62 lines
3.4 KiB
HTML
62 lines
3.4 KiB
HTML
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<html>
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<head>
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<title>ActiveMQ Artemis Message Redistribution Example</title>
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<link rel="stylesheet" type="text/css" href="../common/common.css" />
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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>Message Redistribution Example</h1>
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<pre>To run the example, simply type <b>mvn verify</b> from this directory, <br>or <b>mvn -PnoServer verify</b> if you want to start and create the server manually.</pre>
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<p>This example demonstrates message redistribution between queues with the same name deployed in different
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nodes of a cluster.</p>
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<p>As demontrated in the clustered queue example, if queues with the same name are deployed on different nodes of
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a cluster, ActiveMQ Artemis can be configured to load balance messages between the nodes on the server side.</p>
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<p>However, if the consumer(s) on a particular node are closed, then messages in the queue at that node can
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appear to be stranded, since they have no local consumers.</p>
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<p>If this is undesirable, ActiveMQ Artemis can be configured to <b>redistribute</b> messages from the node
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with no consumers, to nodes where there are consumers. If the consumers have JMS selectors set on them, then they
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will only be redistributed to nodes with consumers whose selectors match.</p>
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<p>By default, message redistribution is disabled, but can be enabled by specifying some AddressSettings configuration
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in either <code>activemq-queues.xml</code> or <code>broker.xml</code></p>
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<p>Setting <code>redistribution-delay</code> to <code>0</code> will cause redistribution to occur immediately
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once there are no more matching consumers on a particular queue instance. Setting it to a positive value > 0 specifies
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a delay in milliseconds before attempting to redistribute. The delay is useful in the case that another consumer is
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likely to be created on the queue, to avoid unnecessary redistribution.</p>
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<p>Here's the relevant snippet from the <code>activemq-queues.xml</code> configuration, which tells the server
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to use a redistribution delay of <code>0</code> on any jms queues, i.e. any queues whose name starts with
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<code>jms.</code></p>
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<pre class="prettyprint">
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<code>
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<address-setting match="jms.#">
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<redistribution-delay>0</redistribution-delay>
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</address-setting>
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</code>
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</pre>
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<p>For more information on ActiveMQ Artemis load balancing, and clustering in general, please see the clustering
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section of the user manual.</p>
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</body>
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</html>
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