Apache Camel + JMS (ActiveMQ) Hello World Example

Overview

Previous tutorial we had implemented Apache Camel Example to use File Component and seen what are Routes and Components. In this tutorial we will making use of Apache Camel JMS Component. We will be reading from one JMS Queue and sending the message to another jms queue. Also we will be making use of ActiveMQ queues.

Technology Stack

We will be making use of-

Java 1.8
Apache Camel 3.0.0-M2
Maven
ActiveMQ 5.15.9

Implementation

ActiveMQ Installation and Startup

Go to ActiveMq Downloads Page and select the ActiveMQ downloads depending on your operating system.
Go to the location where you have unzipped the downloaded ActiveMQ installable and start ActiveMQ as follows-
Go to localhost:8161
Select Manage ActiveMQ Broker and you will be prompted for credentials. Enter the username and password as admin.
Select Queues. Currently we will see there are no Queues.

Apache Camel JMS implementation

The maven project we will be creating is as follows-
Apache Camel Maven Project

The pom.xml will be as follows-


<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.codeusingjava</groupId>
	<artifactId>apache-camel-jms</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<dependencies>
		<dependency>
			<groupId>org.apache.camel</groupId>
			<artifactId>camel-core</artifactId>
			<version>3.0.0-M2</version>
		</dependency>
		<dependency>
			<groupId>org.apache.camel</groupId>
			<artifactId>camel-jms</artifactId>
			<version>3.0.0-M2</version>
		</dependency>
		<dependency>
			<groupId>org.apache.activemq</groupId>
			<artifactId>activemq-camel</artifactId>
			<version>5.15.9</version>
		</dependency>
		<dependency>
			<groupId>org.apache.activemq</groupId>
			<artifactId>activemq-broker</artifactId>
			<version>5.15.9</version>
		</dependency>
	</dependencies>
</project>

For this example we make use of Java DSL for writing Routes. A Route consists of Message Channel for using which applications communicate using Messages. The end points of these message channels either consume of produce messages.

Apache Camel Endpoints

What are Components?

Component act as an endpoint factory using which we can interact with external systems. Camel provides a large number of components using which we can interact with externals systems.
We have to transfer a data from one JMS Queue to another JMS Queue so we make use of the JMS Component.
Apache Camel Components

In Apache Camel for creating a route we need to extend RouteBuilder class and override configure method. Then in configure method we define our route. So our route using Java DSL will be as follows-


package com.codeusingjava.route;

import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.builder.RouteBuilder;

public class JMSRouteBuilder extends RouteBuilder {

	@Override
	public void configure() throws Exception {
		from("jmsComponent:queue:codeusingjava-inputqueue").process(new Processor() {
			public void process(Exchange exchange) throws Exception {
				System.out.println(exchange.getIn().getBody());
			}
		}).to("jmsComponent:queue:codeusingjava-outputqueue");
	}

}

What is CamelContext?

We cannot run our Camel Application only using the route. We also need the camel context which acts as a runtime system that runs and manages the routes. It is responsible for all managing all aspects of a route.
Apache Camel Maven Project

We create and configure Apache Camel Component using the following steps -

1. Create CamelContext.
2. Add routes to the CamelContext.
3. Start the CamelContext. So that the Routes get executed.
4. Stop the Camel Context.

We define the CamelContext in the CamelMain class as follows-


package com.codeusingjava;

import javax.jms.ConnectionFactory;

import org.apache.activemq.spring.ActiveMQConnectionFactory;
import org.apache.camel.CamelContext;
import org.apache.camel.component.jms.JmsComponent;
import org.apache.camel.impl.DefaultCamelContext;
import com.codeusingjava.route.JMSRouteBuilder;

public class CamelMain {

	public static void main(String[] args) {
		CamelContext ctx = new DefaultCamelContext();

		ConnectionFactory connectionFactory = new ActiveMQConnectionFactory();
		ctx.addComponent("jmsComponent", JmsComponent.jmsComponentAutoAcknowledge(connectionFactory));

		JMSRouteBuilder jmsRouteBuilder = new JMSRouteBuilder();

		try {
			ctx.addRoutes(jmsRouteBuilder);
			ctx.start();
			Thread.sleep(5 * 60 * 1000);
			ctx.stop();
		} catch (Exception e) {
			e.printStackTrace();
		}

	}
}

Run the Application. We will see that one queue created now.
Apache Camel Route1

If we send a message in codeusingjava-inputqueue it gets transferred to the codeusingjava-outputqueue .
Apache Camel Route2

Downloads-

Apache Camel JMS Example