This tutorial is a work in progress. Any additions, corrections or feedback very much appreciated. Please use the comment box if making a correction explaining the mistake.

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.

{warning}This tutorial is a work in progress.  Any additions, corrections or feedback very much appreciated.  Please use the comment box if making a correction explaining the mistake.{warning}

h1. 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|http://www.springramework.org] service.  The route works in a synchronous fashion returning a response to the client.

{toc}

h1. TODOs
* Embellish the tutorial with more detail, explaining at each stage what is happening.
* Link to specific sections of Camel documentation when referring to components.
* -Attach completed example project.-
* Explain in more detail what is happening when the JMS component is being defined in camel-server.xml
* Show how logging can be introduced to monitor exchange body contents.
* Detail how time-outs can be configured.
* Show how to catch lost messages.
* Show how to use a wiretap.
* Can we make this ActiveMQ embedded so that it does not require the reader to download and start it manually?

h1. Prerequisites

This tutorial uses ActiveMQ as the JMS broker. [Download|http://activemq.apache.org/download.html] and extract it, then start the broker using script in the bin directory.
It is assumed that the reader is familiar with Spring (including v2.5 features) and Maven.

h1. Create the Camel Project

{info}
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.
{info}

{code}
mvn archetype:create -DgroupId=org.example -DartifactId=CamelWithJmsAndSpring
{code}

h2. Update the POM with Dependencies

{code}.example -DartifactId=CamelWithJmsAndSpring

<dependencies>
  <dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.14</version>
  </dependency>
  <dependency>
    <groupId>org.apache.activemq</groupId>
    <artifactId>activemq-all</artifactId>
    <version>5.0.0</version>
  </dependency>
  <dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-core</artifactId>
    <version>1.3.0</version>
  </dependency>
  <dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-jms</artifactId>
    <version>1.3.0</version>
  </dependency>
  <dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-spring</artifactId>
    <version>1.3.0</version>
  </dependency>

  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit-dep</artifactId>
    <version>4.4</version>
    <scope>test</scope>
  </dependency>
</dependencies>
{code}

h1. Writing the Server

h2. Create the Spring Service

For this example the Spring service on the server will be a simple multiplier which trebles in the received value.  The classes should reside in the package {{

}
@Service(value="multiplier")
public class Treble implements Multiplier {

  /* (non-Javadoc)
   * @see org.example.server.Multiplier#multiply(int)
   */
  public int multiply(final int originalNumber) {
    return originalNumber * 3;
  }

}
{code}

}
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:camel="http://activemq.apache.org/camel/schema/spring"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
		http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
		http://www.springframework.org/schema/context
		http://schemas.leadx.com/spring/spring-context-2.5.xsd
		http://activemq.apache.org/camel/schema/spring
		http://activemq.apache.org/camel/schema/spring/camel-spring-1.3.0.xsd">
		
	<context:component-scan base-package="org.example.server" />

	<camel:camelContext id="camel">
		<camel:package>org.example.server</camel:package>
	</camel:camelContext>

	<bean id="jms" class="org.apache.camel.component.jms.JmsComponent">
		<property name="connectionFactory">
			<bean class="org.apache.activemq.ActiveMQConnectionFactory">
				<property name="brokerURL" value="tcp://localhost:61616" />
			</bean>
		</property>
	</bean>

</beans>
{code}

|

}
public class CamelServer {

  public static void main(final String[] args) {
    ApplicationContext context = new ClassPathXmlApplicationContext("camel-server.xml");
  }

}
{code}

The {{main}} method can then be executed to start the server.

h1. Creating the Client

We will initially create a client by directly using {{CamelTemplate}}.  We will later create a client which uses Spring remoting to hide the fact that messaging is being used.

{code:title=camel-client.xml|xml}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:camel="http://activemq.apache.org/camel/schema/spring"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
		http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
		http://activemq.apache.org/camel/schema/spring
		http://activemq.apache.org/camel/schema/spring/camel-spring-1.3-SNAPSHOT.xsd">

	<camel:camelContext id="camel" />
	<camel:template id="camelTemplate" />
	
	<bean id="jms" class="org.apache.camel.component.jms.JmsComponent">
		<property name="connectionFactory">
			<bean class="org.apache.activemq.ActiveMQConnectionFactory">
				<property name="brokerURL" value="tcp://localhost:61616" />
			</bean>
		</property>
	</bean>
</beans>
{code}

}
public class CamelClient {

  public static void main(final String[] args) {

    ApplicationContext context = new ClassPathXmlApplicationContext("camel-client.xml");
    CamelTemplate<JmsExchange> camelTemplate = (CamelTemplate) context.getBean("camelTemplate");

    int response = (Integer)camelTemplate.sendBody("jms:queue:numbers",
      ExchangePattern.InOut,
      22
    );

    Assert.assertEquals(66, response);
    System.out.println(response);

  }
}
{code}

The {{CamelTemplate}} 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.  We then assert that the response is three times the value of the original.

Before running the client be sure that both the ActiveMQ broker and the {{CamelServer}} are running.

h1. 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.

{code:title=

|xml}
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:camel="http://activemq.apache.org/camel/schema/spring"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
		http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
		http://activemq.apache.org/camel/schema/spring
		http://activemq.apache.org/camel/schema/spring/camel-spring-1.3-SNAPSHOT.xsd">

	<camel:camelContext id="camel" />
	
	<camel:proxy
		id="multiplier"
		serviceInterface="org.example.server.Multiplier"
		serviceUrl="jms:queue:numbers"
	/>
	
	<bean id="jms" class="org.apache.camel.component.jms.JmsComponent">
		<property name="connectionFactory">
			<bean class="org.apache.activemq.ActiveMQConnectionFactory">
				<property name="brokerURL" value="tcp://localhost:61616" />
			</bean>
		</property>
	</bean>
</beans>
{code}

Require an explanation here about the deployment options of Camel based projects

(e.g.

running

through

Maven,

creating

a

host

application,

deploying

into

ActiveMQ)

and

the

pros/cons

of

each.

 
{note}

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.

{code|title=pom.xml}
<build>
  <plugins>
    <plugin>
      <groupId>org.apache.camel</groupId>
      <artifactId>camel-maven-plugin</artifactId>
    </plugin>      
  </plugins>
</build>
{code}