Additional SOA Patterns –Supporting Composition Controllers - Applied SOA Patterns on the Oracle Platform - page 567

<cluster>
<server-name>epnserver1</server-name>
<multicast-address><your_server_ip></multicast-address>
<groups>cargoHandlingDeploymentGroup,
ActiveActiveGroupBean_group1 </groups>
<enabled>true</enabled>
</cluster>
As you can see from the preceding examples, we are moving in two-by-two form-
ation here: four hosts (servers) in two notification groups and two servers in each
of these groups as primary and secondary. The event input has two selector condi-
tions in the message selector section. With more than one host in the notification
group, GroupBean makes sure that only the primary node gets the event notific-
ation message. If the primary node is down, the next in line will be promoted as
primary: