Factory for clusters used by Apache mod-JK
These Clusters are built dynamically, when a new server is discovered
as being part of a cluster of this type.
Logical Cluster: may be created by jonasAdmin, or declared in domain.xml
A default logical cluster is created for each domain, it holds all the
servers in the doamin.
Factory for clusters used by Tomact for Session Replication
These Clusters are built dynamically, when a new server is discovered
as being part of a cluster of this type.