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