118 lines
5.4 KiB
HTML
118 lines
5.4 KiB
HTML
<html>
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<title>ActiveMQ JMS Instantiate Connection Factory Example</title>
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<link rel="stylesheet" type="text/css" href="../common/prettify.css" />
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<body onload="prettyPrint()">
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<h1>JMS Instantiate Connection Factory Example</h1>
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<p>Usually, JMS Objects such as ConnectionFactories, Queue and Topic instances are looked up from JNDI
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before being used by the client code. This objects are called "administered objects" in JMS specification
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terminology.</p>
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<p>However, in some cases a JNDI server may not be available or desired. To come to the rescue ActiveMQ
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also supports the direct instantiation of these administered objects on the client side.</p>
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<p>This allows the full set of JMS functionality to be available without requiring a JNDI server!</p>
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<p>This example is very simple and based on the simple Queue example, however in this example we
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instantiate the JMS Queue and ConnectionFactory objects directly.</p>
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<p>A wide variety of methods are available for instantiating ConnectionFactory objects. In this example
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we use a simple method which just takes the server connection details so it knows where to make the
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connection to.</p>
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<p>Other methods are available so all the connection factory parameters can be specified
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including specifying UDP discovery so the client does not need hard-wired knowledge of where the servers
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are that it wishes to connect to, or for specifying live-backup pairs of servers for failover.</p>
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<p>For more information on instantiating ConnectionFactories directly please consult the user manual and
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javadoc.</p>
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<h2>Example step-by-step</h2>
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<p><i>To run the example, simply type <code>mvn verify</code> from this directory</i></p>
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<ol>
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<li>Instead of looking it up from JNDI we directly instantiate the JMS Queue object. We
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pass in the name of the JMS Queue in the constructor. The actual JMS Queue must already be deployed on
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the server.</li>
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<pre class="prettyprint">
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<code>
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Queue queue = new ActiveMQQueue("exampleQueue");</code>
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</pre>
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<li>Instantiate the TransportConfiguration object. The TransportConfiguration instance encapsulates
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the connection details of the server we're connecting to. In this case we're using Netty as a transport, and
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we're specifying to connect on port 5446.</li>
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<pre class="prettyprint">
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<code>
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Map<String, Object> connectionParams = new HashMap<String, Object>();
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connectionParams.put(PORT_PROP_NAME, 5446);
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TransportConfiguration transportConfiguration = new TransportConfiguration(NettyConnectorFactory.class.getName(),
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connectionParams);
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</code>
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</pre>
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<li>Directly instantiate the JMS ConnectionFactory object using that TransportConfiguration.</li>
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<pre class="prettyprint">
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<code>
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ConnectionFactory cf = ActiveMQJMSClient.createConnectionFactoryWithoutHA(transportConfiguration);
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</code>
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</pre>
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<li>We create a JMS connection</li>
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<pre class="prettyprint">
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<code>connection = cf.createConnection();</code>
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</pre>
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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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<pre class="prettyprint">
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<code>Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);</code>
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</pre>
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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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<pre class="prettyprint">
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<code>MessageProducer messageProducer = session.createProducer(topic);</code>
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</pre>
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<li>We create a JMS text message that we are going to send.</li>
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<pre class="prettyprint">
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<code>TextMessage message = session.createTextMessage("This is a text message");</code>
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</pre>
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<li>We send message to the queue</li>
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<pre class="prettyprint">
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<code>messageProducer.send(message);</code>
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</pre>
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<li>We create a JMS Message Consumer to receive the message.</li>
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<pre class="prettyprint">
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<code>MessageConsumer messageConsumer = session.createConsumer(queue);</code>
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</pre>
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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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<pre class="prettyprint">
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<code>connection.start();</code>
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</pre>
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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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<pre class="prettyprint">
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<code>TextMessage messageReceived = (TextMessage) messageConsumer.receive(5000);</code>
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</pre>
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<li>And finally, <b>always</b> remember to close your resources after use, in a <code>finally</code> block.</li>
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<pre class="prettyprint">
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<code>finally
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{
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if (connection != null)
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{
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connection.close();
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}
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}</code>
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</pre>
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</ol>
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</body>
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