JMS Topic Example

This example shows you how to send and receive a message to a JMS Topic with ActiveMQ.

Topics are a standard part of JMS, please consult the JMS 1.1 specification for full details.

A Topic is used to send messages using the publish-subscribe model, from a producer to 1 or more consumers.

Example step-by-step

To run the example, simply type mvn verify -Pexample from this directory

1. First we need to get an initial context so we can look-up the JMS connection factory and destination objects from JNDI. This initial context will get it's properties from the client-jndi.properties file in the directory ../common/config

           InitialContext initialContext = getContext();
        

2. We look-up the JMS topic object from JNDI

           Topic topic = (Topic) initialContext.lookup("/topic/exampleTopic");
        

3. We look-up the JMS connection factory object from JNDI

           ConnectionFactory cf = (ConnectionFactory) initialContext.lookup("/ConnectionFactory");
        

4. We create a JMS connection

           connection = cf.createConnection();
        

5. We create a JMS session. The session is created as non transacted and will auto acknowledge messages.

           Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        

6. We create a JMS message producer on the session. This will be used to send the messages.

          MessageProducer messageProducer = session.createProducer(topic);
       

7. We create a JMS Message Consumer, messageConsumer1, to receive the message.

           MessageConsumer messageConsumer = session.createConsumer(topic);
         

8. We create a JMS Message Consumer, messageConsumer2, to also receive the message.

          MessageConsumer messageConsumer2 = session.createConsumer(topic);
        

9. We create a JMS text message that we are going to send.

           TextMessage message = session.createTextMessage("This is a text message");
        

10. We send message to the topic

           messageProducer.send(message);
        

11. We start the connection. In order for delivery to occur on any consumers or subscribers on a connection, the connection must be started

           connection.start();
        

12. The message arrives at the first consumer

           TextMessage messageReceived = (TextMessage) messageConsumer1.receive();
        

13. The message arrives at the second consumer

           messageReceived = (TextMessage) messageConsumer2.receive();
        

14. And finally, always remember to close your JMS connections and resources after use, in a finally block. Closing a JMS connection will automatically close all of its sessions, consumers, producer and browser objects

           finally
           {
              if (initialContext != null)
              {
                initialContext.close();
              }
              if (connection != null)
              {
                 connection.close();
              }
           }