activemq-artemis/examples/jms/browser
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readme.html

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    <title>ActiveMQ JMS QueueBrowser Example</title>
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     <h1>JMS QueueBrowser Example</h1>

     <p>This example shows you how to use a JMS <a href="http://java.sun.com/javaee/5/docs/api/javax/jms/QueueBrowser.html">QueueBrowser</a> with ActiveMQ.<br />
     Queues are a standard part of JMS, please consult the JMS 1.1 specification for full details.<br />
     A QueueBrowser is used to look at messages on the queue without removing them. 
     It can scan the entire content of a queue or only messages matching a message selector.</p>
     <p>
         The example will send 2 messages on a queue, use a QueueBrowser to browse 
         the queue (looking at the message without removing them) and finally consume the 2 messages
     </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>
        <pre class="prettyprint">
           <code>InitialContext initialContext = getContext();</code>
        </pre>

        <li>We look up the JMS queue object from JNDI</li>
        <pre class="prettyprint">
           <code>Queue queue = (Queue) initialContext.lookup("/queue/exampleQueue");</code>
        </pre>

        <li>We look up the JMS connection factory object from JNDI</li>
        <pre class="prettyprint">
           <code>ConnectionFactory cf = (ConnectionFactory) initialContext.lookup("/ConnectionFactory");</code>
        </pre>

        <li>We create a JMS connection</li>
        <pre class="prettyprint">
           <code>connection = cf.createConnection();</code>
        </pre>

        <li>We create a JMS session. The session is created as non transacted and will auto acknowledge messages.</li>
        <pre class="prettyprint">
           <code>Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);</code>
        </pre>

        <li>We create a JMS message producer on the session. This will be used to send the messages.</li>
        <pre class="prettyprint">
          <code>MessageProducer messageProducer = session.createProducer(topic);</code>
       </pre>

        <li>We create 2 JMS text messages that we are going to send.</li>
        <pre class="prettyprint">
           <code> TextMessage message_1 = session.createTextMessage("this is the 1st message");
            TextMessage message_2 = session.createTextMessage("this is the 2nd message");</code>
        </pre>

        <li>We send messages to the queue</li>
        <pre class="prettyprint">
           <code>messageProducer.send(message_1);
           messageProducer.send(message_2);</code>
        </pre>
        
        <li>We create a JMS QueueBrowser.<br />
            We have not specified a message selector so the browser will enumerate the entire content of the queue.
            </li>
        <pre class="prettyprint">
           <code>QueueBrowser browser = session.createBrowser(queue);</code>
        </pre>
            
        <li>We browse the queue and display all the messages' text
        </li>
        <pre class="prettyprint">
            <code>Enumeration messageEnum = browser.getEnumeration();
            while (messageEnum.hasMoreElements())
            {
               TextMessage message = (TextMessage)messageEnum.nextElement();
               System.out.println("Browsing: " + message.getText());
            }</code>
        </pre>
        
        <li>We close the browser once we have finished to use it</li>
        <pre class="prettyprint">
            <code>browser.close();</code>
        </pre>

        <p>The messages were browsed but they were not removed from the queue. We will now consume them.</p>
        
        <li>We create a JMS Message Consumer to receive the messages.</li>
          <pre class="prettyprint">
           <code>MessageConsumer messageConsumer = session.createConsumer(queue);</code>
        </pre>

        <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>
        <pre class="prettyprint">
           <code>connection.start();</code>
        </pre>

        <li>The 2 messages arrive at the consumer</li>
        <pre class="prettyprint">
           <code>TextMessage messageReceived = (TextMessage)messageConsumer.receive(5000);
           System.out.println("Received message: " + messageReceived.getText());
           messageReceived = (TextMessage)messageConsumer.receive(5000);
           System.out.println("Received message: " + messageReceived.getText());</code>
        </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>

        <pre class="prettyprint">
           <code>finally
           {
              if (initialContext != null)
              {
                initialContext.close();
              }
              if (connection != null)
              {
                 connection.close();
              }
           }</code>
        </pre>



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