18.1. Stateless Session Bean in EJB 2.x

Clustering stateless session beans is most probably the easiest case: as no state is involved, calls can be load-balanced on any participating node (i.e. any node that has this specific bean deployed) of the cluster. To make a bean clustered, you need to modify its jboss.xml descriptor to contain a <clustered> tag.

<jboss>    
    <enterprise-beans>      
        <session>        
            <ejb-name>nextgen.StatelessSession</ejb-name>        
            <jndi-name>nextgen.StatelessSession</jndi-name>        
            <clustered>True</clustered>        
            <cluster-config>          
                <partition-name>DefaultPartition</partition-name>          
                <home-load-balance-policy>                 
                    org.jboss.ha.framework.interfaces.RoundRobin          
                </home-load-balance-policy>          
                <bean-load-balance-policy>  
                    org.jboss.ha.framework.interfaces.RoundRobin
                </bean-load-balance-policy>
            </cluster-config>
        </session>
    </enterprise-beans>
</jboss>

Note

The <clustered>True</clustered> element is really just an alias for the <configuration-name>Clustered Stateless SessionBean</configuration-name> element in the conf/standard-jboss.xml file.

In the bean configuration, only the <clustered> element is mandatory. It indicates that the bean needs to support clustering features. The <cluster-config> element is optional and the default values of its attributes are indicated in the sample configuration above. Below is a description of the attributes in the <cluster-config> element..

partition-name specifies the name of the cluster the bean participates in. The default value is DefaultPartition. The default partition name can also be set system-wide using the jboss.partition.name system property.
home-load-balance-policy indicates the class to be used by the home stub to balance calls made on the nodes of the cluster. By default, the proxy will load-balance calls in a RoundRobin fashion. You can also implement your own load-balance policy class or use the class FirstAvailable that persists to use the first node available that it meets until it fails.
bean-load-balance-policy Indicates the class to be used by the bean stub to balance calls made on the nodes of the cluster. Comments made for the home-load-balance-policy attribute also apply.