activemq-artemis/examples/jms/send-acknowledgements
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readme.html

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    <title>ActiveMQ Asynchronous Send Acknowledgements Example</title>
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     <h1>Asynchronous Send Acknowledgements Example</h1>

     <p>Asynchronous Send Acknowledgements are an advanced feature of ActiveMQ which allow you to
     receive acknowledgements that messages were successfully received at the server in a separate thread to the sending thread<p/>
     <p>In this example we create a normal JMS session, then set a SendAcknowledgementHandler on the JMS 
     session's underlying core session. We send many messages to the server without blocking and asynchronously
     receive send acknowledgements via the SendAcknowledgementHandler.

     <p>For more information on Asynchronous Send Acknowledgements please see the user manual</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>
        <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>Define a SendAcknowledgementHandler which will receive asynchronous acknowledgements</li>
        <pre class="prettyprint">
           <code>
         class MySendAcknowledgementsHandler implements SendAcknowledgementHandler
         {
            int count = 0;
            
            public void sendAcknowledged(final Message message)
            {
               System.out.println("Received send acknowledgement for message " + count++);
            }            
         }           
           </code>
        </pre>

        <li>Create a JMS session</li>
        <pre class="prettyprint">
          <code>Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);</code>
       </pre>

        <li>Set the handler on the underlying core session</li>
        <pre class="prettyprint">
           <code>
         ClientSession coreSession = ((ActiveMQSession)session).getCoreSession();
         
         coreSession.setSendAcknowledgementHandler(new MySendAcknowledgementsHandler());
           
           </code>
        </pre>

        <li>Create a JMS Message Producer</li>
        <pre class="prettyprint">
           <code>
         MessageProducer producer = session.createProducer(queue);
         
         producer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);           
           </code>
        </pre>

        <li>Send 5000 messages, the handler will get called asynchronously some time later after the messages are sent.</li>
          <pre class="prettyprint">
           <code>
         final int numMessages = 5000;
         
         for (int i = 0; i < numMessages; i++)
         {
            javax.jms.Message jmsMessage = session.createMessage();
            
            producer.send(jmsMessage);
            
            System.out.println("Sent message " + i);
         }           
           </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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