For the single cache case, the user should specify SharedJBossCacheRegionFactory as their hibernate.cache.region.factory_class.

As part of its startup process, the region factory delegates responsibility for providing JBoss Cache instances to an implementation of the org.hibernate.cache.jbc2.CacheInstanceManager interface. The region factory separately requests a JBoss Cache instance for entities, one for collections, one for queries and one for timestamps. Whether the CacheInstanceManager provides the same underlying JBoss Cache instance for each request or provides multiple caches is an implementation detail of the CacheInstanceManager.

SharedJBossCacheRegionFactory creates an instance of SharedCacheInstanceManager as its CacheInstanceManager. SharedCacheInstanceManager uses the JBoss Cache configuration file specified by the user to create a single org.jboss.cache.Cache instance, and provides that same instance to the region factory when it requests the cache for entities, collections, queries and timestamps. SharedCacheInstanceManager also creates an org.jgroups.ChannelFactory and passes it to the Cache. The ChannelFactory provides the cache with the org.jgroups.Channel it uses for intra-cluster communication.

At this point, the region factory has a reference to a cache for entities, a reference to a cache for collections, one for queries and one for timestamps. In this particular case, each reference points to the same underlying Cache instance. When core Hibernate invokes the buildEntityRegion operation on the region factory, it instantiates an implementation of the EntityRegion interface that knows how to interface with JBoss Cache, passing it a reference to its entity cache. Same thing happens for collections, etc.

Core Hibernate invokes on the EntityRegion, which in turn invokes read and write operations on the underlying JBoss Cache. The cache uses its Channel to propagate changes to its peers in the cluster.

When the SessionFactory shuts down, it invokes stop() on the region factory, which in turn ensures that the JBoss Cache instance is stopped and destroyed (which in turn closes the JGroups channel).