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<h1>JMS Temporary Queue Example</h1>
<p>This example shows you how to use a TemporaryQueue with ActiveMQ. First a temporary queue is created to send and receive a message and then deleted.
Then another temporary queue is created and used after its connection is closed to illustrate its scope.</p>
<p>A TemporaryQueue is a JMS queue that exists only within the lifetime of its connection. It is often used in request-reply
type messaging where the reply is sent through a temporary destination. The temporary queue is often created as
a server resource, so after using, the user should call delete() method to release the resources.
Please consult the JMS 1.1 specification for full details.</p>
<h2>Example step-by-step</h2>
<p><i>To run the example, simply type <code>mvn verify</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 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 = getContext();</code>
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<li>We look-up JMS connection factory 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 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>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 Temporary Queue</li>
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<code>Queue tempQueue = session.createTemporaryQueue();</code>
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<li>We create a JMS message producer to the temporary queue. This will be used to send the messages.</li>
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<code>MessageProducer messageProducer = session.createProducer(tempQueue);</code>
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<li>We create a JMS text message 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 the message to the temporary queue</li>
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<code>messageProducer.send(message);</code>
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<li>We create a message consumer of the temporary queue</li>
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<code>MessageConsumer messageConsumer = session.createConsumer(tempQueue);</code>
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<li>We receive the message from the temporary queue</li>
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<code>message = (TextMessage) messageConsumer.receive(5000);</code>
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<li>We close the consumer and producer before destroying the temporary queue</li>
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<code>messageConsumer.close();</code>
<code>messageProducer.close();</code>
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<li>We delete the temporary queue</li>
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<code>tempQueue.delete();</code>
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<li>We create another temporary queue</li>
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<code>TemporaryQueue tempQueue2 = session.createTemporaryQueue();</code>
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<li>We close the connection</li>
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<code>connection.close();</code>
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<li>We create a new connection</li>
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<code>connection = cf.createConnection();</code>
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<li>We create a new session</li>
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<code>session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);</code>
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<li>We try to access the tempQueue2 outside its lifetime, this will cause exception thrown</li>
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<code>
try
{
messageConsumer = session.createConsumer(tempQueue2);
throw new Exception("Temporary queue cannot be accessed outside its lifecycle!");
}
catch (InvalidDestinationException e)
{
System.out.println("Exception got when trying to access a temp queue outside its scope: " + e);
}
</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>
</pre>
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