activemq-artemis/examples/jms/scheduled-message
Martyn Taylor 3e34044d2b [maven-release-plugin] prepare for next development iteration 2015-05-11 21:50:41 +01:00
..
src/main fixed examples and some docs after Artemis renaming 2015-04-30 10:44:16 +01:00
pom.xml [maven-release-plugin] prepare for next development iteration 2015-05-11 21:50:41 +01:00
readme.html added examples to release profile 2015-03-08 13:34:02 +00:00

readme.html

<!--
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
-->

<html>
  <head>
    <title>ActiveMQ Scheduled Message Example</title>
    <link rel="stylesheet" type="text/css" href="../common/common.css" />
    <link rel="stylesheet" type="text/css" href="../common/prettify.css" />
    <script type="text/javascript" src="../common/prettify.js"></script>
  </head>
  <body onload="prettyPrint()">
     <h1>JMS Scheduled Message Example</h1>

     <p>This example shows you how to send a scheduled message to a JMS Queue using ActiveMQ.</p>
     <p>A Scheduled Message is a message that will be delivered at a time specified by the sender. To do this, 
     simply set a HDR_SCHEDULED_DELIVERY_TIME header property. The value of the property should be the time of 
     delivery in milliseconds. </p>
     
     <p>In this example, a message is created with the scheduled delivery time set to 5 seconds after the current time.</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 producer = session.createProducer(queue);</code>
       </pre>

        <li>We create a JMS text message that we are going to send.</li>
        <pre class="prettyprint">
           <code>TextMessage message = session.createTextMessage("This is a scheduled message message which will be delivered in 5 sec.");</code>
        </pre>

        <li>We schedule the delivery time to be 5 sec later.</li>
        <pre class="prettyprint">
           <code>
            long time = System.currentTimeMillis();
            time += 5000;
            message.setLongProperty(MessageImpl.HDR_SCHEDULED_DELIVERY_TIME.toString(), time);
           </code>
        </pre>

        <li>We send message to the queue</li>
        <pre class="prettyprint">
           <code>messageProducer.send(message);</code>
        </pre>

        <li>We create a JMS Message Consumer to receive the message.</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>We use a blocking receive() to consume the message and see when the message arrives.</li>
        <pre class="prettyprint">
           <code>TextMessage messageReceived = (TextMessage) messageConsumer.receive();</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>

     </ol>
     
     <h2>More information</h2>
     
     <ul>
         <li>User Manual's <a href="../../../docs/user-manual/en/html_single/index.html#scheduled-messages">Scheduled Messages chapter</a></li>
     </ul>
     
  </body>
</html>