In this example
we will create a single java application which will send and receive messages
from RabbitMQ using spring amqp.
Design:
- Exchange type: Fanout exchange
- Input argument: String
- Queue argument: default arguments
- Configuration type: xml based configuration
- We can pass String or Message(org.springframework.amqp.core.Message) as input argument. We will see what are the advantages of using each type in the coming posts
- When we create a queue, it is created with few default values like durable as true, auto delete as false etc, we will try to understand what each value means and also configure other optional parameters like TTL, Dead letter exchange etc and understand the behavior
- We will also look how to configure using annotations in the comings tutorials
In this tutorial, we will create 2 queues (myQueue1 and myQueue2) and bind them to fanout exchange (myExchange) created. In our main class, we send the messages to the exchange and retrieve message both the queues which are bound to this exchange.
Prerequisites:
- RabbitMQ is installed locally
- Maven is configured
Step 1: Update the pom.xml with spring-amqp and spring-core dependencies
<dependency>
<groupId>org.springframework.amqp</groupId>
<artifactId>spring-rabbit</artifactId>
<version>1.4.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>3.2.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>3.2.2.RELEASE</version>
</dependency>
Step 2: Update the spring context xml with rabbit connection, exchange and queue details
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:rabbit="http://www.springframework.org/schema/rabbit"
xsi:schemaLocation="http://www.springframework.org/schema/rabbit
http://www.springframework.org/schema/rabbit/spring-rabbit-1.4.xsd
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> In the xml file, we declare connection factory, rabbit template, queues, bindings etc. Among these few attributes are optional depending on the design or development approach of your application. In order to understand more about each attribute please click here<rabbit:connection-factory id="connectionFactory" host="localhost" username="guest" password="guest" /> <rabbit:template id="rabbitTemplate" connection-factory="connectionFactory" exchange="myExchange" /> <rabbit:admin connection-factory="connectionFactory" /> <rabbit:queue name="myQueue1" /> <rabbit:queue name="myQueue2" /> <rabbit:fanout-exchange name="myExchange"> <rabbit:bindings> <rabbit:binding queue="myQueue1" /> <rabbit:binding queue="myQueue2" /> </rabbit:bindings> </rabbit:fanout-exchange>
Step 3: Create main class to send and receive messages using RabbitTemplate
AbstractApplicationContext context = new ClassPathXmlApplicationContext("rabbit-context.xml");
RabbitTemplate rabbitTemplate = context.getBean(RabbitTemplate.class);
rabbitTemplate.convertAndSend("Message");
String msg1 = (String) rabbitTemplate.receiveAndConvert("myQueue1");
System.out.println(msg1);
String msg2 = (String) rabbitTemplate.receiveAndConvert("myQueue2");
System.out.println(msg2);
When we run the above class, rabbitTemplate sends the message string to the exchange which is configured in the rabbit-context.xml and then receive the message from the one of the queues specified in the argument of the receive method.
In the next tutorial, we will look at how to add a listener class so that we process the messages automatically
