<h1>Java EE MDB using a local transaction Example</h1>
<p>This example shows you how to send a message to an MDB and deliver it within a local transaction</p>
<p>The example will send deploy a simple MDB and demonstrate sending a message and the MDB consuming it, throwing an exception and the message being re delivered.</p>
<p>The example leverages the JBoss Arquillian framework to run a WildFly instance and deploy the MDB.</p>
<h2>Example step-by-step</h2>
<p><i>download WildFly 8.0.0.Final from <ahref="http://wildfly.org/downloads/">here</a> and install.</i></p>
<p><i>set the JBOSS_HOME property to point to the WildFly install directory</i></p>
<p><i>type <code>mvn verify</code> from the example directory to run</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>jndi.properties</code> file in the directory <code>config</code></li>
<li>We create a JMS text messages that we are going to send.</li>
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TextMessage message = session.createTextMessage("This is a text message");
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<li>We send messages to the queue</li>
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messageProducer.send(message);
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<li>The MDB receives the message<br/>
We know the message is a TextMessage so we cast to it.
</li>
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TextMessage tm = (TextMessage)message;
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<li>The MDB gets the text and prints it, we take a quick look at the transaction and throw an exception.
</li>
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System.out.println("message " + text + " received");
if (!textMessage.getJMSRedelivered())
{
//Step 11. On first delivery get the transaction, take a look, and throw an exception
Transaction tx = tm.getTransaction();
if (tx != null)
{
System.out.println("something is wrong, there should be no global transaction: " + tx);
}
else
{
System.out.println("there is no global transaction, although the message delivery is using a local transaction");
System.out.println("let's throw an exception and see what happens");
throw new RuntimeException("DOH!");
}
}
</pre>
<li>The MDB receives the message again and we print a message.
</li>
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System.out.println("The message was redelivered since the message delivery used a local transaction");
</pre>
<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>
