[jboss-dev-forums] [Design of Clustering on JBoss] - Re: Removing SFSB in HttpSessionListener

[bstansberry@jboss.com]

This touches on a general problem where there isn't a sufficiently developed notion of session 'ownership' in the cluster. The 'owner' would be the node responsible for managing the lifecycle of the session. In this case, the owner would send out the notifications, and shutting down would entail giving up ownership (so no notification.) Unless you are the last node in the cluster.

Similarly, only the owner would expire a session due to timeout, and would do it with a cluster-wide remove. Replace the current approach of every node doing a local-only remove.

What needs working out is the process of taking over ownership.  Simple enough if the session fails over.  Less so if not.  You can't reliably count on JGroups view changes to signal an existing owner has given up ownership, since if a cache is shared between webapps, undeploying a webapp != changing the cache view.  There would need to be a facility for signalling within the cluster when a node is handling a webapp.

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