We will conclude this chapter by discussing the messaging subsystem.

The JMS provider used in WildFly is HornetQ. In order to share the message processing load, HornetQ servers can be grouped together in a cluster. Each active node in the cluster contains an active HornetQ server. HornetQ manages its own messages and handles its own connections. Behind the scenes, when a node forms a cluster connection to another node, a core bridge connection is created between them. Once the connection has been established, messages can flow between each of the nodes.

Clustering is automatically enabled in HornetQ if one or more cluster-connection elements are defined. The following example is taken from the default full-ha profile:

<subsystem xmlns="urn:jboss:domain:messaging:2.0">
    <hornetq-server>
        ...
        <cluster-connections>
             <cluster-connection name="my-cluster">
                 <address>jms</address&gt...