 bytes
The TCP/UDP buffer sizes to be used during outbound communication. Size is bytes.
receiveBufferSize
65536 bytes
The TCP/UDP buffer sizes to be used during inbound communication. Size is bytes.
corePoolSize
10
The number of allocated threads at component startup. Defaults to 10
maxPoolSize
100
The maximum number of threads that may be allocated to this endpoint. Defaults to 100
disconnect
false
Whether or not to disconnect(close) from Netty Channel right after use. Can be used for both
consumer and producer.
lazyChannelCreation
true
Channels can be lazily created to avoid exceptions, if the remote server is not up and running
when the Camel producer is started.
transferExchange
false
Only used for TCP. You can transfer the exchange over the wire instead of just the body. The
following fields are transferred: In body, Out body, fault body, In headers, Out headers, fault
headers, exchange properties, exchange exception. This requires that the objects are serializable.
Camel will exclude any non-serializable objects and log it at WARN level.
disconnectOnNoReply
true
If sync is enabled then this option dictates NettyConsumer if it should disconnect where there is
no reply to send back.
noReplyLogLevel
WARN
If sync is enabled this option dictates NettyConsumer which logging level to use when logging a
there is no reply to send back. Values are: FATAL, ERROR, INFO, DEBUG, OFF.
allowDefaultCodec
true
Camel 2.4: The netty component installs a default codec if both, encoder/deocder is null and
textline is false. Setting allowDefaultCodec to false prevents the netty component from installing
a default codec as the first element in the filter chain.
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textline
false
Camel 2.4: Only used for TCP. If no codec is specified, you can use this flag to indicate a text line
based codec; if not specified or the value is false, then Object Serialization is assumed over TCP.
delimiter
LINE
Camel 2.4: The delimiter to use for the textline codec. Possible values are LINE and NULL.
decoderMaxLineLength
1024
Camel 2.4: The max line length to use for the textline codec.
autoAppendDelimiter
true
Camel 2.4: Whether or not to auto append missing end delimiter when sending using the
textline codec.
encoding
null
Camel 2.4: The encoding (a charset name) to use for the textline codec. If not provided, Camel
will use the JVM default Charset.
workerCount
null
Camel 2.9: When netty works on nio mode, it uses default workerCount parameter from Netty,
which is cpu_core_threads*2. User can use this operation to override the default workerCount
from Netty
sslContextParametersRef
null
Camel 2.9: Reference to a org.apache.camel.util.jsse.SSLContextParameters in the
Registry. This reference overrides any configured SSLContextParameters at the component
level. See Using the JSSE Configuration Utility.
Registry based Options
Codec Handlers and SSL Keystores can be enlisted in the Registry, such as in
the Spring XML file.
The values that could be passed in, are the following:
Name
Description
passphrase
password setting to use in order to encrypt/decrypt payloads sent using SSH
keyStoreFormat
keystore format to be used for payload encryption. Defaults to "JKS" if not set
securityProvider
Security provider to be used for payload encryption. Defaults to "SunX509" if not set.
keyStoreFile
Client side certificate keystore to be used for encryption
trustStoreFile
Server side certificate keystore to be used for encryption
sslHandler
Reference to a class that could be used to return an SSL Handler
encoder
A custom Handler class that can be used to perform special marshalling of outbound payloads. Must override
org.jboss.netty.channel.ChannelDownStreamHandler.
encorders
A list of encoder to be used. You can use a String which have values separated by comma, and have the values be looked
up in the Registry. Just remember to prefix the value with # so Camel knows it should lookup.
decoder
A custom Handler class that can be used to perform special marshalling of inbound payloads. Must override
org.jboss.netty.channel.ChannelUpStreamHandler.
decoders
A list of decorder to be used. You can use a String which have values separated by comma, and have the values be looked
up in the Registry. Just remember to prefix the value with # so Camel knows it should lookup.
Sending Messages to/from a Netty endpoint
Netty Producer
In Producer mode, the component provides the ability to send payloads to a
socket endpoint
using either TCP or UDP protocols (with optional SSL support).
The producer mode supports both one-way and request-response based
operations.
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Netty Consumer
In Consumer mode, the component provides the ability to:
▪ listen on a specified socket using either TCP or UDP protocols (with
optional SSL support),
▪ receive requests on the socket using text/xml, binary and serialized
object based payloads and
▪ send them along on a route as message exchanges.
The consumer mode supports both one-way and request-response based
operations.
Usage Samples
A UDP Netty endpoint using Request-Reply and
serialized object payload
RouteBuilder builder = new RouteBuilder() {
public void configure() {
from("netty:udp://localhost:5155?sync=true")
.process(new Processor() {
public void process(Exchange exchange) throws Exception {
Poetry poetry = (Poetry) exchange.getIn().getBody();
poetry.setPoet("Dr. Sarojini Naidu");
exchange.getOut().setBody(poetry);
}
}
}
};
A TCP based Netty consumer endpoint using One-way
communication
RouteBuilder builder = new RouteBuilder() {
public void configure() {
from("netty:tcp://localhost:5150")
.to("mock:result");
}
};
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An SSL/TCP based Netty consumer endpoint using
Request-Reply communication
Using the JSSE Configuration Utility
As of Camel 2.9, the Netty component supports SSL/TLS configuration
through the Camel JSSE Configuration Utility. This utility greatly decreases
the amount of component specific code you need to write and is configurable
at the endpoint and component levels. The following examples demonstrate
how to use the utility with the Netty component.
Programmatic configuration of the component
KeyStoreParameters ksp = new KeyStoreParameters();
ksp.setResource("/users/home/server/keystore.jks");
ksp.setPassword("keystorePassword");
KeyManagersParameters kmp = new KeyManagersParameters();
kmp.setKeyStore(ksp);
kmp.setKeyPassword("keyPassword");
SSLContextParameters scp = new SSLContextParameters();
scp.setKeyManagers(kmp);
NettyComponent nettyComponent = getContext().getComponent("netty",
NettyComponent.class);
nettyComponent.setSslContextParameters(scp);
Spring DSL based configuration of endpoint
...
...
...
...
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Using Basic SSL/TLS configuration on the Jetty Component
JndiRegistry registry = new JndiRegistry(createJndiContext());
registry.bind("password", "changeit");
registry.bind("ksf", new File("src/test/resources/keystore.jks"));
registry.bind("tsf", new File("src/test/resources/keystore.jks"));
context.createRegistry(registry);
context.addRoutes(new RouteBuilder() {
public void configure() {
String netty_ssl_endpoint =
"netty:tcp://localhost:5150?sync=true&ssl=true&passphrase=#password"
+ "&keyStoreFile=#ksf&trustStoreFile=#tsf";
String return_string =
"When You Go Home, Tell Them Of Us And Say,"
+ "For Your Tomorrow, We Gave Our Today.";
from(netty_ssl_endpoint)
.process(new Processor() {
public void process(Exchange exchange) throws Exception {
exchange.getOut().setBody(return_string);
}
}
}
});
Using Multiple Codecs
In certain cases it may be necessary to add chains of encoders and decoders
to the netty pipeline. To add multpile codecs to a camel netty endpoint the
'encoders' and 'decoders' uri parameters should be used. Like the 'encoder'
and 'decoder' parameters they are used to supply references (to lists of
ChannelUpstreamHandlers and ChannelDownstreamHandlers) that should be
added to the pipeline. Note that if encoders is specified then the encoder
param will be ignored, similarly for decoders and the decoder param.
The lists of codecs need to be added to the Camel's registry so they can
be resolved when the endpoint is created.
LengthFieldBasedFrameDecoder lengthDecoder = new
LengthFieldBasedFrameDecoder(1048576, 0, 4, 0, 4);
StringDecoder stringDecoder = new StringDecoder();
registry.bind("length-decoder", lengthDecoder);
registry.bind("string-decoder", stringDecoder);
LengthFieldPrepender lengthEncoder = new LengthFieldPrepender(4);
StringEncoder stringEncoder = new StringEncoder();
registry.bind("length-encoder", lengthEncoder);
registry.bind("string-encoder", stringEncoder);
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List decoders = new ArrayList();
decoders.add(lengthDecoder);
decoders.add(stringDecoder);
List encoders = new ArrayList();
encoders.add(lengthEncoder);
encoders.add(stringEncoder);
registry.bind("encoders", encoders);
registry.bind("decoders", decoders);
Spring's native collections support can be used to specify the codec lists in
an application context
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The bean names can then be used in netty endpoint definitions either as a
comma separated list or contained in a List e.g.
from("direct:multiple-codec").to("netty:tcp://localhost:{{port}}?encoders=#encoders&sync=false");
from("netty:tcp://localhost:{{port}}?decoders=#length-decoder,#string-decoder&sync=false").to("mock:mu
}
};
}
}
or via spring.
Closing Channel When Complete
When acting as a server you sometimes want to close the channel when, for
example, a client conversion is finished.
You can do this by simply setting the endpoint option disconnect=true.
However you can also instruct Camel on a per message basis as follows.
To instruct Camel to close the channel, you should add a header with the key
CamelNettyCloseChannelWhenComplete set to a boolean true value.
For instance, the example below will close the channel after it has written the
bye message back to the client:
from("netty:tcp://localhost:8080").process(new Processor() {
public void process(Exchange exchange) throws Exception {
String body = exchange.getIn().getBody(String.class);
exchange.getOut().setBody("Bye " + body);
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// some condition which determines if we should close
if (close) {
exchange.getOut().setHeader(NettyConstants.NETTY_CLOSE_CHANNEL_WHEN_COMPLETE, true);
}
}
});
Adding custom channel pipeline factories to gain complete control
over a created pipeline
Available as of Camel 2.5
Custom channel pipelines provide complete control to the user over the
handler/interceptor chain by inserting custom handler(s), encoder(s) &
decoders without having to specify them in the Netty Endpoint URL in a very
simple way.
In order to add a custom pipeline, a custom channel pipeline factory must
be created and registered with the context via the context registry
(JNDIRegistry,or the camel-spring ApplicationContextRegistry etc).
A custom pipeline factory must be constructed as follows
• A Producer linked channel pipeline factory must extend the abstract
class ClientPipelineFactory.
• A Consumer linked channel pipeline factory must extend the abstract
class ServerPipelineFactory.
• The classes can optionally override the getPipeline() method in order
to insert custom handler(s), encoder(s) and decoder(s). Not
overriding the getPipeline() method creates a pipeline with no
handlers, encoders or decoders wired to the pipeline.
The example below shows how ServerChannel Pipeline factory may be
created
public class SampleServerChannelPipelineFactory extends ServerPipelineFactory {
private int maxLineSize = 1024;
private boolean invoked;
public ChannelPipeline getPipeline() throws Exception {
invoked = true;
ChannelPipeline channelPipeline = Channels.pipeline();
channelPipeline.addLast("encoder-SD", new StringEncoder(CharsetUtil.UTF_8));
channelPipeline.addLast("decoder-DELIM", new
DelimiterBasedFrameDecoder(maxLineSize, true, Delimiters.lineDelimiter()));
channelPipeline.addLast("decoder-SD", new StringDecoder(CharsetUtil.UTF_8));
channelPipeline.addLast("handler", new ServerChannelHandler(consumer));
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return channelPipeline;
}
public boolean isfactoryInvoked() {
return invoked;
}
}
The custom channel pipeline factory can then be added to the registry and
instantiated/utilized on a camel route in the following way
Registry registry = camelContext.getRegistry();
serverPipelineFactory = new TestServerChannelPipelineFactory();
registry.bind("spf", serverPipelineFactory);
context.addRoutes(new RouteBuilder() {
public void configure() {
String netty_ssl_endpoint =
"netty:tcp://localhost:5150?serverPipelineFactory=#spf"
String return_string =
"When You Go Home, Tell Them Of Us And Say,"
+ "For Your Tomorrow, We Gave Our Today.";
from(netty_ssl_endpoint)
.process(new Processor() {
public void process(Exchange exchange) throws Exception {
exchange.getOut().setBody(return_string);
}
}
}
});
See Also
•
•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
MINA
NMR COMPONENT
The nmr component is an adapter to the Normalized Message Router (NMR)
in ServiceMix, which is intended for use by Camel applications deployed
directly into the OSGi container. You can exchange objects with NMR and not
only XML like this is the case with the JBI specification. The interest of this
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
834
component is that you can interconnect camel routes deployed in different
OSGI bundles.
By contrast, the JBI component is intended for use by Camel applications
deployed into the ServiceMix JBI container.
Installing
The NMR component is provided with Apache ServiceMix. It is not distributed
with Camel. To install the NMR component in ServiceMix, enter the following
command in the ServiceMix console window:
features install nmr
You also need to instantiate the NMR component. You can do this by editing
your Spring configuration file, META-INF/spring/*.xml, and adding the
following bean instance:
...
...
NMR consumer and producer endpoints
The following code:
from("nmr:MyServiceEndpoint")
Automatically exposes a new endpoint to the bus with endpoint name
MyServiceEndpoint (see URI-format).
When an NMR endpoint appears at the end of a route, for example:
to("nmr:MyServiceEndpoint")
The messages sent by this producer endpoint are sent to the already
deployed JBI endpoint.
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URI format
nmr:endpointName
URI Options
Option
Default
Value
Description
runAsSubject
false
Apache ServiceMix 4.4: When this is set to true on a consumer endpoint, the endpoint will be invoked on
behalf of the Subject that is set on the Exchange (i.e. the call to
Subject.getSubject(AccessControlContext) will return the Subject instance)
synchronous
false
When this is set to true on a consumer endpoint, an incoming, synchronous NMR Exchange will be handled on
the sender's thread instead of being handled on a new thread of the NMR endpoint's thread pool
timeout
0
Apache ServiceMix 4.4: When this is set to a value greater than 0, the producer endpoint will timeout if it
doesn't receive a response from the NMR within the given timeout period (in milliseconds). Configuring a
timeout value will switch to using synchronous interactions with the NMR instead of the usual asynchronous
messaging.
Examples
Consumer
from("nmr:MyServiceEndpoint") // consume nmr exchanges asynchronously
from("nmr:MyServiceEndpoint?synchronous=true").to() // consume nmr exchanges
synchronously and use the same thread as defined by NMR ThreadPool
Producer
from()...to("nmr:MyServiceEndpoint") // produce nmr exchanges asynchronously
from()...to("nmr:MyServiceEndpoint?timeout=10000") // produce nmr exchanges
synchronously and wait till 10s to receive response
Using Stream bodies
If you are using a stream type as the message body, you should be aware
that a stream is only capable of being read once. So if you enable DEBUG
logging, the body is usually logged and thus read. To deal with this, Camel
has a streamCaching option that can cache the stream, enabling you to read
it multiple times.
from("nmr:MyEndpoint").streamCaching().to("xslt:transform.xsl", "bean:doSomething");
From Camel 1.5 onwards, the stream caching is default enabled, so it is not
necessary to set the streamCaching() option.
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In Camel 2.0 we store big input streams (by default, over 64K) in a temp file
using CachedOutputStream. When you close the input stream, the temp file
will be deleted.
Testing
NMR camel routes can be tested using the camel unit test approach even if
they will be deployed next in different bundles on an OSGI runtime. With this
aim in view, you will extend the ServiceMixNMR Mock class
org.apache.servicemix.camel.nmr.AbstractComponentTest which will
create a NMR bus, register the Camel NMR Component and the endpoints
defined into the Camel routes.
public class ExchangeUsingNMRTest extends AbstractComponentTest {
@Test
public void testProcessing() throws InterruptedException {
MockEndpoint mock = getMockEndpoint("mock:simple");
mock.expectedBodiesReceived("Simple message body");
template.sendBody("direct:simple", "Simple message body");
assertMockEndpointsSatisfied();
}
@Override
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
from("direct:simple").to("nmr:simple");
from("nmr:simple?synchronous=true").to("mock:simple");
}
};
}
}
See Also
•
•
•
•
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Component
Endpoint
Getting Started
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
QUARTZ COMPONENT
The quartz: component provides a scheduled delivery of messages using
the Quartz scheduler.
Each endpoint represents a different timer (in Quartz terms, a Trigger and
JobDetail).
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-quartzx.x.x
URI format
quartz://timerName?options
quartz://groupName/timerName?options
quartz://groupName/timerName/cronExpression
quartz://groupName/timerName/?cron=expression
quartz://timerName?cron=expression
(@deprecated)
(Camel 2.0)
(Camel 2.0)
The component uses either a CronTrigger or a SimpleTrigger. If no cron
expression is provided, the component uses a simple trigger. If no groupName
is provided, the quartz component uses the Camel group name.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Parameter
Default
Description
cron
None
Specifies a cron expression (not compatible with the trigger.* or job.* options).
trigger.repeatCount
0
SimpleTrigger: How many times should the timer repeat?
trigger.repeatInterval
0
SimpleTrigger: The amount of time in milliseconds between repeated triggers.
job.name
null
Sets the job name.
job.XXX
null
Sets the job option with the XXX setter name.
trigger.XXX
null
Sets the trigger option with the XXX setter name.
stateful
false
Uses a Quartz StatefulJob instead of the default job.
fireNow
false
New to Camel 2.2.0, if it is true will fire the trigger when the route is start when using
SimpleTrigger.
For example, the following routing rule will fire two timer events to the
mock:results endpoint:
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Using cron expressions
Configuring the cron expression in Camel 1.x is based on path
separators. We changed this to an URI option in Camel 2.0, allowing
a more elegant configuration.
Also it is not possible to use the / cron special character (for
increments) in Camel 1.x, which Camel 2.0 also fixes.
You may need to escape certain URI characters such as using ? in the
quartz cron expression.
from("quartz://myGroup/
myTimerName?trigger.repeatInterval=2&trigger.repeatCount=1").routeId("myRoute").to("mock:result");
When using a StatefulJob, the JobDataMap is re-persisted after every
execution of the job, thus preserving state for the next execution.
Configuring quartz.properties file
By default Quartz will look for a quartz.properties file in the root of the
classpath. If you are using WAR deployments this means just drop the
quartz.properties in WEB-INF/classes.
However the Camel Quartz component also allows you to configure
properties:
Parameter
Default
Type
Description
properties
null
Properties
Camel 2.4: You can configure a java.util.Propoperties instance.
propertiesFile
null
String
Camel 2.4: File name of the properties to load from the classpath
To do this you can configure this in Spring XML as follows
Starting the Quartz scheduler
Available as of Camel 2.4
The Quartz component offers an option to let the Quartz scheduler be
started delayed, or not auto started at all.
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Parameter
Default
Type
Description
startDelayedSeconds
0
int
Camel 2.4: Seconds to wait before starting the quartz scheduler.
autoStartScheduler
true
boolean
Camel 2.4: Whether or not the scheduler should be auto started.
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To do this you can configure this in Spring XML as follows
Clustering
Available as of Camel 2.4
If you use Quartz in clustered mode, e.g. the JobStore is clustered. Then
from Camel 2.4 onwards the Quartz component will not pause/remove
triggers when a node is being stopped/shutdown. This allows the trigger to
keep running on the other nodes in the cluster.
Note: When running in clustered node no checking is done to ensure
unique job name/group for endpoints.
Message Headers
Camel adds the getters from the Quartz Execution Context as header values.
The following headers are added:
calendar, fireTime, jobDetail, jobInstance, jobRuntTime,
mergedJobDataMap, nextFireTime, previousFireTime, refireCount,
result, scheduledFireTime, scheduler, trigger, triggerName,
triggerGroup.
The fireTime header contains the java.util.Date of when the exchange
was fired.
Using Cron Triggers
Available as of Camel 2.0
Quartz supports Cron-like expressions for specifying timers in a handy
format. You can use these expressions in the cron URI parameter; though to
preserve valid URI encoding we allow + to be used instead of spaces. Quartz
provides a little tutorial on how to use cron expressions.
For example, the following will fire a message every five minutes starting
at 12pm (noon) to 6pm on weekdays:
from("quartz://myGroup/myTimerName?cron=0+0/
5+12-18+?+*+MON-FRI").to("activemq:Totally.Rocks");
which is equivalent to using the cron expression
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0 0/5 12-18 ? * MON-FRI
The following table shows the URI character encodings we use to preserve
valid URI syntax:
URI Character
Cron character
+
Space
Using Cron Triggers in Camel 1.x
@deprecated
Quartz supports Cron-like expressions for specifying timers in a handy
format. You can use these expressions in the URI; though to preserve valid
URI encoding we allow / to be used instead of spaces and $ to be used
instead of ?.
For example, the following endpoint URI will fire a message at 12pm
(noon) every day
from("quartz://myGroup/myTimerName/0/0/12/*/*/$").to("activemq:Totally.Rocks");
which is equivalent to using the cron expression
0 0 12 * * ?
The following table shows the URI character encodings we use to preserve
valid URI syntax:
URI Character
Cron character
/
Space
$
?
Specifying time zone
Available as of Camel 2.8.1
The Quartz Scheduler allows you to configure time zone per trigger. For
example to use a timezone of your country, then you can do as follows:
quartz://groupName/timerName?cron=0+0/5+12-18+?+*+MON-FRI&trigger.timeZone=Europe/
Stockholm
The timeZone value is the values accepted by java.util.TimeZone.
In Camel 2.8.0 or older versions you would have to provide your custom
String to java.util.TimeZone Type Converter to be able configure this
from the endpoint uri.
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From Camel 2.8.1 onwards we have included such a Type Converter in the
camel-core.
See Also
•
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
Timer
QUICKFIX/J COMPONENT
Available as of Camel 2.0
The quickfix component adapts the QuickFIX/J FIX engine for using in
Camel . This component uses the standard Financial Interchange (FIX)
protocol for message transport.
Maven users will need to add the following dependency to their pom.xml for
this component:
org.apache.camelcamel-quickfixx.x.x
URI format
quickfix:configFile[?sessionID=sessionID]
The configFile is the name of the QuickFIX/J configuration to use for the FIX
engine (located as a resource found in your classpath). The optional
sessionID identifies a specific FIX session. The format of the sessionID is:
(BeginString):(SenderCompID)[/(SenderSubID)[/(SenderLocationID)]]->(TargetCompID)[/
(TargetSubID)[/(TargetLocationID)]]
Example URIs:
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Previous Versions
The quickfix component was rewritten for Camel 2.5. For
information about using the quickfix component prior to 2.5 see
the documentation section below.
quickfix:config.cfg
quickfix:config.cfg?sessionID=FIX.4.2:MyTradingCompany->SomeExchange
ENDPOINTS
FIX sessions are endpoints for the quickfix component. An endpoint URI may
specify a single session or all sessions managed by a specific QuickFIX/J
engine. Typical applications will use only one FIX engine but advanced users
may create multiple FIX engines by referencing different configuration files in
quickfix component endpoint URIs.
When a consumer does not include a session ID in the endpoint URI, it will
receive exchanges for all sessions managed by the FIX engine associated
with the configuration file specified in the URI. If a producer does not specify
a session in the endpoint URI then it must include the session-related fields
in the FIX message being sent. If a session is specified in the URI then the
component will automatically inject the session-related fields into the FIX
message.
Exchange Format
The exchange headers include information to help with exchange filtering,
routing and other processing. The following headers are available:
Header
Name
Description
EventCategory
One of AppMessageReceived, AppMessageSent, AdminMessageReceived, AdminMessageSent, SessionCreated,
SessionLogon, SessionLogoff. See the QuickfixjEventCategory enum.
SessionID
The FIX message SessionID
MessageType
The FIX MsgType tag value
DataDictionary
Specifies a data dictionary to used for parsing an incoming message. Can be an instance of a data dictionary or a resource
path for a QuickFIX/J data dictionary file
The DataDictionary header is useful if string messages are being received
and need to be parsed in a route. QuickFIX/J requires a data dictionary to
parse certain types of messages (with repeating groups, for example). By
injecting a DataDictionary header in the route after receiving a message
string, the FIX engine can properly parse the data.
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QuickFIX/J Configuration Extensions
When using QuickFIX/J directly, one typically writes code to create instances
of logging adapters, message stores and communication connectors. The
quickfix component will automatically create instances of these classes
based on information in the configuration file. It also provides defaults for
many of the common required settings and adds additional capabilities (like
the ability to activate JMX support).
The following sections describe how the quickfix component processes
the QuickFIX/J configuration. For comprehensive information about QuickFIX/J
configuration, see the QFJ user manual.
Communication Connectors
When the component detects an initiator or acceptor session setting in the
QuickFIX/J configuration file it will automatically create the corresponding
initiator and/or acceptor connector. These settings can be in the default or in
a specific session section of the configuration file.
Session Setting
Component Action
ConnectionType=initiator
Create an initiator connector
ConnectionType=acceptor
Create an acceptor connector
The threading model for the QuickFIX/J session connectors can also be
specified. These settings affect all sessions in the configuration file and must
be placed in the settings default section.
Default/Global Setting
Component Action
ThreadModel=ThreadPerConnector
Use SocketInitiator or SocketAcceptor (default)
ThreadModel=ThreadPerSession
Use ThreadedSocketInitiator or ThreadedSocketAcceptor
Logging
The QuickFIX/J logger implementation can be specified by including the
following settings in the default section of the configuration file. The
ScreenLog is the default if none of the following settings are present in the
configuration. It's an error to include settings that imply more than one log
implementation. The log factory implementation can also be set directly on
the Quickfix component. This will override any related values in the
QuickFIX/J settings file.
Default/Global Setting
Component Action
ScreenLogShowEvents
Use a ScreenLog
ScreenLogShowIncoming
Use a ScreenLog
ScreenLogShowOutgoing
Use a ScreenLog
SLF4J*
Camel 2.6+. Use a SLF4JLog. Any of the SLF4J settings will cause this log to be used.
FileLogPath
Use a FileLog
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JdbcDriver
Use a JdbcLog
Message Store
The QuickFIX/J message store implementation can be specified by including
the following settings in the default section of the configuration file. The
MemoryStore is the default if none of the following settings are present in the
configuration. It's an error to include settings that imply more than one
message store implementation. The message store factory implementation
can also be set directly on the Quickfix component. This will override any
related values in the QuickFIX/J settings file.
Default/Global Setting
Component Action
JdbcDriver
Use a JdbcStore
FileStorePath
Use a FileStore
SleepycatDatabaseDir
Use a SleepcatStore
Message Factory
A message factory is used to construct domain objects from raw FIX
messages. The default message factory is DefaultMessageFactory.
However, advanced applications may require a custom message factory. This
can be set on the QuickFIX/J component.
JMX
Default/Global Setting
Component Action
UseJmx
if Y, then enable QuickFIX/J JMX
Other Defaults
The component provides some default settings for what are normally
required settings in QuickFIX/J configuration files. SessionStartTime and
SessionEndTime default to "00:00:00", meaning the session will not be
automatically started and stopped. The HeartBtInt (heartbeat interval)
defaults to 30 seconds.
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Minimal Initiator Configuration Example
[SESSION]
ConnectionType=initiator
BeginString=FIX.4.4
SenderCompID=YOUR_SENDER
TargetCompID=YOUR_TARGET
Using the InOut Message Exchange Pattern
Camel 2.8+
Although the FIX protocol is event-driven and asynchronous, there are
specific pairs of messages
that represent a request-reply message exchange. To use an InOut exchange
pattern, there should
be a single request message and single reply message to the request.
Examples include an
OrderStatusRequest message and UserRequest.
Implementing InOut Exchanges for Consumers
Add "exchangePattern=InOut" to the QuickFIX/J enpoint URI. The
MessageOrderStatusService in
the example below is a bean with a synchronous service method. The
method returns the response
to the request (an ExecutionReport in this case) which is then sent back to
the requestor session.
from("quickfix:examples/
inprocess.cfg?sessionID=FIX.4.2:MARKET->TRADER&exchangePattern=InOut")
.filter(header(QuickfixjEndpoint.MESSAGE_TYPE_KEY).isEqualTo(MsgType.ORDER_STATUS_REQUEST))
.bean(new MarketOrderStatusService());
Implementing InOut Exchanges for Producers
For producers, sending a message will block until a reply is received or a
timeout occurs. There
is no standard way to correlate reply messages in FIX. Therefore, a
correlation criteria must be
defined for each type of InOut exchange. The correlation criteria and timeout
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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can be specified
using Exchange properties.
Description
Key String
Key Constant
D
Correlation
Criteria
"CorrelationCriteria"
QuickfixjProducer.CORRELATION_CRITERIA_KEY
N
Correlation
Timeout in
Milliseconds
"CorrelationTimeout"
QuickfixjProducer.CORRELATION_TIMEOUT_KEY
1
The correlation criteria is defined with a MessagePredicate object. The
following example will treat
a FIX ExecutionReport from the specified session where the transaction type
is STATUS and the Order ID
matches our request. The session ID should be for the requestor, the sender
and target CompID fields
will be reversed when looking for the reply.
exchange.setProperty(QuickfixjProducer.CORRELATION_CRITERIA_KEY,
new MessagePredicate(new SessionID(sessionID), MsgType.EXECUTION_REPORT)
.withField(ExecTransType.FIELD, Integer.toString(ExecTransType.STATUS))
.withField(OrderID.FIELD, request.getString(OrderID.FIELD)));
Example
The source code contains an example called RequestReplyExample that
demonstrates the InOut exchanges
for a consumer and producer. This example creates a simple HTTP server
endpoint that accepts order
status requests. The HTTP request is converted to a FIX
OrderStatusRequestMessage, is augmented with a
correlation criteria, and is then routed to a quickfix endpoint. The response is
then converted to a
JSON-formatted string and sent back to the HTTP server endpoint to be
provided as the web response.
Spring Configuration
Camel 2.6+
The QuickFIX/J component includes a Spring FactoryBean for configuring
the session settings within a Spring context. A type converter for QuickFIX/J
session ID strings is also included. The following example shows a simple
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configuration of an acceptor and initiator session with default settings for
both sessions.
${in.header.EventCategory} == 'AppMessageReceived'
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Exception handling
QuickFIX/J behavior can be modified if certain exceptions are thrown during
processing of a message. If a RejectLogon exception is thrown while
processing an incoming logon administrative message, then the logon will be
rejected.
Normally, QuickFIX/J handles the logon process automatically. However,
sometimes an outgoing logon message must be modified to include
credentials required by a FIX counterparty. If the FIX logon message body is
modified when sending a logon message
(EventCategory=AdminMessageSent the modified message will be sent to the
counterparty. It is important that the outgoing logon message is being
processed synchronously. If it is processed asynchronously (on another
thread), the FIX engine will immediately send the unmodified outgoing
message when it's callback method returns.
FIX Sequence Number Management
If an application exception is thrown during synchronous exchange
processing, this will cause QuickFIX/J to not increment incoming FIX message
sequence numbers and will cause a resend of the counterparty message.
This FIX protocol behavior is primarily intended to handle transport errors
rather than application errors. There are risks associated with using this
mechanism to handle application errors. The primary risk is that the message
will repeatedly cause application errors each time it's re-received. A better
solution is to persist the incoming message (database, JMS queue)
immediately before processing it. This also allows the application to process
messages asynchronously without losing messages when errors occur.
Although it's possible to send messages to a FIX session before it's logged
on (the messages will be sent at logon time), it is usually a better practice to
wait until the session is logged on. This eliminates the required sequence
number resynchronization steps at logon. Waiting for session logon can be
done by setting up a route that processes the SessionLogon event category
and signals the application to start sending messages.
See the FIX protocol specifications and the QuickFIX/J documentation for
more details about FIX sequence number management.
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Route Examples
Several examples are included in the QuickFIX/J component source code (test
subdirectories). One of these examples implements a trival trade excecution
simulation. The example defines an application component that uses the URI
scheme "trade-executor".
The following route receives messages for the trade executor session and
passes application messages to the trade executor component.
from("quickfix:examples/inprocess.cfg?sessionID=FIX.4.2:MARKET->TRADER").
filter(header(QuickfixjEndpoint.EVENT_CATEGORY_KEY).isEqualTo(QuickfixjEventCategory.AppMessageReceive
to("trade-executor:market");
The trade executor component generates messages that are routed back to
the trade session. The session ID must be set in the FIX message itself since
no session ID is specified in the endpoint URI.
from("trade-executor:market").to("quickfix:examples/inprocess.cfg");
The trader session consumes execution report messages from the market
and processes them.
from("quickfix:examples/inprocess.cfg?sessionID=FIX.4.2:TRADER->MARKET").
filter(header(QuickfixjEndpoint.MESSAGE_TYPE_KEY).isEqualTo(MsgType.EXECUTION_REPORT)).
bean(new MyTradeExecutionProcessor());
QUICKFIX/J COMPONENT PRIOR TO CAMEL 2.5
Available since Camel 2.0
The quickfix component is an implementation of the QuickFIX/J engine for
Java . This engine allows to connect to a FIX server which is used to
exchange financial messages according to FIX protocol standard.
Note: The component can be used to send/receives messages to a FIX
server.
URI format
quickfix-server:config file
quickfix-client:config file
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Where config file is the location (in your classpath) of the quickfix
configuration file used to configure the engine at the startup.
Note: Information about parameters available for quickfix can be found on
QuickFIX/J web site.
The quickfix-server endpoint must be used to receive from FIX server FIX
messages and quickfix-client endpoint in the case that you want to send
messages to a FIX gateway.
Exchange data format
The QuickFIX/J engine is like CXF component a messaging bus using MINA as
protocol layer to create the socket connection with the FIX engine gateway.
When QuickFIX/J engine receives a message, then it create a
QuickFix.Message instance which is next received by the camel endpoint.
This object is a 'mapping object' created from a FIX message formatted
initially as a collection of key value pairs data. You can use this object or you
can use the method 'toString' to retrieve the original FIX message.
Note: Alternatively, you can use camel bindy dataformat to transform the
FIX message into your own java POJO
When a message must be send to QuickFix, then you must create a
QuickFix.Message instance.
Samples
Direction : to FIX gateway
// bean method in charge to
transform message into a QuickFix.Message
// Quickfix engine who
will send the FIX messages to the gateway
Direction : from FIX gateway
// QuickFix engine who
will receive the message from FIX gateway
// bean method parsing the
QuickFix.Message
"
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See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
PRINTER COMPONENT
Available as of Camel 2.1
The printer component provides a way to direct payloads on a route to a
printer. Obviously the payload has to be a formatted piece of payload in
order for the component to appropriately print it. The objective is to be able
to direct specific payloads as jobs to a line printer in a camel flow.
This component only supports a camel producer endpoint.
The functionality allows for the payload to be printed on a default printer,
named local, remote or wirelessly linked printer using the javax printing API
under the covers.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-printerx.x.x
URI format
Since the URI scheme for a printer has not been standardized (the nearest
thing to a standard being the IETF print standard) and therefore not uniformly
applied by vendors, we have chosen "lpr" as the scheme.
lpr://localhost/default[?options]
lpr://remotehost:port/path/to/printer[?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default Value
Description
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mediaSize
MediaSizeName.NA_LETTER
Sets the stationary as defined by enumeration settings in the
javax.print.attribute.standard.MediaSizeName API. The default setting is to use North American
Letter sized stationary
copies
1
Sets number of copies based on the javax.print.attribute.standard.Copies API
sides
Sides.ONE_SIDED
Sets one sided or two sided printing based on the javax.print.attribute.standard.Sides API
flavor
DocFlavor.BYTE_ARRAY
Sets DocFlavor based on the javax.print.DocFlavor API
mimeType
AUTOSENSE
Sets mimeTypes supported by the javax.print.DocFlavor API
Sending Messages to a Printer
Printer Producer
Sending data to the printer is very straightforward and involves creating a
producer endpoint that can be sent message exchanges on in route.
Usage Samples
Example 1: Printing text based payloads on a Default
printer using letter stationary and one-sided mode
RouteBuilder builder = new RouteBuilder() {
public void configure() {
from(file://inputdir/?delete=true)
.to("lpr://localhost/default?copies=2" +
"&flavor=DocFlavor.INPUT_STREAM&" +
"&mimeType=AUTOSENSE" +
"&mediaSize=na-letter" +
"&sides=one-sided")
}};
Example 2: Printing GIF based payloads on a Remote
printer using A4 stationary and one-sided mode
RouteBuilder builder = new RouteBuilder() {
public void configure() {
from(file://inputdir/?delete=true)
.to("lpr://remotehost/sales/salesprinter" +
"?copies=2&sides=one-sided" +
"&mimeType=GIF&mediaSize=iso-a4" +
"&flavor=DocFlavor.INPUT_STREAM")
}};
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Example 3: Printing JPEG based payloads on a Remote
printer using Japanese Postcard stationary and onesided mode
RouteBuilder builder = new RouteBuilder() {
public void configure() {
from(file://inputdir/?delete=true)
.to("lpr://remotehost/sales/salesprinter" +
"?copies=2&sides=one-sided" +
"&mimeType=JPEG" +
"&mediaSize=japanese-postcard" +
"&flavor=DocFlavor.INPUT_STREAM")
}};
PROPERTIES COMPONENT
Available as of Camel 2.3
URI format
properties:key[?options]
Where key is the key for the property to lookup
Options
Name
Type
Default
Description
cache
boolean
true
Whether or not to cache loaded properties.
locations
String
null
A list of locations to load properties. You can use comma to separate multiple
locations. This option will override any default locations and only use the
locations from this option.
propertyPrefix
String
null
2.9 Optional prefix prepended to property names before resolution.
propertySuffix
String
null
2.9 Optional suffix appended to property names before resolution.
fallbackToUnaugmentedProperty
boolean
true
2.9 If true, first attempt resolution of property name augmented with
propertyPrefix and propertySuffix before falling back the plain property
name specified. If false, only the augmented property name is searched.
prefixToken
String
{{
2.9 The token to indicate the beginning of a property token.
suffixToken
String
}}
2.9 The token to indicate the end of a property token.
USING PROPERTYPLACEHOLDER
Available as of Camel 2.3
Camel now provides a new PropertiesComponent in camel-core which
allows you to use property placeholders when defining Camel Endpoint URIs.
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Resolving property from Java code
You can use the method resolvePropertyPlaceholders on the
CamelContext to resolve a property from any Java code.
This works much like you would do if using Spring's tag. However Spring have a limitation which prevents 3rd
party frameworks to leverage Spring property placeholders to the fullest. See
more at How do I use Spring Property Placeholder with Camel XML.
The property placeholder is generally in use when doing:
▪ lookup or creating endpoints
▪ lookup of beans in the Registry
▪ additional supported in Spring XML (see below in examples)
▪ using Blueprint PropertyPlaceholder with Camel Properties
component
Syntax
The syntax to use Camel's property placeholder is to use {{key}} for
example {{file.uri}} where file.uri is the property key.
You can use property placeholders in parts of the endpoint URI's which for
example you can use placeholders for parameters in the URIs.
PropertyResolver
As usually Camel provides a pluggable mechanism which allows 3rd part to
provide their own resolver to lookup properties. Camel provides a default
implementation
org.apache.camel.component.properties.DefaultPropertiesResolver
which is capable of loading properties from the file system, classpath or
Registry. You can prefix the locations with either:
▪ ref: Camel 2.4: to lookup in the Registry
▪ file: to load the from file system
▪ classpath: to load from classpath (this is also the default if no prefix
is provided)
▪ blueprint: Camel 2.7: to use a specific OSGi blueprint placeholder
service
Defining location
The PropertiesResolver need to know a location(s) where to resolve the
properties. You can define 1 to many locations. If you define the location in a
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single String property you can separate multiple locations with comma such
as:
pc.setLocation("com/mycompany/myprop.properties,com/mycompany/other.properties");
Using system and environment variables in locations
Available as of Camel 2.7
The location now supports using placeholders for JVM system properties
and OS environments variables.
For example:
location=file:${karaf.home}/etc/foo.properties
In the location above we defined a location using the file scheme using the
JVM system property with key karaf.home.
To use an OS environment variable instead you would have to prefix with
env:
location=file:${env:APP_HOME}/etc/foo.properties
Where APP_HOME is an OS environment.
You can have multiple placeholders in the same location, such as:
location=file:${env:APP_HOME}/etc/${prop.name}.properties
Configuring in Java DSL
You have to create and register the PropertiesComponent under the name
properties such as:
PropertiesComponent pc = new PropertiesComponent();
pc.setLocation("classpath:com/mycompany/myprop.properties");
context.addComponent("properties", pc);
Configuring in Spring XML
Spring XML offers two variations to configure. You can define a spring bean
as a PropertiesComponent which resembles the way done in Java DSL. Or
you can use the tag.
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Using the tag makes the configuration a bit more
fresh such as:
Using a Properties from the Registry
Available as of Camel 2.4
For example in OSGi you may want to expose a service which returns the
properties as a java.util.Properties object.
Then you could setup the Properties component as follows:
Where myProperties is the id to use for lookup in the OSGi registry. Notice
we use the ref: prefix to tell Camel that it should lookup the properties for
the Registry.
Examples using properties component
When using property placeholders in the endpoint URIs you can either use
the properties: component or define the placeholders directly in the URI.
We will show example of both cases, starting with the former.
// properties
cool.end=mock:result
// route
from("direct:start").to("properties:{{cool.end}}");
You can also use placeholders as a part of the endpoint uri:
// properties
cool.foo=result
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// route
from("direct:start").to("properties:mock:{{cool.foo}}");
In the example above the to endpoint will be resolved to mock:result.
You can also have properties with refer to each other such as:
// properties
cool.foo=result
cool.concat=mock:{{cool.foo}}
// route
from("direct:start").to("properties:mock:{{cool.concat}}");
Notice how cool.concat refer to another property.
The properties: component also offers you to override and provide a
location in the given uri using the locations option:
from("direct:start").to("properties:bar.end?locations=com/mycompany/
bar.properties");
Examples
You can also use property placeholders directly in the endpoint uris without
having to use properties:.
// properties
cool.foo=result
// route
from("direct:start").to("mock:{{cool.foo}}");
And you can use them in multiple wherever you want them:
// properties
cool.start=direct:start
cool.showid=true
cool.result=result
// route
from("{{cool.start}}")
.to("log:{{cool.start}}?showBodyType=false&showExchangeId={{cool.showid}}")
.to("mock:{{cool.result}}");
You can also your property placeholders when using ProducerTemplate for
example:
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template.sendBody("{{cool.start}}", "Hello World");
Example with Simple language
The Simple language now also support using property placeholders, for
example in the route below:
// properties
cheese.quote=Camel rocks
// route
from("direct:start")
.transform().simple("Hi ${body} do you think ${properties:cheese.quote}?");
You can also specify the location in the Simple language for example:
// bar.properties
bar.quote=Beer tastes good
// route
from("direct:start")
.transform().simple("Hi ${body}. ${properties:com/mycompany/
bar.properties:bar.quote}.");
Additional property placeholder supported in Spring XML
The property placeholders is also supported in many of the Camel Spring
XML tags such as , , ,
, , , and the others.
The example below has property placeholder in the tag:
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You can also define property placeholders in the various attributes on the
tag such as trace as shown here:
${in.body} World!
Overriding a property setting using a JVM System Property
Available as of Camel 2.5
It is possible to override a property value at runtime using a JVM System
property without the need to restart the application to pick up the change.
This may also be accomplished from the command line by creating a JVM
System property of the same name as the property it replaces with a new
value. An example of this is given below
PropertiesComponent pc = context.getComponent("properties",
PropertiesComponent.class);
pc.setCache(false);
System.setProperty("cool.end", "mock:override");
System.setProperty("cool.result", "override");
context.addRoutes(new RouteBuilder() {
@Override
public void configure() throws Exception {
from("direct:start").to("properties:cool.end");
from("direct:foo").to("properties:mock:{{cool.result}}");
}
});
context.start();
getMockEndpoint("mock:override").expectedMessageCount(2);
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template.sendBody("direct:start", "Hello World");
template.sendBody("direct:foo", "Hello Foo");
System.clearProperty("cool.end");
System.clearProperty("cool.result");
assertMockEndpointsSatisfied();
Using property placeholders for any kind of attribute in the XML DSL
Available as of Camel 2.7
Previously it was only the xs:string type attributes in the XML DSL that
support placeholders. For example often a timeout attribute would be a
xs:int type and thus you cannot set a string value as the placeholder key.
This is now possible from Camel 2.7 onwards using a special placeholder
namespace.
In the example below we use the prop prefix for the namespace
http://camel.apache.org/schema/placeholder by which we can use the
prop prefix in the attributes in the XML DSLs. Notice how we use that in the
Multicast to indicate that the option stopOnException should be the value of
the placeholder with the key "stop".
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In our properties file we have the value defined as
stop=true
Using property placeholder in the Java DSL
Available as of Camel 2.7
Likewise we have added support for defining placeholders in the Java DSL
using the new placeholder DSL as shown in the following equivalent
example:
from("direct:start")
// use a property placeholder for the option stopOnException on the Multicast EIP
// which should have the value of {{stop}} key being looked up in the properties
file
.multicast().placeholder("stopOnException", "stop")
.to("mock:a").throwException(new IllegalAccessException("Damn")).to("mock:b");
Using Blueprint property placeholder with Camel routes
Available as of Camel 2.7
Camel supports Blueprint which also offers a property placeholder service.
Camel supports convention over configuration, so all you have to do is to
define the OSGi Blueprint property placeholder in the XML file as shown
below:
Listing 85. Using OSGi blueprint property placeholders in Camel routes
By default Camel detects and uses OSGi blueprint property placeholder
service. You can disable this by setting the attribute
useBlueprintPropertyResolver to false on the definition.
You can also explicit refer to a specific OSGi blueprint property placeholder
by its id. For that you need to use the Camel's as
shown in the example below:
Listing 86. Explicit referring to a OSGi blueprint placeholder in Camel
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About placeholder syntaxes
Notice how we can use the Camel syntax for placeholders {{ }} in
the Camel route, which will lookup the value from OSGi blueprint.
The blueprint syntax for placeholders is ${ }. So outside the
you must use the ${ } syntax. Where as inside
you must use {{ }} syntax.
OSGi blueprint allows you to configure the syntax, so you can
actually align those if you want.
Notice how we use the blueprint scheme to refer to the OSGi blueprint
placeholder by its id. This allows you to mix and match, for example you can
also have additional schemes in the location. For example to load a file from
the classpath you can do:
location="blueprint:myblueprint.placeholder,classpath:myproperties.properties"
Each location is separated by comma.
See Also
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•
•
•
Configuring Camel
Component
Endpoint
Getting Started
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▪ Jasypt for using encrypted values (eg passwords) in the properties
REF COMPONENT
The ref: component is used for lookup of existing endpoints bound in the
Registry.
URI format
ref:someName
Where someName is the name of an endpoint in the Registry (usually, but
not always, the Spring registry). If you are using the Spring registry,
someName would be the bean ID of an endpoint in the Spring registry.
Runtime lookup
This component can be used when you need dynamic discovery of endpoints
in the Registry where you can compute the URI at runtime. Then you can look
up the endpoint using the following code:
// lookup the endpoint
String myEndpointRef = "bigspenderOrder";
Endpoint endpoint = context.getEndpoint("ref:" + myEndpointRef);
Producer producer = endpoint.createProducer();
Exchange exchange = producer.createExchange();
exchange.getIn().setBody(payloadToSend);
// send the exchange
producer.process(exchange);
...
And you could have a list of endpoints defined in the Registry such as:
...
Sample
In the sample below we use the ref: in the URI to reference the endpoint
with the spring ID, endpoint2:
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You could, of course, have used the ref attribute instead:
Which is the more common way to write it.
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
RESTLET COMPONENT
The Restlet component provides Restlet based endpoints for consuming and
producing RESTful resources.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-restletx.x.x
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URI format
restlet:restletUrl[?options]
Format of restletUrl:
protocol://hostname[:port][/resourcePattern]
Restlet promotes decoupling of protocol and application concerns. The
reference implementation of Restlet Engine supports a number of protocols.
However, we have tested the HTTP protocol only. The default port is port 80.
We do not automatically switch default port based on the protocol yet.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default Value
Description
headerFilterStrategy=#refName
(2.x or later)
An instance of
RestletHeaderFilterStrategy
Use the # notation (headerFilterStrategy=#refName) to reference a
header filter strategy in the Camel Registry. The strategy will be
plugged into the restlet binding if it is HeaderFilterStrategyAware.
restletBindingRef (1.x),
restletBinding=#refName (2.x
or later)
An instance of
DefaultRestletBinding
The bean ID of a RestletBinding object in the Camel Registry.
restletMethod
GET
On a producer endpoint, specifies the request method to use. On a
consumer endpoint, specifies that the endpoint consumes only
restletMethod requests. The string value is converted to
org.restlet.data.Method by the Method.valueOf(String) method.
restletMethods (2.x or later)
None
Consumer only Specify one or more methods separated by commas
(e.g. restletMethods=post,put) to be serviced by a restlet consumer
endpoint. If both restletMethod and restletMethods options are
specified, the restletMethod setting is ignored.
restletRealmRef (1.x),
restletRealm=#refName (2.x or
later)
null
The bean ID of the Realm Map in the Camel Registry.
restletUriPatterns=#refName
(2.x or later)
None
Consumer only Specify one ore more URI templates to be serviced by
a restlet consumer endpoint, using the # notation to reference a
List in the Camel Registry. If a URI pattern has been defined
in the endpoint URI, both the URI pattern defined in the endpoint and
the restletUriPatterns option will be honored.
throwExceptionOnFailure (2.6
or later)
true
*Producer only * Throws exception on a producer failure.
Message Headers
Camel 1.x
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Name
Type
Description
org.apache.camel.restlet.auth.login
String
Login name for basic authentication. It is set on the IN message by the application
and gets filtered before the restlet request header by Camel.
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org.apache.camel.restlet.auth.password
String
Password name for basic authentication. It is set on the IN message by the
application and gets filtered before the restlet request header by Camel.
org.apache.camel.restlet.mediaType
String
Specifies the content type, which can be set on the OUT message by the application/
processor. The value is the content-type of the response message. If this header is
not set, the content-type is set based on the object type of the OUT message body.
org.apache.camel.restlet.queryString
String
The query string of the request URI. It is set on the IN message by
DefaultRestletBinding when the restlet component receives a request.
org.apache.camel.restlet.responseCode
String
or
Integer
The response code can be set on the OUT message by the application/processor. The
value is the response code of the response message. If this header is not set, the
response code is set by the restlet runtime engine.
org.restlet.*
Attributes of a restlet message that get propagated to Camel IN headers.
Camel 2.x
Name
Type
Description
Content-Type
String
Specifies the content type, which can be set on the OUT message by the application/processor. The
value is the content-type of the response message. If this header is not set, the content type is based
on the object type of the OUT message body. In Camel 2.3 onward, if the Content-Type header is
specified in the Camel IN message, the value of the header determine the content type for the Restlet
request message. Otherwise, it is defaulted to "application/x-www-form-urlencoded'. Prior to release
2.3, it is not possible to change the request content type default.
CamelHttpMethod
String
The HTTP request method. This is set in the IN message header.
CamelHttpQuery
String
The query string of the request URI. It is set on the IN message by DefaultRestletBinding when the
restlet component receives a request.
CamelHttpResponseCode
String
or
Integer
The response code can be set on the OUT message by the application/processor. The value is the
response code of the response message. If this header is not set, the response code is set by the restlet
runtime engine.
CamelHttpUri
String
The HTTP request URI. This is set in the IN message header.
CamelRestletLogin
String
Login name for basic authentication. It is set on the IN message by the application and gets filtered
before the restlet request header by Camel.
CamelRestletPassword
String
Password name for basic authentication. It is set on the IN message by the application and gets filtered
before the restlet request header by Camel.
CamelRestletRequest
Request
Camel 2.8: The org.restlet.Request object which holds all request details.
CamelRestletResponse
Response
Camel 2.8: The org.restlet.Response object. You can use this to create responses using the API from
Restlet. See examples below.
org.restlet.*
Attributes of a Restlet message that get propagated to Camel IN headers.
Message Body
Camel will store the restlet response from the external server on the OUT
body. All headers from the IN message will be copied to the OUT message, so
that headers are preserved during routing.
Samples
Restlet Endpoint with Authentication
The following route starts a restlet consumer endpoint that listens for POST
requests on http://localhost:8080. The processor creates a response that
echoes the request body and the value of the id header.
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from("restlet:http://localhost:" + port +
"/securedOrders?restletMethod=post&restletRealm=#realm").process(new Processor() {
public void process(Exchange exchange) throws Exception {
exchange.getOut().setBody(
"received [" + exchange.getIn().getBody()
+ "] as an order id = "
+ exchange.getIn().getHeader("id"));
}
});
The restletRealm setting (in 2.x, use the # notation, that is,
restletRealm=#refName)in the URI query is used to look up a Realm Map in
the registry. If this option is specified, the restlet consumer uses the
information to authenticate user logins. Only authenticated requests can
access the resources. In this sample, we create a Spring application context
that serves as a registry. The bean ID of the Realm Map should match the
restletRealmRef.
The following sample starts a direct endpoint that sends requests to the
server on http://localhost:8080 (that is, our restlet consumer endpoint).
// Note: restletMethod and restletRealmRef are stripped
// from the query before a request is sent as they are
// only processed by Camel.
from("direct:start-auth").to("restlet:http://localhost:" + port +
"/securedOrders?restletMethod=post");
That is all we need. We are ready to send a request and try out the restlet
component:
final String id = "89531";
Map headers = new HashMap();
headers.put(RestletConstants.RESTLET_LOGIN, "admin");
headers.put(RestletConstants.RESTLET_PASSWORD, "foo");
headers.put("id", id);
String response = (String)template.requestBodyAndHeaders(
"direct:start-auth", "", headers);
The sample client sends a request to the direct:start-auth endpoint with
the following headers:
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• CamelRestletLogin (used internally by Camel)
• CamelRestletPassword (used internally by Camel)
• id (application header)
The sample client gets a response like the following:
received [] as an order id = 89531
Single restlet endpoint to service multiple methods and
URI templates (2.0 or later)
It is possible to create a single route to service multiple HTTP methods using
the restletMethods option. This snippet also shows how to retrieve the
request method from the header:
from("restlet:http://localhost:" + portNum + "/users/
{username}?restletMethods=post,get")
.process(new Processor() {
public void process(Exchange exchange) throws Exception {
// echo the method
exchange.getOut().setBody(exchange.getIn().getHeader(Exchange.HTTP_METHOD,
String.class));
}
});
In addition to servicing multiple methods, the next snippet shows how to
create an endpoint that supports multiple URI templates using the
restletUriPatterns option. The request URI is available in the header of
the IN message as well. If a URI pattern has been defined in the endpoint URI
(which is not the case in this sample), both the URI pattern defined in the
endpoint and the restletUriPatterns option will be honored.
from("restlet:http://localhost:" + portNum +
"?restletMethods=post,get&restletUriPatterns=#uriTemplates")
.process(new Processor() {
public void process(Exchange exchange) throws Exception {
// echo the method
String uri = exchange.getIn().getHeader(Exchange.HTTP_URI, String.class);
String out = exchange.getIn().getHeader(Exchange.HTTP_METHOD,
String.class);
if (("http://localhost:" + portNum + "/users/homer").equals(uri)) {
exchange.getOut().setBody(out + " " +
exchange.getIn().getHeader("username", String.class));
} else if (("http://localhost:" + portNum + "/atom/collection/foo/
component/bar").equals(uri)) {
exchange.getOut().setBody(out + " " +
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Note
org.apache.camel.restlet.auth.login and
org.apache.camel.restlet.auth.password will not be
propagated as Restlet header.
exchange.getIn().getHeader("id", String.class)
+ " " + exchange.getIn().getHeader("cid",
String.class));
}
}
});
The restletUriPatterns=#uriTemplates option references the
List bean defined in the Spring XML configuration.
/users/{username}/atom/collection/{id}/component/{cid}
Using Restlet API to populate response
Available as of Camel 2.8
You may want to use the org.restlet.Response API to populate the
response. This gives you full access to the Restlet API and fine grained
control of the response. See the route snippet below where we generate the
response from an inlined Camel Processor:
Listing 87. Generating response using Restlet Response API
from("restlet:http://localhost:" + portNum + "/users/{id}/like/{beer}")
.process(new Processor() {
public void process(Exchange exchange) throws Exception {
// the Restlet request should be available if neeeded
Request request =
exchange.getIn().getHeader(RestletConstants.RESTLET_REQUEST, Request.class);
assertNotNull("Restlet Request", request);
// use Restlet API to create the response
Response response =
exchange.getIn().getHeader(RestletConstants.RESTLET_RESPONSE, Response.class);
assertNotNull("Restlet Response", response);
response.setStatus(Status.SUCCESS_OK);
response.setEntity("Beer is Good",
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MediaType.TEXT_XML);
exchange.getOut().setBody(response);
}
});
Using the Restlet servlet within a webapp
Available as of Camel 2.8
There are three possible ways to configure a Restlet application within a
servlet container and using the subclassed SpringServerServlet enables
configuration within Camel by injecting the Restlet Component.
Use of the Restlet servlet within a servlet container enables routes to be
configured with relative paths in URIs (removing the restrictions of hardcoded absolute URIs) and for the hosting servlet container to handle
incoming requests (rather than have to spawn a separate server process on a
new port).
To configure, add the following to your camel-context.xml;
Request type : ${header.CamelHttpMethod} and ID : ${header.id}
And add this to your web.xml;
RestletServletorg.restlet.ext.spring.SpringServerServletorg.restlet.componentRestletComponent
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RestletServlet/rs/*
You will then be able to access the deployed route at http://localhost:8080/
mywebapp/rs/demo/1234 where;
localhost:8080 is the server and port of your servlet container
mywebapp is the name of your deployed webapp
Your browser will then show the following content;
"Request type : GET and ID : 1234"
You will need to add dependency on the Spring extension to restlet which you
can do in your Maven pom.xml file:
org.restlet.jeeorg.restlet.ext.spring${restlet-version}
And you would need to add dependency on the restlet maven repository as
well:
maven-restletPublic online Restlet repositoryhttp://maven.restlet.org
See Also
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•
•
•
Configuring Camel
Component
Endpoint
Getting Started
RMI COMPONENT
The rmi: component binds PojoExchanges to the RMI protocol (JRMP).
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Since this binding is just using RMI, normal RMI rules still apply regarding
what methods can be invoked. This component supports only PojoExchanges
that carry a method invocation from an interface that extends the Remote
interface. All parameters in the method should be either Serializable or
Remote objects.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-rmix.x.x
URI format
rmi://rmi-regisitry-host:rmi-registry-port/registry-path[?options]
For example:
rmi://localhost:1099/path/to/service
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Value
Description
method
null
As of Camel 1.3, you can set the name of the method to invoke.
remoteInterfaces
null
Its now possible to use this option from Camel 2.7: in the XML DSL. It can be a list of interface
names separated by comma.
Using
To call out to an existing RMI service registered in an RMI registry, create a
route similar to the following:
from("pojo:foo").to("rmi://localhost:1099/foo");
To bind an existing camel processor or service in an RMI registry, define an
RMI endpoint as follows:
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RmiEndpoint endpoint= (RmiEndpoint) endpoint("rmi://localhost:1099/bar");
endpoint.setRemoteInterfaces(ISay.class);
from(endpoint).to("pojo:bar");
Note that when binding an RMI consumer endpoint, you must specify the
Remote interfaces exposed.
In XML DSL you can do as follows from Camel 2.7 onwards:
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
RSS COMPONENT
Available as of Camel 2.0
The rss: component is used for polling RSS feeds. Camel will default poll
the feed every 60th seconds.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-rssx.x.x
Note: The component currently only supports polling (consuming) feeds.
URI format
rss:rssUri
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Using camel-rss in OSGi environment
Camel-rss uses ROME 1.0 and below. This library has class loading
issues in OSGi environment. We submitted issue 142 to ROME.
You can also find patched version in this repository. One thing you
have to change is version - patched version is marked as 1.0-osgi.
Where rssUri is the URI to the RSS feed to poll.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Property
Default
Description
splitEntries
true
If true, Camel splits a feed into its individual entries and returns each entry, poll by poll. For
example, if a feed contains seven entries, Camel returns the first entry on the first poll, the
second entry on the second poll, and so on. When no more entries are left in the feed, Camel
contacts the remote RSS URI to obtain a new feed. If false, Camel obtains a fresh feed on every
poll and returns all of the feed's entries.
filter
true
Use in combination with the splitEntries option in order to filter returned entries. By default,
Camel applies the UpdateDateFilter filter, which returns only new entries from the feed,
ensuring that the consumer endpoint never receives an entry more than once. The filter orders
the entries chronologically, with the newest returned last.
throttleEntries
true
Camel 2.5: Sets whether all entries identified in a single feed poll should be delivered
immediately. If true, only one entry is processed per consumer.delay. Only applicable when
splitEntries is set to true.
lastUpdate
null
Use in combination with the filter option to block entries earlier than a specific date/time (uses
the entry.updated timestamp). The format is: yyyy-MM-ddTHH:MM:ss. Example:
2007-12-24T17:45:59.
feedHeader
true
Specifies whether to add the ROME SyndFeed object as a header.
sortEntries
false
If splitEntries is true, this specifies whether to sort the entries by updated date.
consumer.delay
60000
Delay in milliseconds between each poll.
consumer.initialDelay
1000
Milliseconds before polling starts.
consumer.userFixedDelay
false
Set to true to use fixed delay between pools, otherwise fixed rate is used. See
ScheduledExecutorService in JDK for details.
Exchange data types
Camel initializes the In body on the Exchange with a ROME SyndFeed.
Depending on the value of the splitEntries flag, Camel returns either a
SyndFeed with one SyndEntry or a java.util.List of SyndEntrys.
Option
Value
Behavior
splitEntries
true
A single entry from the current feed is set in the exchange.
splitEntries
false
The entire list of entries from the current feed is set in the exchange.
Message Headers
Header
Description
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org.apache.camel.component.rss.feed
Camel 1.x: The entire SyncFeed object.
CamelRssFeed
Camel 2.0: The entire SyncFeed object.
RSS Dataformat
The RSS component ships with an RSS dataformat that can be used to
convert between String (as XML) and ROME RSS model objects.
• marshal = from ROME SyndFeed to XML String
• unmarshal = from XML String to ROME SyndFeed
A route using this would look something like this:
from("rss:file:src/test/data/
rss20.xml?splitEntries=false&consumer.delay=1000").marshal().rss().to("mock:marshal");
The purpose of this feature is to make it possible to use Camel's lovely builtin expressions for manipulating RSS messages. As shown below, an XPath
expression can be used to filter the RSS message:
// only entries with Camel in the title will get through the filter
from("rss:file:src/test/data/rss20.xml?splitEntries=true&consumer.delay=100")
.marshal().rss().filter().xpath("//item/
title[contains(.,'Camel')]").to("mock:result");
Filtering entries
You can filter out entries quite easily using XPath, as shown in the data
format section above. You can also exploit Camel's Bean Integration to
implement your own conditions. For instance, a filter equivalent to the XPath
example above would be:
// only entries with Camel in the title will get through the filter
from("rss:file:src/test/data/rss20.xml?splitEntries=true&consumer.delay=100").
filter().method("myFilterBean", "titleContainsCamel").to("mock:result");
The custom bean for this would be:
public static class FilterBean {
public boolean titleContainsCamel(@Body SyndFeed feed) {
SyndEntry firstEntry = (SyndEntry) feed.getEntries().get(0);
return firstEntry.getTitle().contains("Camel");
}
}
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See Also
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Unable
Configuring Camel
Component
Endpoint
Getting Started
Atom
to render {include} Couldn't find a page to include called: Scalate
SEDA COMPONENT
The seda: component provides asynchronous SEDA behavior, so that
messages are exchanged on a BlockingQueue and consumers are invoked in
a separate thread from the producer.
Note that queues are only visible within a single CamelContext. If you want
to communicate across CamelContext instances (for example,
communicating between Web applications), see the VM component.
This component does not implement any kind of persistence or recovery, if
the VM terminates while messages are yet to be processed. If you need
persistence, reliability or distributed SEDA, try using either JMS or ActiveMQ.
URI format
seda:someName[?options]
Where someName can be any string that uniquely identifies the endpoint
within the current CamelContext.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Description
The maximum size (= capacity of the number of messages it can max hold) of the SEDA
queue. The default value in Camel 2.2 or older is 1000. From Camel 2.3 onwards the size is
unbounded by default.
size
concurrentConsumers
1
Camel 1.6.1/2.0: Number of concurrent threads processing exchanges.
waitForTaskToComplete
IfReplyExpected
Camel 2.0: Option to specify whether the caller should wait for the async task to complete
or not before continuing. The following three options are supported: Always, Never or
IfReplyExpected. The first two values are self-explanatory. The last value,
IfReplyExpected, will only wait if the message is Request Reply based. The default option is
IfReplyExpected. See more information about Async messaging.
timeout
30000
Camel 2.0: Timeout in millis a seda producer will at most waiting for an async task to
complete. See waitForTaskToComplete and Async for more details. In Camel 2.2 you can
now disable timeout by using 0 or a negative value.
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Synchronous
The Direct component provides synchronous invocation of any
consumers when a producer sends a message exchange.
Camel 1.x - Same URI must be used for both producer and
consumer
An exactly identical SEDA endpoint URI must be used for both the
producer endpoint and the consumer endpoint. Otherwise Camel
will create a second SEDA endpoint, even thought the someName
portion of the URI is identical. For example:
from("direct:foo").to("seda:bar?concurrentConsumers=5");
from("seda:bar?concurrentConsumers=5").to("file://output");
Notice that we have to use the full URI including options in both the
producer and consumer.
In Camel 2.x this has been fixed so its the queue name that must match,
eg in this example we are using bar as the queue name.
multipleConsumers
false
Camel 2.2: Specifies whether multiple consumers is allowed or not. If enabled you can use
SEDA for a pubsub kinda style messaging. Send a message to a seda queue and have
multiple consumers receive a copy of the message.
limitConcurrentConsumers
true
Camel 2.3: Whether to limit the concurrentConsumers to maximum 500. If its configured
with a higher number an exception will be thrown. You can disable this check by turning this
option off.
blockWhenFull
false
Camel 2.9: Whether to block the current thread when sending a message to a SEDA
endpoint, and the SEDA queue is full (capacity hit). By default an exception will be thrown
stating the queue is full. By setting this option to true the caller thread will instead block
and wait until the message can be delivered to the SEDA queue.
Changes in Camel 2.0
In Camel 2.0 the SEDA component supports using Request Reply, where the
caller will wait for the Async route to complete. For instance:
from("mina:tcp://0.0.0.0:9876?textline=true&sync=true").to("seda:input");
from("seda:input").to("bean:processInput").to("bean:createResponse");
In the route above, we have a TCP listener on port 9876 that accepts
incoming requests. The request is routed to the seda:input queue. As it is a
Request Reply message, we wait for the response. When the consumer on
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the seda:input queue is complete, it copies the response to the original
message response.
Camel 1.x does not have this feature implemented, the SEDA queues in
Camel 1.x will never wait.
Concurrent consumers
By default, the SEDA endpoint uses a single consumer thread, but you can
configure it to use concurrent consumer threads. So instead of thread pools
you can use:
from("seda:stageName?concurrentConsumers=5").process(...)
Difference between thread pools and concurrent
consumers
The thread pool is a pool that can increase/shrink dynamically at runtime
depending on load, whereas the concurrent consumers are always fixed.
Thread pools
Be aware that adding a thread pool to a SEDA endpoint by doing something
like:
from("seda:stageName").thread(5).process(...)
Can wind up with two BlockQueues: one from the SEDA endpoint, and one
from the workqueue of the thread pool, which may not be what you want.
Instead, you might want to consider configuring a Direct endpoint with a
thread pool, which can process messages both synchronously and
asynchronously. For example:
from("direct:stageName").thread(5).process(...)
You can also directly configure number of threads that process messages on
a SEDA endpoint using the concurrentConsumers option.
Sample
In the route below we use the SEDA queue to send the request to this async
queue to be able to send a fire-and-forget message for further processing in
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Camel 2.0 - 2.2: Works only with 2 endpoints
Using Request Reply over SEDA or VM only works with 2 endpoints.
You cannot chain endpoints by sending to A -> B -> C etc. Only
between A -> B. The reason is the implementation logic is fairly
simple. To support 3+ endpoints makes the logic much more
complex to handle ordering and notification between the waiting
threads properly.
This has been improved in Camel 2.3 onwards, which allows you to chain
as many endpoints as you like.
another thread, and return a constant reply in this thread to the original
caller.
public void configure() throws Exception {
from("direct:start")
// send it to the seda queue that is async
.to("seda:next")
// return a constant response
.transform(constant("OK"));
from("seda:next").to("mock:result");
}
Here we send a Hello World message and expects the reply to be OK.
Object out = template.requestBody("direct:start", "Hello World");
assertEquals("OK", out);
The "Hello World" message will be consumed from the SEDA queue from
another thread for further processing. Since this is from a unit test, it will be
sent to a mock endpoint where we can do assertions in the unit test.
Using multipleConsumers
Available as of Camel 2.2
In this example we have defined two consumers and registered them as
spring beans.
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Since we have specified multipleConsumers=true on the seda foo
endpoint we can have those two consumers receive their own copy of the
message as a kind of pub-sub style messaging.
As the beans are part of an unit test they simply send the message to a
mock endpoint, but notice how we can use @Consume to consume from the
seda queue.
public class FooEventConsumer {
@EndpointInject(uri = "mock:result")
private ProducerTemplate destination;
@Consume(ref = "foo")
public void doSomething(String body) {
destination.sendBody("foo" + body);
}
}
Extracting queue information.
If you need it, you can also get information like queue size etc without using
JMX like this:
SedaEndpoint seda = context.getEndpoint("seda:xxxx");
int size = seda.getExchanges().size()
See Also
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•
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Configuring Camel
Component
Endpoint
Getting Started
VM
Direct
Async
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SERVLET COMPONENT
Available as of Camel 2.0
The servlet: component provides HTTP based endpoints for consuming
HTTP requests that arrive at a HTTP endpoint and this endpoint is bound to a
published Servlet.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-servletx.x.x
<\!-\- use the same version as your Camel core version \-->
URI format
servlet://relative_path[?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Value
Description
httpBindingRef
null
Reference to an org.apache.camel.component.http.HttpBinding in the Registry. A HttpBinding
implementation can be used to customize how to write a response.
matchOnUriPrefix
false
Whether or not the CamelServlet should try to find a target consumer by matching the URI prefix, if no
exact match is found.
servletName
CamelServlet
Specifies the servlet name that the servlet endpoint will bind to. This name should match the name you
define in web.xml file.
Message Headers
Camel will apply the same Message Headers as the HTTP component.
Camel will also populate all request.parameter and request.headers.
For example, if a client request has the URL, http://myserver/
myserver?orderid=123, the exchange will contain a header named orderid
with the value 123.
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Usage
You can only consume from endpoints generated by the Servlet component.
Therefore, it should only be used as input into your camel routes. To issue
HTTP requests against other HTTP endpoints, use the HTTP Component
Sample
In this sample, we define a route that exposes a HTTP service at
http://localhost:8080/camel/services/hello.
First, you need to publish the CamelHttpTransportServlet through the normal
Web Container, or OSGi Service.
Use the Web.xml file to publish the CamelHttpTransportServlet as follows:
CamelServletCamel Http Transport Servletorg.apache.camel.component.servlet.CamelHttpTransportServletCamelServlet/services/*
Then you can define your route as follows:
from("servlet:///hello?matchOnUriPrefix=true").process(new Processor() {
public void process(Exchange exchange) throws Exception {
String contentType = exchange.getIn().getHeader(Exchange.CONTENT_TYPE,
String.class);
String path = exchange.getIn().getHeader(Exchange.HTTP_PATH, String.class);
assertEquals("Get a wrong content type", CONTENT_TYPE, contentType);
// assert camel http header
String charsetEncoding =
exchange.getIn().getHeader(Exchange.HTTP_CHARACTER_ENCODING, String.class);
assertEquals("Get a wrong charset name from the message heaer", "UTF-8",
charsetEncoding);
// assert exchange charset
assertEquals("Get a wrong charset naem from the exchange property", "UTF-8",
exchange.getProperty(Exchange.CHARSET_NAME));
exchange.getOut().setHeader(Exchange.CONTENT_TYPE, contentType + ";
charset=UTF-8");
exchange.getOut().setHeader("PATH", path);
exchange.getOut().setBody("Hello World");
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From Camel 2.7 onwards its easier to use Servlet in Spring web
applications. See Servlet Tomcat Example for details.
}
});
Sample when using Spring 3.x
See Servlet Tomcat Example
Sample when using Spring 2.x
When using the Servlet component in a Camel/Spring application it's often
required to load the Spring ApplicationContext after the Servlet component
has started. This can be accomplished by using Spring's
ContextLoaderServlet instead of ContextLoaderListener. In that case
you'll need to start ContextLoaderServlet after CamelHttpTransportServlet
like this:
CamelServlet
org.apache.camel.component.servlet.CamelHttpTransportServlet
1SpringApplicationContext
org.springframework.web.context.ContextLoaderServlet
2
Sample when using OSGi
From Camel 2.6.0, you can publish the CamelHttpTransportServlet as an
OSGi service with help of SpringDM like this.
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Specify the relative path for camel-servlet endpoint
Since we are binding the Http transport with a published servlet,
and we don't know the servlet's application context path, the
camel-servlet endpoint uses the relative path to specify the
endpoint's URL. A client can access the camel-servlet endpoint
through the servlet publish address: ("http://localhost:8080/
camel/services") + RELATIVE_PATH("/hello").
javax.servlet.Servletorg.apache.camel.component.http.CamelServlet
Then use this service in your camel route like this:
For versions prior to Camel 2.6 you can use an Activator to publish the
CamelHttpTransportServlet on the OSGi platform
import java.util.Dictionary;
import java.util.Hashtable;
import
import
import
import
import
import
import
887
org.apache.camel.component.servlet.CamelHttpTransportServlet;
org.osgi.framework.BundleActivator;
org.osgi.framework.BundleContext;
org.osgi.framework.ServiceReference;
org.osgi.service.http.HttpContext;
org.osgi.service.http.HttpService;
org.slf4j.Logger;
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
import org.slf4j.LoggerFactory;
import org.springframework.osgi.context.BundleContextAware;
public final class ServletActivator implements BundleActivator, BundleContextAware {
private static final transient Logger LOG =
LoggerFactory.getLogger(ServletActivator.class);
private static boolean registerService;
/**
* HttpService reference.
*/
private ServiceReference httpServiceRef;
/**
* Called when the OSGi framework starts our bundle
*/
public void start(BundleContext bc) throws Exception {
registerServlet(bc);
}
/**
* Called when the OSGi framework stops our bundle
*/
public void stop(BundleContext bc) throws Exception {
if (httpServiceRef != null) {
bc.ungetService(httpServiceRef);
httpServiceRef = null;
}
}
protected void registerServlet(BundleContext bundleContext) throws Exception {
httpServiceRef =
bundleContext.getServiceReference(HttpService.class.getName());
if (httpServiceRef != null && !registerService) {
LOG.info("Register the servlet service");
final HttpService httpService =
(HttpService)bundleContext.getService(httpServiceRef);
if (httpService != null) {
// create a default context to share between registrations
final HttpContext httpContext =
httpService.createDefaultHttpContext();
// register the hello world servlet
final Dictionary initParams = new Hashtable();
initParams.put("matchOnUriPrefix", "false");
initParams.put("servlet-name", "CamelServlet");
httpService.registerServlet("/camel/services", // alias
new CamelHttpTransportServlet(), // register servlet
initParams, // init params
httpContext // http context
);
registerService = true;
}
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}
}
public void setBundleContext(BundleContext bc) {
try {
registerServlet(bc);
} catch (Exception e) {
LOG.error("Cannot register the servlet, the reason is " + e);
}
}
}
See Also
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Configuring Camel
Component
Endpoint
Getting Started
Servlet Tomcat Example
HTTP
Jetty
SHIRO SECURITY COMPONENT
Available as of Camel 2.5
The shiro-security component in Camel is a security focused component,
based on the Apache Shiro security project.
Apache Shiro is a powerful and flexible open-source security framework
that cleanly handles authentication, authorization, enterprise session
management and cryptography. The objective of the Apache Shiro project is
to provide the most robust and comprehensive application security
framework available while also being very easy to understand and extremely
simple to use.
This camel shiro-security component allows authentication and
authorization support to be applied to different segments of a camel route.
Shiro security is applied on a route using a Camel Policy. A Policy in Camel
utilizes a strategy pattern for applying interceptors on Camel Processors. It
offering the ability to apply cross-cutting concerns (for example. security,
transactions etc) on sections/segments of a camel route.
Maven users will need to add the following dependency to their pom.xml
for this component:
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org.apache.camelcamel-shirox.x.x
Shiro Security Basics
To employ Shiro security on a camel route, a ShiroSecurityPolicy object must
be instantiated with security configuration details (including users,
passwords, roles etc). This object must then be applied to a camel route. This
ShiroSecurityPolicy Object may also be registered in the Camel registry (JNDI
or ApplicationContextRegistry) and then utilized on other routes in the Camel
Context.
Configuration details are provided to the ShiroSecurityPolicy using an Ini
file (properties file) or an Ini object. The Ini file is a standard Shiro
configuration file containing user/role details as shown below
[users]
# user 'ringo' with password 'starr' and the 'sec-level1' role
ringo = starr, sec-level1
george = harrison, sec-level2
john = lennon, sec-level3
paul = mccartney, sec-level3
[roles]
# 'sec-level3' role has all permissions, indicated by the
# wildcard '*'
sec-level3 = *
# The 'sec-level2' role can do anything with access of permission
# readonly (*) to help
sec-level2 = zone1:*
# The 'sec-level1' role can do anything with access of permission
# readonly
sec-level1 = zone1:readonly:*
Instantiating a ShiroSecurityPolicy Object
A ShiroSecurityPolicy object is instantiated as follows
private final String iniResourcePath = "classpath:shiro.ini";
private final byte[] passPhrase = {
(byte) 0x08, (byte) 0x09, (byte) 0x0A, (byte) 0x0B,
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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(byte) 0x0C, (byte) 0x0D, (byte) 0x0E, (byte) 0x0F,
(byte) 0x10, (byte) 0x11, (byte) 0x12, (byte) 0x13,
(byte) 0x14, (byte) 0x15, (byte) 0x16, (byte) 0x17};
List permissionsList = new ArrayList();
Permission permission = new WildcardPermission("zone1:readwrite:*");
permissionsList.add(permission);
final ShiroSecurityPolicy securityPolicy =
new ShiroSecurityPolicy(iniResourcePath, passPhrase, true,
permissionsList);
ShiroSecurityPolicy Options
Name
Default
Value
Type
Description
iniResourcePath or
ini
none
Resource String or Ini Object
A mandatory Resource String for the iniResourcePath or an
instance of an Ini object must be passed to the security
policy. Resources can be acquired from the file system,
classpath, or URLs when prefixed with "file:, classpath:, or
url:" respectively. For e.g "classpath:shiro.ini"
passPhrase
An AES 128
based key
byte[]
A passPhrase to decrypt ShiroSecurityToken(s) sent along
with Message Exchanges
alwaysReauthenticate
true
boolean
Setting to ensure re-authentication on every individual
request. If set to false, the user is authenticated and locked
such than only requests from the same user going forward
are authenticated.
permissionsList
none
List
A List of permissions required in order for an authenticated
user to be authorized to perform further action i.e continue
further on the route. If no Permissions list is provided to the
ShiroSecurityPolicy object, then authorization is deemed as
not required
cipherService
AES
org.apache.shiro.crypto.CipherService
Shiro ships with AES & Blowfish based CipherServices. You
may use one these or pass in your own Cipher
implementation
Applying Shiro Authentication on a Camel Route
The ShiroSecurityPolicy, tests and permits incoming message exchanges
containing a encrypted SecurityToken in the Message Header to proceed
further following proper authentication. The SecurityToken object contains a
Username/Password details that are used to determine where the user is a
valid user.
protected RouteBuilder createRouteBuilder() throws Exception {
final ShiroSecurityPolicy securityPolicy =
new ShiroSecurityPolicy("classpath:shiro.ini", passPhrase);
return new RouteBuilder() {
public void configure() {
onException(UnknownAccountException.class).
to("mock:authenticationException");
onException(IncorrectCredentialsException.class).
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to("mock:authenticationException");
onException(LockedAccountException.class).
to("mock:authenticationException");
onException(AuthenticationException.class).
to("mock:authenticationException");
from("direct:secureEndpoint").
to("log:incoming payload").
policy(securityPolicy).
to("mock:success");
}
};
}
Applying Shiro Authorization on a Camel Route
Authorization can be applied on a camel route by associating a Permissions
List with the ShiroSecurityPolicy. The Permissions List specifies the
permissions necessary for the user to proceed with the execution of the route
segment. If the user does not have the proper permission set, the request is
not authorized to continue any further.
protected RouteBuilder createRouteBuilder() throws Exception {
final ShiroSecurityPolicy securityPolicy =
new ShiroSecurityPolicy("./src/test/resources/securityconfig.ini",
passPhrase);
return new RouteBuilder() {
public void configure() {
onException(UnknownAccountException.class).
to("mock:authenticationException");
onException(IncorrectCredentialsException.class).
to("mock:authenticationException");
onException(LockedAccountException.class).
to("mock:authenticationException");
onException(AuthenticationException.class).
to("mock:authenticationException");
from("direct:secureEndpoint").
to("log:incoming payload").
policy(securityPolicy).
to("mock:success");
}
};
}
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Creating a ShiroSecurityToken and injecting it into a Message
Exchange
A ShiroSecurityToken object may be created and injected into a Message
Exchange using a Shiro Processor called ShiroSecurityTokenInjector. An
example of injecting a ShiroSecurityToken using a ShiroSecurityTokenInjector
in the client is shown below
ShiroSecurityToken shiroSecurityToken = new ShiroSecurityToken("ringo", "starr");
ShiroSecurityTokenInjector shiroSecurityTokenInjector =
new ShiroSecurityTokenInjector(shiroSecurityToken, passPhrase);
from("direct:client").
process(shiroSecurityTokenInjector).
to("direct:secureEndpoint");
Sending Messages to routes secured by a ShiroSecurityPolicy
Messages and Message Exchanges sent along the camel route where the
security policy is applied need to be accompanied by a SecurityToken in the
Exchange Header. The SecurityToken is an encrypted object that holds a
Username and Password. The SecurityToken is encrypted using AES 128 bit
security by default and can be changed to any cipher of your choice.
Given below is an example of how a request may be sent using a
ProducerTemplate in Camel along with a SecurityToken
@Test
public void testSuccessfulShiroAuthenticationWithNoAuthorization() throws
Exception {
//Incorrect password
ShiroSecurityToken shiroSecurityToken = new ShiroSecurityToken("ringo",
"stirr");
// TestShiroSecurityTokenInjector extends ShiroSecurityTokenInjector
TestShiroSecurityTokenInjector shiroSecurityTokenInjector =
new TestShiroSecurityTokenInjector(shiroSecurityToken, passPhrase);
successEndpoint.expectedMessageCount(1);
failureEndpoint.expectedMessageCount(0);
template.send("direct:secureEndpoint", shiroSecurityTokenInjector);
successEndpoint.assertIsSatisfied();
failureEndpoint.assertIsSatisfied();
}
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SIP COMPONENT
Available as of Camel 2.5
The sip component in Camel is a communication component, based on
the Jain SIP implementation (available under the JCP license).
Session Initiation Protocol (SIP) is an IETF-defined signaling protocol,
widely used for controlling multimedia communication sessions such as voice
and video calls over Internet Protocol (IP).The SIP protocol is an Application
Layer protocol designed to be independent of the underlying transport layer;
it can run on Transmission Control Protocol (TCP), User Datagram Protocol
(UDP) or Stream Control Transmission Protocol (SCTP).
The Jain SIP implementation supports TCP and UDP only.
The Camel SIP component only supports the SIP Publish and Subscribe
capability as described in the RFC3903 - Session Initiation Protocol (SIP)
Extension for Event
This camel component supports both producer and consumer endpoints.
Camel SIP Producers (Event Publishers) and SIP Consumers (Event
Subscribers) communicate event & state information to each other using an
intermediary entity called a SIP Presence Agent (a stateful brokering entity).
For SIP based communication, a SIP Stack with a listener must be
instantiated on both the SIP Producer and Consumer (using separate ports if
using localhost). This is necessary in order to support the handshakes &
acknowledgements exchanged between the SIP Stacks during
communication.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-sipx.x.x
URI format
The URI scheme for a sip endpoint is as follows:
sip://johndoe@localhost:99999[?options]
sips://johndoe@localhost:99999/[?options]
This component supports producer and consumer endpoints for both TCP and
UDP.
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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You can append query options to the URI in the following format,
?option=value&option=value&...
Options
The SIP Component offers an extensive set of configuration options &
capability to create custom stateful headers needed to propagate state via
the SIP protocol.
Name
Default
Value
Description
stackName
NAME_NOT_SET
Name of the SIP Stack instance associated with an SIP Endpoint.
transport
tcp
Setting for choice of transport potocol. Valid choices are "tcp" or "udp".
fromUser
Username of the message originator. Mandatory setting unless a registry based custom
FromHeader is specified.
fromHost
Hostname of the message originator. Mandatory setting unless a registry based
FromHeader is specified
fromPort
Port of the message originator. Mandatory setting unless a registry based FromHeader is
specified
toUser
Username of the message receiver. Mandatory setting unless a registry based custom
ToHeader is specified.
toHost
Hostname of the message receiver. Mandatory setting unless a registry based ToHeader is
specified
toPort
Portname of the message receiver. Mandatory setting unless a registry based ToHeader is
specified
maxforwards
0
the number of intermediaries that may forward the message to the message receiver. Optional
setting. May alternatively be set using as registry based MaxForwardsHeader
eventId
Setting for a String based event Id. Mandatory setting unless a registry based FromHeader
is specified
eventHeaderName
Setting for a String based event Id. Mandatory setting unless a registry based FromHeader
is specified
maxMessageSize
1048576
Setting for maximum allowed Message size in bytes.
cacheConnections
false
Should connections be cached by the SipStack to reduce cost of connection creation. This is useful
if the connection is used for long running conversations.
consumer
false
This setting is used to determine whether the kind of header (FromHeader,ToHeader etc) that
needs to be created for this endpoint
automaticDialogSupport
off
Setting to specify whether every communication should be associated with a dialog.
contentType
text
Setting for contentType can be set to any valid MimeType.
contentSubType
xml
Setting for contentSubType can be set to any valid MimeSubType.
receiveTimeoutMillis
10000
Setting for specifying amount of time to wait for a Response and/or Acknowledgement can be
received from another SIP stack
useRouterForAllUris
false
This setting is used when requests are sent to the Presence Agent via a proxy.
msgExpiration
3600
The amount of time a message received at an endpoint is considered valid
presenceAgent
false
This setting is used to distingish between a Presence Agent & a consumer. This is due to the fact
that the SIP Camel component ships with a basic Presence Agent (for testing purposes only).
Consumers have to set this flag to true.
Registry based Options
SIP requires a number of headers to be sent/received as part of a request.
These SIP header can be enlisted in the Registry, such as in the Spring XML
file.
The values that could be passed in, are the following:
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Name
Description
fromHeader
a custom Header object containing message originator settings. Must implement the type javax.sip.header.FromHeader
toHeader
a custom Header object containing message receiver settings. Must implement the type javax.sip.header.ToHeader
viaHeaders
List of custom Header objects of the type javax.sip.header.ViaHeader. Each ViaHeader containing a proxy address for
request forwarding. (Note this header is automatically updated by each proxy when the request arrives at its listener)
contentTypeHeader
a custom Header object containing message content details. Must implement the type
javax.sip.header.ContentTypeHeader
callIdHeader
a custom Header object containing call details. Must implement the type javax.sip.header.CallIdHeader
maxForwardsHeader
a custom Header object containing details on maximum proxy forwards. This header places a limit on the viaHeaders
possible. Must implement the type javax.sip.header.MaxForwardsHeader
eventHeader
a custom Header object containing event details. Must implement the type javax.sip.header.EventHeader
contactHeader
an optional custom Header object containing verbose contact details (email, phone number etc). Must implement the
type javax.sip.header.ContactHeader
expiresHeader
a custom Header object containing message expiration details. Must implement the type javax.sip.header.ExpiresHeader
extensionHeader
a custom Header object containing user/application specific details. Must implement the type
javax.sip.header.ExtensionHeader
Sending Messages to/from a SIP endpoint
Creating a Camel SIP Publisher
In the example below, a SIP Publisher is created to send SIP Event
publications to
a user "agent@localhost:5152". This is the address of the SIP Presence Agent
which acts as a broker between the SIP Publisher and Subscriber
• using a SIP Stack named client
• using a registry based eventHeader called evtHdrName
• using a registry based eventId called evtId
• from a SIP Stack with Listener set up as user2@localhost:3534
• The Event being published is EVENT_A
• A Mandatory Header called REQUEST_METHOD is set to
Request.Publish thereby setting up the endpoint as a Event
publisher"
producerTemplate.sendBodyAndHeader(
"sip://agent@localhost:5152?stackName=client&eventHeaderName=evtHdrName&eventId=evtid&fromUser=user2&f
"EVENT_A",
"REQUEST_METHOD",
Request.PUBLISH);
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Creating a Camel SIP Subscriber
In the example below, a SIP Subscriber is created to receive SIP Event
publications sent to
a user "johndoe@localhost:5154"
• using a SIP Stack named Subscriber
• registering with a Presence Agent user called agent@localhost:5152
• using a registry based eventHeader called evtHdrName. The
evtHdrName contains the Event which is se to "Event_A"
• using a registry based eventId called evtId
@Override
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
// Create PresenceAgent
from("sip://agent@localhost:5152?stackName=PresenceAgent&presenceAgent=true&eventHeaderName=evtHdrName
.to("mock:neverland");
// Create Sip Consumer(Event Subscriber)
from("sip://johndoe@localhost:5154?stackName=Subscriber&toUser=agent&toHost=localhost&toPort=5152&even
.to("log:ReceivedEvent?level=DEBUG")
.to("mock:notification");
}
};
}
The Camel SIP component also ships with a Presence Agent that is
meant to be used for Testing and Demo purposes only. An example of
instantiating a Presence Agent is given above.
Note that the Presence Agent is set up as a user agent@localhost:5152
and is capable of communicating with both Publisher as well as Subscriber. It
has a separate SIP stackName distinct from Publisher as well as Subscriber.
While it is set up as a Camel Consumer, it does not actually send any
messages along the route to the endpoint "mock:neverland".
SMPP COMPONENT
Available as of Camel 2.2
This component provides access to an SMSC (Short Message Service
Center) over the SMPP protocol to send and receive SMS. The JSMPP is used.
Starting with Camel 2.9, you are also able to execute ReplaceSm,
QuerySm, SubmitMulti, CancelSm and DataSm.
897
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-smppx.x.x
URI format
smpp://[username@]hostname[:port][?options]
smpps://[username@]hostname[:port][?options]
If no username is provided, then Camel will provide the default value
smppclient.
If no port number is provided, then Camel will provide the default value
2775.
Camel 2.3: If the protocol name is "smpps", camel-smpp with try to use
SSLSocket to init a connection to the server.
You can append query options to the URI in the following format,
?option=value&option=value&...
URI Options
Name
Default
Value
Description
password
password
Specifies the password to use to log in to the SMSC.
systemType
cp
This parameter is used to categorize the type of ESME (External Short Message Entity) that is
binding to the SMSC (max. 13 characters).
dataCoding
0
Camel 2.5 onwarts until Camel 2.8.x Defines encoding of data according the SMPP 3.4
specification, section 5.2.19. Example data encodings are:
0: SMSC Default Alphabet
4: 8 bit Alphabet
8: UCS2 Alphabet
alphabet
0
Camel 2.9 onwarts Defines the alphabet of the data according the SMPP 3.4 specification,
section 5.2.19. Example alphabet encodings are:
-1: The SMPP component will try to determine the actual alphabet to be used. The message will be
sent using UCS2 encoding if it contains non standard GSM characters.
0: SMSC Default Alphabet
4: 8 bit Alphabet
8: UCS2 Alphabet
encoding
ISO-8859-1
only for SubmitSm, ReplaceSm and SubmitMulti Defines the encoding scheme of the short
message user data.
enquireLinkTimer
5000
Defines the interval in milliseconds between the confidence checks. The confidence check is used
to test the communication path between an ESME and an SMSC.
transactionTimer
10000
Defines the maximum period of inactivity allowed after a transaction, after which an SMPP entity
may assume that the session is no longer active. This timer may be active on either
communicating SMPP entity (i.e. SMSC or ESME).
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initialReconnectDelay
5000
Defines the initial delay in milliseconds after the consumer/producer tries to reconnect to the
SMSC, after the connection was lost.
reconnectDelay
5000
Defines the interval in milliseconds between the reconnect attempts, if the connection to the SMSC
was lost and the previous was not succeed.
1
only for SubmitSm, ReplaceSm, SubmitMulti and DataSm Is used to request an SMSC
delivery receipt and/or SME originated acknowledgements. The following values are defined:
0: No SMSC delivery receipt requested.
1: SMSC delivery receipt requested where final delivery outcome is success or failure.
2: SMSC delivery receipt requested where the final delivery outcome is delivery failure.
serviceType
CMT
The service type parameter can be used to indicate the SMS Application service associated with
the message. The following generic service_types are defined:
CMT: Cellular Messaging
CPT: Cellular Paging
VMN: Voice Mail Notification
VMA: Voice Mail Alerting
WAP: Wireless Application Protocol
USSD: Unstructured Supplementary Services Data
sourceAddr
1616
Defines the address of SME (Short Message Entity) which originated this message.
destAddr
1717
only for SubmitSm, SubmitMulti, CancelSm and DataSm Defines the destination SME
address. For mobile terminated messages, this is the directory number of the recipient MS.
0
Defines the type of number (TON) to be used in the SME originator address parameters. The
following TON values are defined:
0: Unknown
1: International
2: National
3: Network Specific
4: Subscriber Number
5: Alphanumeric
6: Abbreviated
0
only for SubmitSm, SubmitMulti, CancelSm and DataSm Defines the type of number (TON)
to be used in the SME destination address parameters. The following TON values are defined:
0: Unknown
1: International
2: National
3: Network Specific
4: Subscriber Number
5: Alphanumeric
6: Abbreviated
0
Defines the numeric plan indicator (NPI) to be used in the SME originator address parameters. The
following NPI values are defined:
0: Unknown
1: ISDN (E163/E164)
2: Data (X.121)
3: Telex (F.69)
6: Land Mobile (E.212)
8: National
9: Private
10: ERMES
13: Internet (IP)
18: WAP Client Id (to be defined by WAP Forum)
0
only for SubmitSm, SubmitMulti, CancelSm and DataSm Defines the numeric plan indicator
(NPI) to be used in the SME destination address parameters. The following NPI values are defined:
0: Unknown
1: ISDN (E163/E164)
2: Data (X.121)
3: Telex (F.69)
6: Land Mobile (E.212)
8: National
9: Private
10: ERMES
13: Internet (IP)
18: WAP Client Id (to be defined by WAP Forum)
1
only for SubmitSm and SubmitMulti Allows the originating SME to assign a priority level to the
short message. Four Priority Levels are supported:
0: Level 0 (lowest) priority
1: Level 1 priority
2: Level 2 priority
3: Level 3 (highest) priority
0
only for SubmitSm and SubmitMulti Used to request the SMSC to replace a previously
submitted message, that is still pending delivery. The SMSC will replace an existing message
provided that the source address, destination address and service type match the same fields in
the new message. The following replace if present flag values are defined:
0: Don't replace
1: Replace
registeredDelivery
sourceAddrTon
destAddrTon
sourceAddrNpi
destAddrNpi
priorityFlag
replaceIfPresentFlag
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0
Defines the type of number (TON) to be used in the SME. The following TON values are defined:
0: Unknown
1: International
2: National
3: Network Specific
4: Subscriber Number
5: Alphanumeric
6: Abbreviated
numberingPlanIndicator
0
Defines the numeric plan indicator (NPI) to be used in the SME. The following NPI values are
defined:
0: Unknown
1: ISDN (E163/E164)
2: Data (X.121)
3: Telex (F.69)
6: Land Mobile (E.212)
8: National
9: Private
10: ERMES
13: Internet (IP)
18: WAP Client Id (to be defined by WAP Forum)
lazySessionCreation
false
Camel 2.8 onwarts Sessions can be lazily created to avoid exceptions, if the SMSC is not
available when the Camel producer is started.
typeOfNumber
You can have as many of these options as you like.
smpp://smppclient@localhost:2775?password=password&enquireLinkTimer=3000&transactionTimer=5000&systemT
Message Headers
The following message headers can be used to affect the behavior of the
SMPP producer
Header
Description
CamelSmppDestAddr
only for SubmitSm, SubmitMulti, CancelSm and DataSm Defines the destination SME address. For
mobile terminated messages, this is the directory number of the recipient MS.
CamelSmppDestAddrTon
only for SubmitSm, SubmitMulti, CancelSm and DataSm Defines the type of number (TON) to be
used in the SME destination address parameters. The following TON values are defined:
0: Unknown
1: International
2: National
3: Network Specific
4: Subscriber Number
5: Alphanumeric
6: Abbreviated
CamelSmppDestAddrNpi
only for SubmitSm, SubmitMulti, CancelSm and DataSm Defines the numeric plan indicator (NPI) to
be used in the SME destination address parameters. The following NPI values are defined:
0: Unknown
1: ISDN (E163/E164)
2: Data (X.121)
3: Telex (F.69)
6: Land Mobile (E.212)
8: National
9: Private
10: ERMES
13: Internet (IP)
18: WAP Client Id (to be defined by WAP Forum)
CamelSmppSourceAddr
Defines the address of SME (Short Message Entity) which originated this message.
CamelSmppSourceAddrTon
Defines the type of number (TON) to be used in the SME originator address parameters. The following TON
values are defined:
0: Unknown
1: International
2: National
3: Network Specific
4: Subscriber Number
5: Alphanumeric
6: Abbreviated
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CamelSmppSourceAddrNpi
Defines the numeric plan indicator (NPI) to be used in the SME originator address parameters. The
following NPI values are defined:
0: Unknown
1: ISDN (E163/E164)
2: Data (X.121)
3: Telex (F.69)
6: Land Mobile (E.212)
8: National
9: Private
10: ERMES
13: Internet (IP)
18: WAP Client Id (to be defined by WAP Forum)
CamelSmppServiceType
The service type parameter can be used to indicate the SMS Application service associated with the
message. The following generic service_types are defined:
CMT: Cellular Messaging
CPT: Cellular Paging
VMN: Voice Mail Notification
VMA: Voice Mail Alerting
WAP: Wireless Application Protocol
USSD: Unstructured Supplementary Services Data
CamelSmppRegisteredDelivery
only for SubmitSm, ReplaceSm, SubmitMulti and DataSm Is used to request an SMSC delivery
receipt and/or SME originated acknowledgements. The following values are defined:
0: No SMSC delivery receipt requested.
1: SMSC delivery receipt requested where final delivery outcome is success or failure.
2: SMSC delivery receipt requested where the final delivery outcome is delivery failure.
CamelSmppPriorityFlag
only for SubmitSm and SubmitMulti Allows the originating SME to assign a priority level to the short
message. Four Priority Levels are supported:
0: Level 0 (lowest) priority
1: Level 1 priority
2: Level 2 priority
3: Level 3 (highest) priority
CamelSmppScheduleDeliveryTime
only for SubmitSm, SubmitMulti and ReplaceSm This parameter specifies the scheduled time at
which the message delivery should be first attempted. It defines either the absolute date and time or
relative time from the current SMSC time at which delivery of this message will be attempted by the SMSC.
It can be specified in either absolute time format or relative time format. The encoding of a time format is
specified in chapter 7.1.1. in the smpp specification v3.4.
CamelSmppValidityPeriod
only for SubmitSm, SubmitMulti and ReplaceSm The validity period parameter indicates the SMSC
expiration time, after which the message should be discarded if not delivered to the destination. It can be
defined in absolute time format or relative time format. The encoding of absolute and relative time format
is specified in chapter 7.1.1 in the smpp specification v3.4.
CamelSmppReplaceIfPresentFlag
only for SubmitSm and SubmitMulti The replace if present flag parameter is used to request the SMSC
to replace a previously submitted message, that is still pending delivery. The SMSC will replace an existing
message provided that the source address, destination address and service type match the same fields in
the new message. The following values are defined:
0: Don't replace
1: Replace
CamelSmppDataCoding
Camel 2.5 onwarts until Camel 2.8.x The data coding according to the SMPP 3.4 specification, section
5.2.19:
0: SMSC Default Alphabet
4: 8 bit Alphabet
8: UCS2 Alphabet
CamelSmppAlphabet
Camel 2.9 onwarts only for SubmitSm, SubmitMulti and ReplaceSm The data coding according to
the SMPP 3.4 specification, section 5.2.19:
-1: The SMPP component will try to determine the actual alphabet to be used. The message will be sent
using UCS2 encoding if it contains non standard GSM characters.
0: SMSC Default Alphabet
4: 8 bit Alphabet
8: UCS2 Alphabet
The following message headers are used by the SMPP producer to set the
response from the SMSC in the message header
901
Header
Description
CamelSmppId
The id to identify the submitted short message(s) for later use (delivery receipt, query sm, cancel sm, replace
sm). From Camel 2.9: In case of a ReplaceSm, QuerySm, CancelSm and DataSm, this header vaule is a
String. In case of a SubmitSm or SubmitMultiSm this header vaule is a String[].
CamelSmppSentMessageCount
From Camel 2.9 onwarts only for SubmitSm and SubmitMultiSm The total number of messages which
has been sent.
CamelSmppError
From Camel 2.9 onwarts only for SubmitMultiSm The errors which occurred by sending the short
message(s) the form Map>> (messageID : (destAddr : address, error :
errorCode)).
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
The following message headers are used by the SMPP consumer to set the
request data from the SMSC in the message header
Header
Description
CamelSmppSequenceNumber
only for AlertNotification, DeliverSm and DataSm A sequence number allows a response PDU to be
correlated with a request PDU. The associated SMPP response PDU must preserve this field.
CamelSmppCommandId
only for AlertNotification, DeliverSm and DataSm The command id field identifies the particular SMPP
PDU. For the complete list of defined values see chapter 5.1.2.1 in the smpp specification v3.4.
CamelSmppSourceAddr
only for AlertNotification, DeliverSm and DataSm Defines the address of SME (Short Message Entity)
which originated this message.
CamelSmppSourceAddrNpi
only for AlertNotification and DataSm Defines the numeric plan indicator (NPI) to be used in the SME
originator address parameters. The following NPI values are defined:
0: Unknown
1: ISDN (E163/E164)
2: Data (X.121)
3: Telex (F.69)
6: Land Mobile (E.212)
8: National
9: Private
10: ERMES
13: Internet (IP)
18: WAP Client Id (to be defined by WAP Forum)
CamelSmppSourceAddrTon
only for AlertNotification and DataSm Defines the type of number (TON) to be used in the SME
originator address parameters. The following TON values are defined:
0: Unknown
1: International
2: National
3: Network Specific
4: Subscriber Number
5: Alphanumeric
6: Abbreviated
CamelSmppEsmeAddr
only for AlertNotification Defines the destination ESME address. For mobile terminated messages, this is
the directory number of the recipient MS.
CamelSmppEsmeAddrNpi
only for AlertNotification Defines the numeric plan indicator (NPI) to be used in the ESME originator
address parameters. The following NPI values are defined:
0: Unknown
1: ISDN (E163/E164)
2: Data (X.121)
3: Telex (F.69)
6: Land Mobile (E.212)
8: National
9: Private
10: ERMES
13: Internet (IP)
18: WAP Client Id (to be defined by WAP Forum)
CamelSmppEsmeAddrTon
only for AlertNotification Defines the type of number (TON) to be used in the ESME originator address
parameters. The following TON values are defined:
0: Unknown
1: International
2: National
3: Network Specific
4: Subscriber Number
5: Alphanumeric
6: Abbreviated
CamelSmppId
only for smsc DeliveryReceipt and DataSm The message ID allocated to the message by the SMSC
when originally submitted.
CamelSmppDelivered
only for smsc DeliveryReceipt Number of short messages delivered. This is only relevant where the
original message was submitted to a distribution list.The value is padded with leading zeros if necessary.
CamelSmppDoneDate
only for smsc DeliveryReceipt The time and date at which the short message reached it's final state.
The format is as follows: YYMMDDhhmm.
CamelSmppStatus
only for smsc DeliveryReceipt and DataSm The final status of the message. The following values are
defined:
DELIVRD: Message is delivered to destination
EXPIRED: Message validity period has expired.
DELETED: Message has been deleted.
UNDELIV: Message is undeliverable
ACCEPTD: Message is in accepted state (i.e. has been manually read on behalf of the subscriber by
customer service)
UNKNOWN: Message is in invalid state
REJECTD: Message is in a rejected state
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902
CamelSmppError
only for smsc DeliveryReceipt Where appropriate this may hold a Network specific error code or an
SMSC error code for the attempted delivery of the message. These errors are Network or SMSC specific and
are not included here.
CamelSmppSubmitDate
only for smsc DeliveryReceipt The time and date at which the short message was submitted. In the
case of a message which has been replaced, this is the date that the original message was replaced. The
format is as follows: YYMMDDhhmm.
CamelSmppSubmitted
only for smsc DeliveryReceipt Number of short messages originally submitted. This is only relevant
when the original message was submitted to a distribution list.The value is padded with leading zeros if
necessary.
CamelSmppDestAddr
only for DeliverSm and DataSm Defines the destination SME address. For mobile terminated messages,
this is the directory number of the recipient MS.
CamelSmppScheduleDeliveryTime
only for DeliverSm and DataSm This parameter specifies the scheduled time at which the message
delivery should be first attempted. It defines either the absolute date and time or relative time from the
current SMSC time at which delivery of this message will be attempted by the SMSC. It can be specified in
either absolute time format or relative time format. The encoding of a time format is specified in Section
7.1.1. in the smpp specification v3.4.
CamelSmppValidityPeriod
only for DeliverSm The validity period parameter indicates the SMSC expiration time, after which the
message should be discarded if not delivered to the destination. It can be defined in absolute time format
or relative time format. The encoding of absolute and relative time format is specified in Section 7.1.1 in
the smpp specification v3.4.
CamelSmppServiceType
only for DeliverSm and DataSm The service type parameter indicates the SMS Application service
associated with the message.
CamelSmppRegisteredDelivery
only for DataSm Is used to request an delivery receipt and/or SME originated acknowledgements. The
following values are defined:
0: No SMSC delivery receipt requested.
1: SMSC delivery receipt requested where final delivery outcome is success or failure.
2: SMSC delivery receipt requested where the final delivery outcome is delivery failure.
CamelSmppDestAddrNpi
only for DataSm Defines the numeric plan indicator (NPI) in the destination address parameters. The
following NPI values are defined:
0: Unknown
1: ISDN (E163/E164)
2: Data (X.121)
3: Telex (F.69)
6: Land Mobile (E.212)
8: National
9: Private
10: ERMES
13: Internet (IP)
18: WAP Client Id (to be defined by WAP Forum)
CamelSmppDestAddrTon
only for DataSm Defines the type of number (TON) in the destination address parameters. The following
TON values are defined:
0: Unknown
1: International
2: National
3: Network Specific
4: Subscriber Number
5: Alphanumeric
6: Abbreviated
CamelSmppMessageType
Camel 2.6 onwarts: Identifies the type of an incoming message:
AlertNotification: an SMSC alert notification
DataSm: an SMSC data short message
DeliveryReceipt: an SMSC delivery receipt
DeliverSm: an SMSC deliver short message
Exception handling
This component supports the general Camel exception handling capabilities.
Camel 2.8 onwarts: When the SMPP consumer receives a DeliverSm or
DataSm short message and the processing of these messages fails, you can
also throw a ProcessRequestException instead of handle the failure. In this
case, this exception is forwarded to the underlying JSMPP library which will
return the included error code to the SMSC. This feature is useful to e.g.
instruct the SMSC to resend the short message at a later time. This could be
done with the following lines of code:
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CH AP T E R 11 - C OM P ON E N T A P P E N DIX
JSMPP library
See the documentation of the JSMPP Library for more details about
the underlying library.
from("smpp://smppclient@localhost:2775?password=password&enquireLinkTimer=3000&transactionTimer=5000&s
.doTry()
.to("bean:dao?method=updateSmsState")
.doCatch(Exception.class)
.throwException(new ProcessRequestException("update of sms state failed", 100))
.end();
Please refer to the SMPP specification for the complete list of error codes and
their meanings.
Samples
A route which sends an SMS using the Java DSL:
from("direct:start")
.to("smpp://smppclient@localhost:2775?
password=password&enquireLinkTimer=3000&transactionTimer=5000&systemType=producer");
A route which sends an SMS using the Spring XML DSL:
A route which receives an SMS using the Java DSL:
from("smpp://smppclient@localhost:2775?password=password&enquireLinkTimer=3000&transactionTimer=5000&s
.to("bean:foo");
A route which receives an SMS using the Spring XML DSL:
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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Debug logging
This component has log level DEBUG, which can be helpful in debugging
problems. If you use log4j, you can add the following line to your
configuration:
log4j.logger.org.apache.camel.component.smpp=DEBUG
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
SNMP COMPONENT
Available as of Camel 2.1
The snmp: component gives you the ability to poll SNMP capable devices
or receiving traps.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-snmpx.x.x
URI format
snmp://hostname[:port][?Options]
The component supports polling OID values from an SNMP enabled device
and receiving traps.
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CH AP T E R 11 - C OM P ON E N T A P P E N DIX
SMSC simulator
If you need an SMSC simulator for your test, you can use the
simulator provided by Logica.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Value
Description
type
none
The type of action you want to perform. Actually you can enter here POLL or TRAP. The value POLL will instruct
the endpoint to poll a given host for the supplied OID keys. If you put in TRAP you will setup a listener for
SNMP Trap Events.
address
none
This is the IP address and the port of the host to poll or where to setup the Trap Receiver. Example:
127.0.0.1:162
protocol
udp
Here you can select which protocol to use. You can use either udp or tcp.
retries
2
Defines how often a retry is made before canceling the request.
timeout
1500
Sets the timeout value for the request in millis.
snmpVersion
0 (which
means
SNMPv1)
Sets the snmp version for the request.
snmpCommunity
public
Sets the community octet string for the snmp request.
delay
60 seconds
Defines the delay in seconds between to poll cycles.
oids
none
Defines which values you are interested in. Please have a look at the Wikipedia to get a better understanding.
You may provide a single OID or a coma separated list of OIDs. Example:
oids="1.3.6.1.2.1.1.3.0,1.3.6.1.2.1.25.3.2.1.5.1,1.3.6.1.2.1.25.3.5.1.1.1,1.3.6.1.2.1.43.5.1.1.11.1"
The result of a poll
Given the situation, that I poll for the following OIDs:
Listing 88. OIDs
1.3.6.1.2.1.1.3.0
1.3.6.1.2.1.25.3.2.1.5.1
1.3.6.1.2.1.25.3.5.1.1.1
1.3.6.1.2.1.43.5.1.1.11.1
The result will be the following:
Listing 89. Result of toString conversion
1.3.6.1.2.1.1.3.06 days, 21:14:28.00
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1.3.6.1.2.1.25.3.2.1.5.121.3.6.1.2.1.25.3.5.1.1.131.3.6.1.2.1.43.5.1.1.11.161.3.6.1.2.1.1.1.0My Very Special Printer Of Brand Unknown
As you maybe recognized there is one more result than
requested....1.3.6.1.2.1.1.1.0.
This one is filled in by the device automatically in this special case. So it may
absolutely happen, that you receive more than you requested...be prepared.
Examples
Polling a remote device:
snmp:192.168.178.23:161?protocol=udp&type=POLL&oids=1.3.6.1.2.1.1.5.0
Setting up a trap receiver (Note that no OID info is needed here!):
snmp:127.0.0.1:162?protocol=udp&type=TRAP
Routing example in Java: (converts the SNMP PDU to XML String)
from("snmp:192.168.178.23:161?protocol=udp&type=POLL&oids=1.3.6.1.2.1.1.5.0").
convertBodyTo(String.class).
to("activemq:snmp.states");
See Also
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•
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•
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Endpoint
Getting Started
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
SPRING INTEGRATION COMPONENT
The spring-integration: component provides a bridge for Camel
components to talk to spring integration endpoints.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-spring-integrationx.x.x
URI format
spring-integration:defaultChannelName[?options]
Where defaultChannelName represents the default channel name which is
used by the Spring Integration Spring context. It will equal to the
inputChannel name for the Spring Integration consumer and the
outputChannel name for the Spring Integration provider.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Type
Description
inputChannel
String
The Spring integration input channel name that this endpoint wants to consume from, where the specified channel
name is defined in the Spring context.
outputChannel
String
The Spring integration output channel name that is used to send messages to the Spring integration context.
inOut
String
The exchange pattern that the Spring integration endpoint should use. If inOut=true then a reply channel is
expected, either from the Spring Integration Message header or configured on the endpoint.
Usage
The Spring integration component is a bridge that connects Camel endpoints
with Spring integration endpoints through the Spring integration's input
channels and output channels. Using this component, we can send Camel
messages to Spring Integration endpoints or receive messages from Spring
integration endpoints in a Camel routing context.
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Examples
Using the Spring integration endpoint
You can set up a Spring integration endpoint using a URI, as follows:
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Or directly using a Spring integration channel name:
The Source and Target adapter
Spring integration also provides the Spring integration's source and target
adapters, which can route messages from a Spring integration channel to a
Camel endpoint or from a Camel endpoint to a Spring integration channel.
This example uses the following namespaces:
You can bind your source or target to a Camel endpoint as follows:
camelTargetContextcamelTargetContextcamelTargetContext
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camelSourceContextcamelSourceContext
See Also
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•
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•
Configuring Camel
Component
Endpoint
Getting Started
SPRING WEB SERVICES COMPONENT
Available as of Camel 2.6
The spring-ws: component allows you to integrate with Spring Web
Services. It offers both client-side support, for accessing web services, and
server-side support for creating your own contract-first web services.
Maven users will need to add the following dependency to their pom.xml
for this component:
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org.apache.camelcamel-spring-wsx.x.x
URI format
The URI scheme for this component is as follows
spring-ws:[mapping-type:]address[?options]
To expose a web service mapping-type needs to be set to any of the
following:
Mapping
type
Description
rootqname
Offers the option to map web service requests based on the qualified name of the root element contained in the message.
soapaction
Used to map web service requests based on the SOAP action specified in the header of the message.
uri
In order to map web service requests that target a specific URI.
xpathresult
Used to map web service requests based on the evaluation of an XPath expression against the incoming message. The
result of the evaluation should match the XPath result specified in the endpoint URI.
beanname
Allows you to reference a org.apache.camel.component.spring.ws.bean.CamelEndpointDispatcher in order to integrate
with existing (legacy) endpoint mappings like PayloadRootQNameEndpointMapping, SoapActionEndpointMapping, etc
As a consumer the address should contain a value relevant to the specified
mapping-type (e.g. a SOAP action, XPath expression). As a producer the
address should be set to the URI of the web service your calling upon.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Required?
Description
soapAction
No
SOAP action to include inside a SOAP request when accessing remote web services
wsAddressingAction
No
WS-Addressing 1.0 action header to include when accessing web services. The To header is set to
the address of the web service as specified in the endpoint URI (default Spring-WS behavior).
expression
Only when
mapping-type is
xpathresult
XPath expression to use in the process of mapping web service requests, should match the result
specified by xpathresult
Registry based options
The following options can be specified in the registry (most likely a Spring
ApplicationContext) and referenced from the endpoint URI using the #
notation.
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Dependencies
As of Camel 2.8 this component ships with Spring-WS 2.0.x which
(like the rest of Camel) requires Spring 3.0.x.
Earlier Camel versions shipped Spring-WS 1.5.9 which is compatible with
Spring 2.5.x and 3.0.x. In order to run earlier versions of camel-spring-ws
on Spring 2.5.x you need to add the spring-webmvc module from Spring
2.5.x. In order to run Spring-WS 1.5.9 on Spring 3.0.x you need to exclude
the OXM module from Spring 3.0.x as this module is also included in
Spring-WS 1.5.9 (see this post)
Name
Required?
Description
webServiceTemplate
No
Option to provide a custom WebServiceTemplate. This allows for full control over client-side web
services handling; like adding a custom interceptor or specifying a fault resolver, message sender
or message factory.
messageSender
No
Option to provide a custom WebServiceMessageSender. For example to perform authentication or
use alternative transports
messageFactory
No
Option to provide a custom WebServiceMessageFactory. For example when you want Apache
Axiom to handle web service messages instead of SAAJ
transformerFactory
No
Option to override default TransformerFactory. The provided transformer factory must be of type
javax.xml.transform.TransformerFactory
endpointMapping
Only when
mapping-type is
rootqname,
soapaction, uri
or xpathresult
Reference to org.apache.camel.component.spring.ws.bean.CamelEndpointMapping in the
Registry/ApplicationContext. Only one bean is required in the registry to serve all Camel/Spring-WS
endpoints. This bean is auto-discovered by the MessageDispatcher and used to map requests to
Camel endpoints based on characteristics specified on the endpoint (like root QName, SOAP action,
etc)
Message headers
Name
Type
Description
CamelSpringWebserviceEndpointUri
String
URI of the web service your accessing as a client, overrides address part of the
endpoint URI
CamelSpringWebserviceSoapAction
String
Header to specify the SOAP action of the message, overrides soapAction option if
present
CamelSpringWebserviceAddressingAction
URI
Use this header to specify the WS-Addressing action of the message, overrides
wsAddressingAction option if present
ACCESSING WEB SERVICES
To call a web service at http://foo.com/bar simply define a route:
from("direct:example").to("spring-ws:http://foo.com/bar")
And sent a message:
template.requestBody("direct:example", "test
message");
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Remember if it's a SOAP service you're calling you don't have to include
SOAP tags. Spring-WS will perform the XML-to-SOAP marshaling.
Sending SOAP and WS-Addressing action headers
When a remote web service requires a SOAP action or use of the WSAddressing standard you define your route as:
from("direct:example")
.to("spring-ws:http://foo.com/
bar?soapAction=http://foo.com&wsAddressingAction=http://bar.com")
Optionally you can override the endpoint options with header values:
template.requestBodyAndHeader("direct:example",
"test message",
SpringWebserviceConstants.SPRING_WS_SOAP_ACTION, "http://baz.com");
Using a custom MessageSender and MessageFactory
A custom message sender or factory in the registry can be referenced like
this:
from("direct:example")
.to("spring-ws:http://foo.com/
bar?messageFactory=#messageFactory&messageSender=#messageSender")
Spring configuration:
EXPOSING WEB SERVICES
In order to expose a web service using this component you first need to setup a MessageDispatcher to look for endpoint mappings in a Spring XML file. If
you plan on running inside a servlet container you probably want to use a
MessageDispatcherServlet configured in web.xml.
By default the MessageDispatcherServlet will look for a Spring XML
named /WEB-INF/spring-ws-servlet.xml. To use Camel with Spring-WS the
only mandatory bean in that XML file is CamelEndpointMapping. This bean
allows the MessageDispatcher to dispatch web service requests to your
routes.
web.xml
spring-wsorg.springframework.ws.transport.http.MessageDispatcherServlet1spring-ws/*
spring-ws-servlet.xml
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More information on setting up Spring-WS can be found in Writing ContractFirst Web Services. Basically paragraph 3.6 "Implementing the Endpoint" is
handled by this component (specifically paragraph 3.6.2 "Routing the
Message to the Endpoint" is where CamelEndpointMapping comes in). Also
don't forget to check out the Spring Web Services Example included in the
Camel distribution.
Endpoint mapping in routes
With the XML configuration in-place you can now use Camel's DSL to define
what web service requests are handled by your endpoint:
The following route will receive all web service requests that have a root
element named "GetFoo" within the http://example.com/ namespace.
from("spring-ws:rootqname:{http://example.com/
}GetFoo?endpointMapping=#endpointMapping")
.convertBodyTo(String.class).to(mock:example)
The following route will receive web service requests containing the
http://example.com/GetFoo SOAP action.
from("spring-ws:soapaction:http://example.com/
GetFoo?endpointMapping=#endpointMapping")
.convertBodyTo(String.class).to(mock:example)
The following route will receive all requests sent to http://example.com/
foobar.
from("spring-ws:uri:http://example.com/foobar?endpointMapping=#endpointMapping")
.convertBodyTo(String.class).to(mock:example)
The route below will receive requests that contain the element
abc anywhere inside the message (and the default
namespace).
from("spring-ws:xpathresult:abc?expression=//foobar&endpointMapping=#endpointMapping")
.convertBodyTo(String.class).to(mock:example)
Alternative configuration, using existing endpoint mappings
For every endpoint with mapping-type beanname one bean of type
CamelEndpointDispatcher with a corresponding name is required in the
Registry/ApplicationContext. This bean acts as a bridge between the Camel
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endpoint and an existing endpoint mapping like
PayloadRootQNameEndpointMapping.
An example of a route using beanname:
FutureEndpointDispatcherQuoteEndpointDispatcher
POJO (UN)MARSHALLING
Camel's pluggable data formats offer support for pojo/xml marshalling using
libraries such as JAXB, XStream, JibX, Castor and XMLBeans. You can use
these data formats in your route to sent and receive pojo's, to and from web
services.
When accessing web services you can marshal the request and unmarshal
the response message:
JaxbDataFormat jaxb = new JaxbDataFormat(false);
jaxb.setContextPath("com.example.model");
from("direct:example").marshal(jaxb).to("spring-ws:http://foo.com/
bar").unmarshal(jaxb);
Similarly when providing web services, you can unmarshal XML requests to
POJO's and marshal the response message back to XML:
from("spring-ws:rootqname:{http://example.com/
}GetFoo?endpointMapping=#endpointMapping").unmarshal(jaxb)
.to("mock:example").marshal(jaxb);
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The use of the beanname mapping-type is primarily meant for
(legacy) situations where you're already using Spring-WS and have
endpoint mappings defined in a Spring XML file. The beanname
mapping-type allows you to wire your Camel route into an existing
endpoint mapping. When you're starting from scratch it's
recommended to define your endpoint mappings as Camel URI's (as
illustrated above with endpointMapping) since it requires less
configuration and is more expressive. Alternatively you could use
vanilla Spring-WS with the help of annotations.
See Also
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•
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•
Configuring Camel
Component
Endpoint
Getting Started
STREAM COMPONENT
The stream: component provides access to the System.in, System.out and
System.err streams as well as allowing streaming of file and URL.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-streamx.x.x
URI format
stream:in[?options]
stream:out[?options]
stream:err[?options]
stream:header[?options]
In addition, the file and url endpoint URIs are supported in Camel 2.0:
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stream:file?fileName=/foo/bar.txt
stream:url[?options]
If the stream:header URI is specified, the stream header is used to find the
stream to write to. This option is available only for stream producers (that is,
it cannot appear in from()).
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Default
Value
Description
delay
0
Initial delay in milliseconds before consuming or producing the stream.
encoding
JVM Default
As of 1.4, you can configure the encoding (is a charset name) to use text-based streams (for example,
message body is a String object). If not provided, Camel uses the JVM default Charset.
promptMessage
null
Camel 2.0: Message prompt to use when reading from stream:in; for example, you could set this to
Enter a command:
promptDelay
0
Camel 2.0: Optional delay in milliseconds before showing the message prompt.
initialPromptDelay
2000
Camel 2.0: Initial delay in milliseconds before showing the message prompt. This delay occurs only
once. Can be used during system startup to avoid message prompts being written while other logging
is done to the system out.
fileName
null
Camel 2.0: When using the stream:file URI format, this option specifies the filename to stream to/
from.
scanStream
false
Camel 2.0: To be used for continuously reading a stream such as the unix tail command.
Camel 2.4 to Camel 2.6: will retry opening the file if it is overwritten, somewhat like tail --retry
retry
false
Camel 2.7: will retry opening the file if it's overwritten, somewhat like tail --retry
scanStreamDelay
0
Camel 2.0: Delay in milliseconds between read attempts when using scanStream.
groupLines
0
Camel 2.5: To group X number of lines in the consumer. For example to group 10 lines and therefore
only spit out an Exchange with 10 lines, instead of 1 Exchange per line.
Message content
The stream: component supports either String or byte[] for writing to
streams. Just add either String or byte[] content to the message.in.body.
The special stream:header URI is used for custom output streams. Just add a
java.io.OutputStream object to message.in.header in the key header.
See samples for an example.
Samples
In the following sample we route messages from the direct:in endpoint to
the System.out stream:
@Test
public void testStringContent() throws Exception {
template.sendBody("direct:in", "Hello Text World\n");
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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}
@Test
public void testBinaryContent() {
template.sendBody("direct:in", "Hello Bytes World\n".getBytes());
}
protected RouteBuilder createRouteBuilder() {
return new RouteBuilder() {
public void configure() {
from("direct:in").to("stream:out");
}
};
}
The following sample demonstrates how the header type can be used to
determine which stream to use. In the sample we use our own output stream,
MyOutputStream.
private OutputStream mystream = new MyOutputStream();
private StringBuffer sb = new StringBuffer();
@Test
public void testStringContent() {
template.sendBody("direct:in", "Hello");
// StreamProducer appends \n in text mode
assertEquals("Hello\n", sb.toString());
}
@Test
public void testBinaryContent() {
template.sendBody("direct:in", "Hello".getBytes());
// StreamProducer is in binary mode so no \n is appended
assertEquals("Hello", sb.toString());
}
protected RouteBuilder createRouteBuilder() {
return new RouteBuilder() {
public void configure() {
from("direct:in").setHeader("stream", constant(mystream)).
to("stream:header");
}
};
}
private class MyOutputStream extends OutputStream {
public void write(int b) throws IOException {
sb.append((char)b);
}
}
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The following sample demonstrates how to continuously read a file stream
(analogous to the UNIX tail command):
from("stream:file?fileName=/server/logs/
server.log&scanStream=true&scanStreamDelay=1000").to("bean:logService?method=parseLogLine");
One gotcha with scanStream (pre Camel 2.7) or scanStream + retry is the file
will be re-opened and scanned with each iteration of scanStreamDelay. Until
NIO2 is available we cannot reliably detect when a file is deleted/recreated.
See Also
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Configuring Camel
Component
Endpoint
Getting Started
STRING TEMPLATE
The string-template: component allows you to process a message using a
String Template. This can be ideal when using Templating to generate
responses for requests.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-stringtemplatex.x.x
URI format
string-template:templateName[?options]
Where templateName is the classpath-local URI of the template to invoke;
or the complete URL of the remote template.
You can append query options to the URI in the following format,
?option=value&option=value&...
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Options
Option
Default
Description
contentCache
false
New option in Camel 1.4. Cache for the resource content when its loaded.
Headers
Camel will store a reference to the resource in the message header with key,
org.apache.camel.stringtemplate.resource. The Resource is an
org.springframework.core.io.Resource object.
Hot reloading
The string template resource is by default hot-reloadable for both file and
classpath resources (expanded jar). If you set contentCache=true, Camel
loads the resource only once and hot-reloading is not possible. This scenario
can be used in production when the resource never changes.
StringTemplate Attributes
Camel will provide exchange information as attributes (just a
java.util.Map) to the string template. The Exchange is transfered as:
key
value
exchange
The Exchange itself.
headers
The headers of the In message.
camelContext
The Camel Context.
request
The In message.
in
The In message.
body
The In message body.
out
The Out message (only for InOut message exchange pattern).
response
The Out message (only for InOut message exchange pattern).
Samples
For example you could use a string template as follows in order to formulate
a response to a message:
from("activemq:My.Queue").
to("string-template:com/acme/MyResponse.tm");
The Email Sample
In this sample we want to use a string template to send an order
confirmation email. The email template is laid out in StringTemplate as:
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Dear $headers.lastName$, $headers.firstName$
Thanks for the order of $headers.item$.
Regards Camel Riders Bookstore
$body$
And the java code is as follows:
private Exchange createLetter() {
Exchange exchange = context.getEndpoint("direct:a").createExchange();
Message msg = exchange.getIn();
msg.setHeader("firstName", "Claus");
msg.setHeader("lastName", "Ibsen");
msg.setHeader("item", "Camel in Action");
msg.setBody("PS: Next beer is on me, James");
return exchange;
}
@Test
public void testVelocityLetter() throws Exception {
MockEndpoint mock = getMockEndpoint("mock:result");
mock.expectedMessageCount(1);
mock.expectedBodiesReceived("Dear Ibsen, Claus! Thanks for the order of Camel in
Action. Regards Camel Riders Bookstore PS: Next beer is on me, James");
template.send("direct:a", createLetter());
mock.assertIsSatisfied();
}
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
public void configure() throws Exception {
from("direct:a").to("string-template:org/apache/camel/component/
stringtemplate/letter.tm").to("mock:result");
}
};
}
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
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SQL COMPONENT
The sql: component allows you to work with databases using JDBC queries.
The difference between this component and JDBC component is that in case
of SQL the query is a property of the endpoint and it uses message payload
as parameters passed to the query.
This component uses spring-jdbc behind the scenes for the actual SQL
handling.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-sqlx.x.x
The SQL component also supports:
▪ a JDBC based repository for the Idempotent Consumer EIP pattern.
See further below.
▪ a JDBC based repository for the Aggregator EIP pattern. See further
below.
URI format
The SQL component uses the following endpoint URI notation:
sql:select * from table where id=# order by name[?options]
Notice that the standard ? symbol that denotes the parameters to an SQL
query is substituted with the # symbol, because the ? symbol is used to
specify options for the endpoint. The ? symbol replacement can be
configured on endpoint basis.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
925
Option
Type
Default
Description
dataSourceRef
String
null
Camel 1.5.1/2.0: Reference to a
DataSource to look up in the
registry.
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
The SQL component can only be used to define producer endpoints.
In other words, you cannot define an SQL endpoint in a from()
statement.
This component can be used as a Transactional Client.
placeholder
String
template.
#
Camel 2.4: Specifies a character
that will be replaced to ? in SQL
query. Notice, that it is simple
String.replaceAll() operation
and no SQL parsing is involved
(quoted strings will also change)
null
Sets additional options on the
Spring JdbcTemplate that is used
behind the scenes to execute the
queries. For instance,
template.maxRows=10. For detailed
documentation, see the
JdbcTemplate javadoc
documentation.
Treatment of the message body
The SQL component tries to convert the message body to an object of
java.util.Iterator type and then uses this iterator to fill the query
parameters (where each query parameter is represented by a # symbol (or
configured placeholder) in the endpoint URI). If the message body is not an
array or collection, the conversion results in an iterator that iterates over
only one object, which is the body itself.
For example, if the message body is an instance of java.util.List, the
first item in the list is substituted into the first occurrence of # in the SQL
query, the second item in the list is substituted into the second occurrence of
#, and so on.
Result of the query
For select operations, the result is an instance of List> type, as returned by the JdbcTemplate.queryForList() method. For
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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update operations, the result is the number of updated rows, returned as an
Integer.
Header values
When performing update operations, the SQL Component stores the update
count in the following message headers:
Header
Description
SqlProducer.UPDATE_COUNT
Camel 1.x: The number of rows updated for
update operations, returned as an Integer
object.
CamelSqlUpdateCount
Camel 2.0: The number of rows updated for
update operations, returned as an Integer
object.
CamelSqlRowCount
Camel 2.0: The number of rows returned for
select operations, returned as an Integer
object.
CamelSqlQuery
Camel 2.8: Query to execute. This query
takes precedence over the query specified
in the endpoint URI. Note that query
parameters in the header are represented
by a ? instead of a # symbol
Configuration in Camel 1.5.0 or lower
The SQL component must be configured before it can be used. In Spring, you
can configure it as follows:
Configuration in Camel 1.5.1 or higher
You can now set a reference to a DataSource in the URI directly:
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sql:select * from table where id=# order by name?dataSourceRef=myDS
Sample
In the sample below we execute a query and retrieve the result as a List of
rows, where each row is a Map instead containing each binding value.
template.sendBody("direct:simple", "XXX");
mock.assertIsSatisfied();
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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// the result is a List
List received = assertIsInstanceOf(List.class,
mock.getReceivedExchanges().get(0).getIn().getBody());
// and each row in the list is a Map
Map row = assertIsInstanceOf(Map.class, received.get(0));
// and we should be able the get the project from the map that should be Linux
assertEquals("Linux", row.get("PROJECT"));
We could configure the DataSource in Spring XML as follows:
Using the JDBC based idempotent repository
Available as of Camel 2.7: In this section we will use the JDBC based
idempotent repository.
First we have to create the database table which will be used by the
idempotent repository. For Camel 2.7, we use the follwing schema:
CREATE TABLE CAMEL_MESSAGEPROCESSED (
processorName VARCHAR(255),
messageId VARCHAR(100)
)
In Camel 2.8, we added the createdAt column:
CREATE TABLE CAMEL_MESSAGEPROCESSED (
processorName VARCHAR(255),
messageId VARCHAR(100),
createdAt TIMESTAMP
)
We recommend to have a unique constraint on the columns processorName
and messageId. Because the syntax for this constraint differs for database to
database, we do not show it here.
Second we need to setup a javax.sql.DataSource in the spring XML file:
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And finally we can create our JDBC idempotent repository in the spring XML
file as well:
messageId
Using the JDBC based aggregation repository
Available as of Camel 2.6
JdbcAggregationRepository is an AggregationRepository which on the fly
persists the aggregated messages. This ensures that you will not loose
messages, as the default aggregator will use an in memory only
AggregationRepository.
The JdbcAggregationRepository allows together with Camel to provide
persistent support for the Aggregator.
It has the following options:
Option
Type
Description
dataSource
DataSource
Mandatory: The javax.sql.DataSourc
database.
repositoryName
String
Mandatory: The name of the repository
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Using JdbcAggregationRepository in Camel 2.6
In Camel 2.6, the JdbcAggregationRepository is provided in the
camel-jdbc-aggregator component. From Camel 2.7 onwards, the
JdbcAggregationRepository is provided in the camel-sql
component.
transactionManager
TransactionManager
Mandatory: The
org.springframework.transaction.Pl
to mange transactions for the database.
must be able to support databases.
lobHandler
LobHandler
A org.springframework.jdbc.support
Lob types in the database. Use this optio
LobHandler, for example when using Ora
returnOldExchange
boolean
Whether the get operation should return
any existed. By default this option is fal
need the old exchange when aggregatin
useRecovery
boolean
Whether or not recovery is enabled. This
When enabled the Camel Aggregator au
aggregated exchange and have them re
recoveryInterval
long
If recovery is enabled then a background
to scan for failed exchanges to recover a
interval is 5000 millis.
maximumRedeliveries
int
Allows you to limit the maximum numbe
recovered exchange. If enabled then the
the dead letter channel if all redelivery a
this option is disabled. If this option is us
option must also be provided.
deadLetterUri
String
An endpoint uri for a Dead Letter Chann
recovered Exchanges will be moved. If t
maximumRedeliveries option must also
What is preserved when persisting
JdbcAggregationRepository will only preserve any Serializable
compatible data types. If a data type is not such a type its dropped and a
WARN is logged. And it only persists the Message body and the Message
headers. The Exchange properties are not persisted.
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Recovery
The JdbcAggregationRepository will by default recover any failed
Exchange. It does this by having a background tasks that scans for failed
Exchanges in the persistent store. You can use the checkInterval option to
set how often this task runs. The recovery works as transactional which
ensures that Camel will try to recover and redeliver the failed Exchange. Any
Exchange which was found to be recovered will be restored from the
persistent store and resubmitted and send out again.
The following headers is set when an Exchange is being recovered/
redelivered:
Header
Type
Description
Exchange.REDELIVERED
Boolean
Is set to true to indicate the
Exchange is being
redelivered.
Exchange.REDELIVERY_COUNTER
Integer
The redelivery attempt,
starting from 1.
Only when an Exchange has been successfully processed it will be marked as
complete which happens when the confirm method is invoked on the
AggregationRepository. This means if the same Exchange fails again it will
be kept retried until it success.
You can use option maximumRedeliveries to limit the maximum number
of redelivery attempts for a given recovered Exchange. You must also set the
deadLetterUri option so Camel knows where to send the Exchange when
the maximumRedeliveries was hit.
You can see some examples in the unit tests of camel-sql, for example this
test.
Database
To be operational, each aggregator uses two table: the aggregation and
completed one. By convention the completed has the same name as the
aggregation one suffixed with "_COMPLETED". The name must be configured
in the Spring bean with the RepositoryName property. In the following
example aggregation will be used.
The table structure definition of both table are identical: in both case a
String value is used as key (id) whereas a Blob contains the exchange
serialized in byte array.
However one difference should be remembered: the id field does not have
the same content depending on the table.
In the aggregation table id holds the correlation Id used by the component to
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aggregate the messages. In the completed table, id holds the id of the
exchange stored in corresponding the blob field.
Here is the SQL query used to create the tables, just replace
"aggregation" with your aggregator repository name.
CREATE TABLE aggregation (
id varchar(255) NOT NULL,
exchange blob NOT NULL,
constraint aggregation_pk PRIMARY KEY (id)
);
CREATE TABLE aggregation_completed (
id varchar(255) NOT NULL,
exchange blob NOT NULL,
constraint aggregation_completed_pk PRIMARY KEY (id)
);
Codec (Serialization)
Since they can contain any type of payload, Exchanges are not serializable
by design. It is converted into a byte array to be stored in a database BLOB
field. All those conversions are handled by the JdbcCodec class. One detail of
the code requires your attention: the
ClassLoadingAwareObjectInputStream.
The ClassLoadingAwareObjectInputStream has been reused from the
Apache ActiveMQ project. It wraps an ObjectInputStream and use it with the
ContextClassLoader rather than the currentThread one. The benefit is to
be able to load classes exposed by other bundles. This allows the exchange
body and headers to have custom types object references.
Transaction
A Spring PlatformTransactionManager is required to orchestrate
transaction.
Service (Start/Stop)
The start method verify the connection of the database and the presence of
the required tables. If anything is wrong it will fail during starting.
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Aggregator configuration
Depending on the targeted environment, the aggregator might need some
configuration. As you already know, each aggregator should have its own
repository (with the corresponding pair of table created in the database) and
a data source. If the default lobHandler is not adapted to your database
system, it can be injected with the lobHandler property.
Here is the declaration for Oracle:
See Also
•
•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
JDBC
TEST COMPONENT
Testing of distributed and asynchronous processing is notoriously difficult.
The Mock, Test and DataSet endpoints work great with the Camel Testing
Framework to simplify your unit and integration testing using Enterprise
Integration Patterns and Camel's large range of Components together with
the powerful Bean Integration.
The test component extends the Mock component to support pulling
messages from another endpoint on startup to set the expected message
bodies on the underlying Mock endpoint. That is, you use the test endpoint in
a route and messages arriving on it will be implicitly compared to some
expected messages extracted from some other location.
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So you can use, for example, an expected set of message bodies as files.
This will then set up a properly configured Mock endpoint, which is only valid
if the received messages match the number of expected messages and their
message payloads are equal.
Maven users will need to add the following dependency to their pom.xml
for this component when using Camel 2.8 or older:
org.apache.camelcamel-springx.x.x
From Camel 2.9 onwards the Test component is provided directly in the
camel-core.
URI format
test:expectedMessagesEndpointUri
Where expectedMessagesEndpointUri refers to some other Component
URI that the expected message bodies are pulled from before starting the
test.
Example
For example, you could write a test case as follows:
from("seda:someEndpoint").
to("test:file://data/expectedOutput?noop=true");
If your test then invokes the MockEndpoint.assertIsSatisfied(camelContext)
method, your test case will perform the necessary assertions.
To see how you can set other expectations on the test endpoint, see the
Mock component.
See Also
•
•
•
•
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Component
Endpoint
Getting Started
CH AP T E R 11 - C OM P ON E N T A P P E N DIX
• Spring Testing
TIMER COMPONENT
The timer: component is used to generate message exchanges when a timer
fires You can only consume events from this endpoint.
URI format
timer:name[?options]
Where name is the name of the Timer object, which is created and shared
across endpoints. So if you use the same name for all your timer endpoints,
only one Timer object and thread will be used.
You can append query options to the URI in the following format,
?option=value&option=value&...
Note: The IN body of the generated exchange is null. So
exchange.getIn().getBody() returns null.
Options
Name
Default
Value
Description
time
null
A java.util.Date the first event should be generated. If using the URI, the pattern expected is: yyyy-MM-dd
HH:mm:ss or yyyy-MM-dd'T'HH:mm:ss.
pattern
null
Allows you to specify a custom Date pattern to use for setting the time option using URI syntax.
period
1000
If greater than 0, generate periodic events every period milliseconds.
delay
0
The number of milliseconds to wait before the first event is generated. Should not be used in conjunction with
the time option.
fixedRate
false
Events take place at approximately regular intervals, separated by the specified period.
daemon
true
Specifies whether or not the thread associated with the timer endpoint runs as a daemon.
repeatCount
0
Camel 2.8: Specifies a maximum limit of number of fires. So if you set it to 1, the timer will only fire once. If
you set it to 5, it will only fire five times. A value of zero or negative means fire forever.
Exchange Properties
When the timer is fired, it adds the following information as properties to the
Exchange:
Name
Type
Description
Exchange.TIMER_NAME
String
The value of the name option.
Exchange.TIMER_TIME
Date
The value of the time option.
Exchange.TIMER_PERIOD
long
The value of the period option.
Exchange.TIMER_FIRED_TIME
Date
The time when the consumer fired.
Exchange.TIMER_COUNTER
Long
Camel 2.8: The current fire counter. Starts from 1.
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Advanced Scheduler
See also the Quartz component that supports much more advanced
scheduling.
Specify time in human friendly format
In Camel 2.3 onwards you can specify the time in human friendly
syntax.
Message Headers
When the timer is fired, it adds the following information as headers to the IN
message
Name
Type
Description
Exchange.TIMER_FIRED_TIME
java.util.Date
The time when the consumer fired
Sample
To set up a route that generates an event every 60 seconds:
from("timer://foo?fixedRate=true&period=60000").to("bean:myBean?method=someMethodName");
The above route will generate an event and then invoke the someMethodName
method on the bean called myBean in the Registry such as JNDI or Spring.
And the route in Spring DSL:
Firing only once
Available as of Camel 2.8
You may want to fire a message in a Camel route only once, such as when
starting the route. To do that you use the repeatCount option as shown:
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Instead of 60000 you can use period=60s which is more friendly to
read.
See Also
•
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
Quartz
VALIDATION COMPONENT
The Validation component performs XML validation of the message body
using the JAXP Validation API and based on any of the supported XML schema
languages, which defaults to XML Schema
Note that the Jing component also supports the following useful schema
languages:
• RelaxNG Compact Syntax
• RelaxNG XML Syntax
The MSV component also supports RelaxNG XML Syntax.
URI format
validator:someLocalOrRemoteResource
Where someLocalOrRemoteResource is some URL to a local resource on
the classpath or a full URL to a remote resource or resource on the file
system which contains the XSD to validate against. For example:
• msv:org/foo/bar.xsd
• msv:file:../foo/bar.xsd
• msv:http://acme.com/cheese.xsd
• validator:com/mypackage/myschema.xsd
C H A P TE R 1 1 - C O M P O NE N T A PPE NDIX
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Maven users will need to add the following dependency to their pom.xml for
this component when using Camel 2.8 or older:
org.apache.camelcamel-springx.x.x
From Camel 2.9 onwards the Validation component is provided directly in the
camel-core.
Options
Option
Default
Description
useDom
false
Camel 2.0: Whether DOMSource/DOMResult or SaxSource/SaxResult should be used by the validator.
useSharedSchema
true
Camel 2.3: Whether the Schema instance should be shared or not. This option is introduced to work around
a JDK 1.6.x bug. Xerces should not have this issue.
Example
The following example shows how to configure a route from endpoint
direct:start which then goes to one of two endpoints, either mock:valid or
mock:invalid based on whether or not the XML matches the given schema
(which is supplied on the classpath).
org.apache.camel.ValidationException
See Also
• Configuring Camel
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• Component
• Endpoint
• Getting Started
VELOCITY
The velocity: component allows you to process a message using an Apache
Velocity template. This can be ideal when using Templating to generate
responses for requests.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-velocityx.x.x
URI format
velocity:templateName[?options]
Where templateName is the classpath-local URI of the template to invoke;
or the complete URL of the remote template (eg: file://folder/myfile.vm).
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Option
Default
Description
loaderCache
true
Velocity based file loader cache.
New option in Camel 1.4: Cache for the resource content when it is loaded. By default, it's false in Camel
1.x. By default, it's true in Camel 2.x.
contentCache
encoding
null
New option in Camel 1.6: Character encoding of the resource content.
propertiesFile
null
New option in Camel 2.1: The URI of the properties file which is used for VelocityEngine initialization.
Message Headers
The velocity component sets a couple headers on the message (you can't set
these yourself and from Camel 2.1 velocity component will not set these
headers which will cause some side effect on the dynamic template support):
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Header
Description
org.apache.camel.velocity.resource
Camel 1.x: The resource as an org.springframework.core.io.Resource object.
org.apache.camel.velocity.resourceUri
Camel 1.x: The templateName as a String object.
CamelVelocityResource
Camel 2.0: The resource as an org.springframework.core.io.Resource object.
CamelVelocityResourceUri
Camel 2.0: The templateName as a String object.
In Camel 1.4 headers set during the Velocity evaluation are returned to the
message and added as headers. Then its kinda possible to return values from
Velocity to the Message.
For example, to set the header value of fruit in the Velocity template
.tm:
$in.setHeader('fruit', 'Apple')
The fruit header is now accessible from the message.out.headers.
Velocity Context
Camel will provide exchange information in the Velocity context (just a Map).
The Exchange is transfered as:
key
value
exchange
The Exchange itself.
exchange.properties
The Exchange properties.
headers
The headers of the In message.
camelContext
The Camel Context intance.
request
The In message.
in
The In message.
body
The In message body.
out
The Out message (only for InOut message exchange pattern).
response
The Out message (only for InOut message exchange pattern).
Hot reloading
The Velocity template resource is, by default, hot reloadable for both file and
classpath resources (expanded jar). If you set contentCache=true, Camel
will only load the resource once, and thus hot reloading is not possible. This
scenario can be used in production, when the resource never changes.
Dynamic templates
Available as of Camel 2.1
Camel provides two headers by which you can define a different resource
location for a template or the template content itself. If any of these headers
is set then Camel uses this over the endpoint configured resource. This
allows you to provide a dynamic template at runtime.
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Header
Type
Description
CamelVelocityResourceUri
String
Camel 2.1: A URI for the template resource to use instead of the endpoint configured.
CamelVelocityTemplate
String
Camel 2.1: The template to use instead of the endpoint configured.
Samples
For example you could use something like
from("activemq:My.Queue").
to("velocity:com/acme/MyResponse.vm");
To use a Velocity template to formulate a response to a message for InOut
message exchanges (where there is a JMSReplyTo header).
If you want to use InOnly and consume the message and send it to
another destination, you could use the following route:
from("activemq:My.Queue").
to("velocity:com/acme/MyResponse.vm").
to("activemq:Another.Queue");
And to use the content cache, e.g. for use in production, where the .vm
template never changes:
from("activemq:My.Queue").
to("velocity:com/acme/MyResponse.vm?contentCache=true").
to("activemq:Another.Queue");
And a file based resource:
from("activemq:My.Queue").
to("velocity:file://myfolder/MyResponse.vm?contentCache=true").
to("activemq:Another.Queue");
In Camel 2.1 it's possible to specify what template the component should
use dynamically via a header, so for example:
from("direct:in").
setHeader("CamelVelocityResourceUri").constant("path/to/my/template.vm").
to("velocity:dummy");
In Camel 2.1 it's possible to specify a template directly as a header the
component should use dynamically via a header, so for example:
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from("direct:in").
setHeader("CamelVelocityTemplate").constant("Hi this is a velocity template that
can do templating ${body}").
to("velocity:dummy");
The Email Sample
In this sample we want to use Velocity templating for an order confirmation
email. The email template is laid out in Velocity as:
Dear ${headers.lastName}, ${headers.firstName}
Thanks for the order of ${headers.item}.
Regards Camel Riders Bookstore
${body}
And the java code:
private Exchange createLetter() {
Exchange exchange = context.getEndpoint("direct:a").createExchange();
Message msg = exchange.getIn();
msg.setHeader("firstName", "Claus");
msg.setHeader("lastName", "Ibsen");
msg.setHeader("item", "Camel in Action");
msg.setBody("PS: Next beer is on me, James");
return exchange;
}
@Test
public void testVelocityLetter() throws Exception {
MockEndpoint mock = getMockEndpoint("mock:result");
mock.expectedMessageCount(1);
mock.expectedBodiesReceived("Dear Ibsen, Claus\n\nThanks for the order of Camel
in Action.\n\nRegards Camel Riders Bookstore\nPS: Next beer is on me, James");
template.send("direct:a", createLetter());
mock.assertIsSatisfied();
}
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
public void configure() throws Exception {
from("direct:a").to("velocity:org/apache/camel/component/velocity/
letter.vm").to("mock:result");
}
};
}
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See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
VM COMPONENT
The vm: component provides asynchronous SEDA behavior so that messages
are exchanged on a BlockingQueue and consumers are invoked in a separate
thread pool to the producer.
This component differs from the SEDA component in that VM supports
communication across CamelContext instances, so you can use this
mechanism to communicate across web applications, provided that the
camel-core.jar is on the system/boot classpath.
This component is an extension to the SEDA component.
URI format
vm:someName[?options]
Where someName can be any string to uniquely identify the endpoint within
the JVM (or at least within the classloader which loaded the camel-core.jar)
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
See the SEDA component for options and other important usage as the same
rules applies for this VM component.
Samples
In the route below we send the exchange to the VM queue that is working
across CamelContext instances:
from("direct:in").bean(MyOrderBean.class).to("vm:order.email");
And then in another Camel context such as deployed as in another .war
application:
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Camel 1.x to 2.3 - Same URI must be used for both producer
and consumer
An exactly identical VM endpoint URI must be used for both the
producer endpoint and the consumer endpoint. Otherwise Camel
will create a second VM endpoint, even thought the someName
portion of the URI is identical. For example:
from("direct:foo").to("vm:bar?concurrentConsumers=5");
from("vm:bar?concurrentConsumers=5").to("file://output");
Notice that we have to use the full URI including options in both the
producer and consumer.
In Camel 2.4 this has been fixed so its the queue name that must match,
eg in this example we are using bar as the queue name.
from("vm:order.email").bean(MyOrderEmailSender.class);
See Also
•
•
•
•
▪
Configuring Camel
Component
Endpoint
Getting Started
SEDA
XMPP COMPONENT
The xmpp: component implements an XMPP (Jabber) transport.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-xmppx.x.x
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URI format
xmpp://[login@]hostname[:port][/participant][?Options]
The component supports both room based and private person-person
conversations.
The component supports both producer and consumer (you can get
messages from XMPP or send messages to XMPP). Consumer mode supports
rooms starting from camel-1.5.0.
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
Name
Description
room
If this option is specified, the component will connect to MUC (Multi User Chat). Usually, the domain name for MUC is different
from the login domain. For example, if you are superman@jabber.org and want to join the krypton room, then the room URL
is krypton@conference.jabber.org. Note the conference part.
Starting from camel-1.5.0, it is not a requirement to provide the full room JID. If the room parameter does not contain the @
symbol, the domain part will be discovered and added by Camel
user
User name (without server name). If not specified, anonymous login will be attempted.
password
Password.
resource
XMPP resource. The default is Camel.
createAccount
If true, an attempt to create an account will be made. Default is false.
participant
JID (Jabber ID) of person to receive messages. room parameter has precedence over participant.
nickname
Use nickname when joining room. If room is specified and nickname is not, user will be used for the nickname.
serviceName
Camel 1.6/2.0 The name of the service you are connecting to. For Google Talk, this would be gmail.com.
Headers and setting Subject or Language
Camel sets the message IN headers as properties on the XMPP message. You
can configure a HeaderFilterStategy if you need custom filtering of
headers.
In Camel 1.6.2/2.0 the Subject and Language of the XMPP message are
also set if they are provided as IN headers.
Examples
User superman to join room krypton at jabber server with password,
secret:
xmpp://superman@jabber.org/?room=krypton@conference.jabber.org&password=secret
User superman to send messages to joker:
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xmpp://superman@jabber.org/joker@jabber.org?password=secret
Routing example in Java:
from("timer://kickoff?period=10000").
setBody(constant("I will win!\n Your Superman.")).
to("xmpp://superman@jabber.org/joker@jabber.org?password=secret");
Consumer configuration, which writes all messages from joker into the
queue, evil.talk.
from("xmpp://superman@jabber.org/joker@jabber.org?password=secret").
to("activemq:evil.talk");
Consumer configuration, which listens to room messages (supported from
camel-1.5.0):
from("xmpp://superman@jabber.org/
?password=secret&room=krypton@conference.jabber.org").
to("activemq:krypton.talk");
Room in short notation (no domain part; for camel-1.5.0+):
from("xmpp://superman@jabber.org/?password=secret&room=krypton").
to("activemq:krypton.talk");
When connecting to the Google Chat service, you'll need to specify the
serviceName as well as your credentials (as of Camel 1.6/2.0):
// send a message from fromuser@gmail.com to touser@gmail.com
from("direct:start").
to("xmpp://talk.google.com:5222/
touser@gmail.com?serviceName=gmail.com&user=fromuser&password=secret").
to("mock:result");
See Also
•
•
•
•
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Getting Started
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XQUERY
The xquery: component allows you to process a message using an XQuery
template. This can be ideal when using Templating to generate respopnses
for requests.
Maven users will need to add the following dependency to their pom.xml
for this component:
org.apache.camelcamel-saxonx.x.x
URI format
xquery:templateName
Where templateName is the classpath-local URI of the template to invoke;
or the complete URL of the remote template.
For example you could use something like this:
from("activemq:My.Queue").
to("xquery:com/acme/mytransform.xquery");
To use an XQuery template to formulate a response to a message for InOut
message exchanges (where there is a JMSReplyTo header).
If you want to use InOnly, consume the message, and send it to another
destination, you could use the following route:
from("activemq:My.Queue").
to("xquery:com/acme/mytransform.xquery").
to("activemq:Another.Queue");
See Also
•
•
•
•
Configuring Camel
Component
Endpoint
Getting Started
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XSLT
The xslt: component allows you to process a message using an XSLT
template. This can be ideal when using Templating to generate respopnses
for requests.
URI format
xslt:templateName[?options]
Where templateName is the classpath-local URI of the template to invoke;
or the complete URL of the remote template. Refer to the Spring
Documentation for more detail of the URI syntax
You can append query options to the URI in the following format,
?option=value&option=value&...
Here are some example URIs
URI
Description
xslt:com/acme/mytransform.xsl
refers to the file com/acme/mytransform.xsl on the classpath
xslt:file:///foo/bar.xsl
refers to the file /foo/bar.xsl
xslt:http://acme.com/cheese/foo.xsl
refers to the remote http resource
Maven users will need to add the following dependency to their pom.xml for
this component when using Camel 2.8 or older:
org.apache.camelcamel-springx.x.x
From Camel 2.9 onwards the XSLT component is provided directly in the
camel-core.
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Options
Name
Default
Value
Description
converter
null
Option to override default XmlConverter. Will lookup for the converter in the Registry. The
provided converted must be of type org.apache.camel.converter.jaxp.XmlConverter.
transformerFactory
null
Camel 1.6 Option to override default TransformerFactory. Will lookup for the transformerFactory
in the Registry. The provided transformer factory must be of type
javax.xml.transform.TransformerFactory.
transformerFactoryClass
null
Camel 1.6 Option to override default TransformerFactory. Will create a TransformerFactoryClass
instance and set it to the converter.
uriResolver
null
Camel 2.3: Allows you to use a custom javax.xml.transformation.URIResolver. Camel will by
default use its own implementation org.apache.camel.builder.xml.XsltUriResolver which is
capable of loading from classpath.
resultHandlerFactory
null
Camel 2.3: Allows you to use a custom
org.apache.camel.builder.xml.ResultHandlerFactory which is capable of using custom
org.apache.camel.builder.xml.ResultHandler types.
failOnNullBody
true
Camel 2.3: Whether or not to throw an exception if the input body is null.
deleteOutputFile
false
Camel 2.6: If you have output=file then this option dictates whether or not the output file
should be deleted when the Exchange is done processing. For example suppose the output file is
a temporary file, then it can be a good idea to delete it after use.
output
string
Camel 2.3: Option to specify which output type to use. Possible values are: string, bytes,
DOM, file. The first three options are all in memory based, where as file is streamed directly to
a java.io.File. For file you must specify the filename in the IN header with the key
Exchange.XSLT_FILE_NAME which is also CamelXsltFileName. Also any paths leading to the
filename must be created beforehand, otherwise an exception is thrown at runtime.
contentCache
true
Camel 2.6: Cache for the resource content (the stylesheet file) when it is loaded. If set to false
Camel will reload the stylesheet file on each message processing. This is good for development.
allowStAX
false
Camel 2.8.3/2.9: Whether to allow using StAX as the javax.xml.transform.Source.
Using XSLT endpoints
For example you could use something like
from("activemq:My.Queue").
to("xslt:com/acme/mytransform.xsl");
To use an XSLT template to formulate a response for a message for InOut
message exchanges (where there is a JMSReplyTo header).
If you want to use InOnly and consume the message and send it to
another destination you could use the following route:
from("activemq:My.Queue").
to("xslt:com/acme/mytransform.xsl").
to("activemq:Another.Queue");
Getting Parameters into the XSLT to work with
By default, all headers are added as parameters which are available in the
XSLT.
To do this you will need to declare the parameter so it is then useable.
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And the XSLT just needs to declare it at the top level for it to be available:
Spring XML versions
To use the above examples in Spring XML you would use something like
There is a test case along with its Spring XML if you want a concrete
example.
Using xsl:include
Camel 1.6.2/2.2 or older
If you use xsl:include in your XSL files then in Camel 2.2 or older it uses the
default javax.xml.transform.URIResolver which means it can only lookup
files from file system, and its does that relative from the JVM starting folder.
For example this include:
Will lookup the staff_tempkalte.xsl file from the starting folder where the
application was started.
Camel 1.6.3/2.3 or newer
Now Camel provides its own implementation of URIResolver which allows
Camel to load included files from the classpath and more intelligent than
before.
For example this include:
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Will now be located relative from the starting endpoint, which for example
could be:
.to("xslt:org/apache/camel/component/xslt/staff_include_relative.xsl")
Which means Camel will locate the file in the classpath as org/apache/
camel/component/xslt/staff_template.xsl.
This allows you to use xsl include and have xsl files located in the same
folder such as we do in the example org/apache/camel/component/xslt.
You can use the following two prefixes classpath: or file: to instruct
Camel to look either in classpath or file system. If you omit the prefix then
Camel uses the prefix from the endpoint configuration. If that neither has
one, then classpath is assumed.
You can also refer back in the paths such as
Which then will resolve the xsl file under org/apache/camel/component.
Notes on using XSTL and Java Versions
Here are some observations from Sameer, a Camel user, which he kindly
shared with us:
In case anybody faces issues with the XSLT endpoint please review
these points.
I was trying to use an xslt endpoint for a simple transformation
from one xml to another using a simple xsl. The output xml kept
appearing (after the xslt processor in the route) with outermost xml
tag with no content within.
No explanations show up in the DEBUG logs. On the TRACE logs
however I did find some error/warning indicating that the
XMLConverter bean could no be initialized.
After a few hours of cranking my mind, I had to do the following
to get it to work (thanks to some posts on the users forum that gave
some clue):
1. Use the transformerFactory option in the route ("xslt:mytransformer.xsl?transformerFactory=tFactory") with the
tFactory bean having bean defined in the spring context for
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class="org.apache.xalan.xsltc.trax.TransformerFactoryImpl".
2. Added the Xalan jar into my maven pom.
My guess is that the default xml parsing mechanism supplied
within the JDK (I am using 1.6.0_03) does not work right in this
context and does not throw up any error either. When I switched to
Xalan this way it works. This is not a Camel issue, but might need a
mention on the xslt component page.
Another note, jdk 1.6.0_03 ships with JAXB 2.0 while Camel needs
2.1. One workaround is to add the 2.1 jar to the jre/lib/endorsed
directory for the jvm or as specified by the container.
Hope this post saves newbie Camel riders some time.
See Also
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Configuring Camel
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