Provide Support for Clustered Singleton MDBs

Provide Support for Clustered Singleton MDBs.

Provide annotation and configuration support to mark such MDB deployments Clustered Singleton MDBs.

When "Clustered Singleton MDBs" are deployed in a cluster; only one node (server) is active to consume messages serially. When the node fails; another the active node's "Clustered Singleton MDBs" starts consuming the messages.

To mark an MDB as clustered singleton, one can either use the clustered-singleton xml element, like this:
<jboss:ejb-jar xmlns:jboss="http://www.jboss.com/xml/ns/javaee"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:c="urn:clustering:1.1"
xmlns:d="urn:delivery-active:1.1"
xsi:schemaLocation="http://www.jboss.com/xml/ns/javaee http://www.jboss.org/j2ee/schema/jboss-ejb3-2_0.xsd http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/ejb-jar_3_1.xsd"
version="3.1"
impl-version="2.0">
<c:clustering>
<ejb-name>HelloWorldQueueMDB</ejb-name>
<c:clustered-singleton>true</c:clustered-singleton>
</c:clustering>
</jboss:ejb-jar>

Or one can use the @org.jboss.ejb3.annotation.ClusteredSingleton in your MDB class.

This feature requires no extra configuration at the server, apart from running the service in a cluster.