Multi-group support in Shoal
Shoal now has support for a multi-group environment. This has special value in the Sailfin project.
Ericsson and Sun are working together to develop a Telecommunications Application Server under the name of Sailfin. One of the parts of Sailfin is a Java based load balancer called Converged Load Balancer (CLB). The CLB takes care of load balancing both HTTP and SIP based requests. It is a component of the Sailfin appserver instance. So any cluster instance can be configured as a load balancer. Such an instance can be part of a Front End LB Cluster performing load balancing of requests on a separate application server cluster tier or it can be part of a Self LoadBalancing Cluster wherein one or more instances of the application server cluster also perform the role of a load balancer while also serving requests.
This is where Shoal's multi-group support comes in.
The cluster instances rely on Shoal for getting the information on group dynamics. With this feature, an instance can now be a core member of a cluster that has been created for load balancing purposes and at the same time be a spectator in a cluster of instances that are serving the client requests. This is just one such use case.
I have written a test com.sun.enterprise.ee.cms.tests.multigroupjoin.MultiGroupJoinTest which displays that an instance can be part of 2 groups and send messages to and receive messages from both groups.
Please do let us know at the users alias about this feature and also about what you would like to see added in Shoal to serve your clustering and fault tolerance needs.
