This is intended as an umbrella ticket collecting work related to user session clustering as described in more detail here: http://confluence.sakaiproject.org/confluence/x/iwACAQ

At this writing, we're looking at clustering Sakai sessions by replicating session attributes (and possibly other fields) via a distributed cache, probably implemented by ehcache.

Subtickets may be associated with any number of Jira components. I chose to associate this ticket with the "Tool (SVN module)," though, since that's where Sakai's SessionManager is currently factored, and it seemed worthwhile to pick at least one Jira component so as not to drop out of filters someone might construct to look for session-related issues in general. There is a "Clustering (SVN module)" component, that might _seem_ like a better choice, at least w/r/t its name, but as it currently stands that module is mainly concerned with maintaining a registry of Sakai instances associated with a cluster rather than replicating/sharing data (user-scoped or otherwise) within a cluster, which is what we're most interested in at the moment.