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<title>ActiveMQ Artemis JMS Load Balanced Static Clustered Queue Example</title>
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<h1>JMS Load Balanced Static Clustered One Way Queue Example</h1>
<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>
<p>This example demonstrates a JMS queue deployed on three different nodes. The three nodes are configured to form a one way cluster
from a <em>static</em> list of nodes. </p>
<p>A one way cluster is different from a symmetrical cluster in that each node is only connected to one another node in
a chain type fashion, so server 0 -> server 1 -> server 2</p>
<p>We then create a consumer on the queue on each node, and we create a producer on only one of the nodes.</p>
<p>We then send some messages via the producer, and we verify that <b>all</b> consumers receive the sent messages
in a round-robin fashion.</p>
<p>In other words, ActiveMQ Artemis <b>load balances</b> the sent messages across all consumers on the cluster</p>
<p>This example uses JNDI to lookup the JMS Queue and ConnectionFactory objects. If you prefer not to use
JNDI, these could be instantiated directly.</p>
<p>Here's the relevant snippet from the server configuration, which tells the server to form a one way cluster between the three nodes
and to load balance the messages between the nodes. Note that we have set <em>allow-direct-connections-only</em> to true,
this means that this server will only ever connect the address's specified in the list of connectors. ALso notice
that <em>max-hops</em> is 2, this is because server 0 is not directly connected to server 2, 2 hops in fact, so we
allow any updates from servers up to 2 hops away</p>
<pre class="prettyprint">
<code>
<cluster-connection name="my-cluster">
<connector-ref>netty-connector</connector-ref>
<retry-interval>500</retry-interval>
<use-duplicate-detection>true</use-duplicate-detection>
<message-load-balancing>STRICT</message-load-balancing>
<max-hops>2</max-hops>
<static-connectors allow-direct-connections-only="true">
<connector-ref>server1-connector</connector-ref>
</static-connectors>
</cluster-connection>
</code>
</pre>
<p>For more information on ActiveMQ Artemis load balancing, and clustering in general, please see the clustering
section of the user manual.</p>
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