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<h1>JMS Auto Closable Example</h1>
<p>This example shows you how JMS resources, such as connections, sessions and consumers, in JMS 2 can be automatically closed on error.</p>
<p>In this instance we auto close a connection after a subsequent call to a JMS producer send fails</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 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 context but we do it inside the try-with-resources statement like so:</li>
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<code>
try
(
JMSContext jmsContext = cf.createContext()
)
</code>
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<li>Inside the following try block we first create the producer</li>
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<code>JMSProducer jmsProducer = jmsContext.createProducer();</code>
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<li>We then try to send a message. It is this call that throws an exception as the producer doesn't have the privileges
to send a message</li>
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<code>jmsProducer.send(queue, "this message will fail security!");</code>
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<li>We catch the exception from the send message and can do what we want, however the JMSContext will have been closed
prior to entering the catch block.</li>
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<code>System.out.println("expected exception from jmsProducer.send: " + e.getMessage());</code>
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<li>And finally, we close the Initial Context, note we no longer have to worry about clearing up the JMSContext.</li>
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<code>finally
{
if (initialContext != null)
{
initialContext.close();
}
}</code>
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