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<h1>JMS Queue Example</h1>
<p>This example shows you how to send and receive a message to a JMS Queue using ActiveMQ.</p>
<p>Queues are a standard part of JMS, please consult the JMS 1.1 specification for full details.</p>
<p>A Queue is used to send messages point to point, from a producer to a consumer. The queue guarantees message ordering between these 2 points.</p>
<h2>Example step-by-step</h2>
<p><i>To run the example, simply type <code>mvn verify -Pexample</code> from this directory</i></p>
<ol>
<li>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 <code>client-jndi.properties</code> file in the directory <code>../common/config</code></li>
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<code>InitialContext initialContext = getContext();</code>
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<li>We look-up the JMS queue object from JNDI</li>
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<code>Queue queue = (Queue) initialContext.lookup("/queue/exampleQueue");</code>
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<li>We look-up the JMS connection factory object from JNDI</li>
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<code>ConnectionFactory cf = (ConnectionFactory) initialContext.lookup("/ConnectionFactory");</code>
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<li>We create a JMS connection</li>
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<code>connection = cf.createConnection();</code>
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<li>We create a JMS session. The session is created as non transacted and will auto acknowledge messages.</li>
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<code>Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);</code>
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<li>We create a JMS message producer on the session. This will be used to send the messages.</li>
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<code>MessageProducer messageProducer = session.createProducer(topic);</code>
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<li>We create a JMS text message that we are going to send.</li>
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<code>TextMessage message = session.createTextMessage("This is a text message");</code>
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<li>We send message to the queue</li>
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<code>messageProducer.send(message);</code>
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<li>We create a JMS Message Consumer to receive the message.</li>
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<code>MessageConsumer messageConsumer = session.createConsumer(queue);</code>
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<li>We start the connection. In order for delivery to occur on any consumers or subscribers on a connection, the connection must be started</li>
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<code>connection.start();</code>
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<li>The message arrives at the consumer. In this case we use a timeout of 5000 milliseconds but we could use a blocking 'receive()'</li>
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<code>TextMessage messageReceived = (TextMessage) messageConsumer.receive(5000);</code>
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<li>And finally, <b>always</b> remember to close your JMS connections and resources after use, in a <code>finally</code> block. Closing a JMS connection will automatically close all of its sessions, consumers, producer and browser objects</li>
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<code>finally
{
if (initialContext != null)
{
initialContext.close();
}
if (connection != null)
{
connection.close();
}
}</code>
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