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<title>ActiveMQ JMS Shared Consumer Example</title>
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<h1>JMS Shared Consumer Example</h1>
<p>This example shows you how can use shared consumers to share a subscription on a topic. In JMS 1.1 this was not allowed
and so caused a scalability issue. In JMS 2 this restriction has been lifted so you can share the load across different
threads and connections.</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 topic object from JNDI</li>
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<code>Topic topic = (Topic) initialContext.lookup("/topic/exampleTopic");</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</li>
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<code>jmsContext = cf.createContext();</code>
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<li>We create a JMS Producer.</li>
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<code>JMSProducer producer = jmsContext.createProducer();</code>
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<li>We create a shared consumer using the subscription name <literal>sc1</literal></li>
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<code>JMSConsumer jmsConsumer = jmsContext.createSharedConsumer(topic, "sc1");</code>
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<li>We then create a second JMS context for a second shared consumer</li>
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<code>jmsContext2 = cf.createContext();</code>
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<li>we then create the second shared consumer using the same subscription name</li>
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<code>JMSConsumer jmsConsumer2 = jmsContext2.createSharedConsumer(topic, "sc1");</code>
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<li>we then send 2 messages</li>
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<code>
producer.send(topic, "this is a String!");
producer.send(topic, "this is a second String!") ;</code>
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<li>we then receive the 2 messages using both shared consumers</li>
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<code>
String body = jmsConsumer.receiveBody(String.class, 5000);
body = jmsConsumer2.receiveBody(String.class, 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 (jmsContext != null)
{
jmsContext.close();
}
if (jmsContext2 != null)
{
jmsContext2.close();
}
}</code>
</pre>
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