[Building Sakai] distributed state replication in sakai 2.6

[John Bush]

If we need to do distributed state replication in sakai 2.6, what is  
the suggested way?  Is there an agreed upon way?  I know a  
messageservice exists in contrib, or hide under ehcache, or  
terracotta.  Is it just pick your own poison?  Seems like unicon has  
done the most work in this area that I'm aware of anyway.  Is this  
something the product council should make a recommendation on?

The reason I'm asking is we've uncovered a rather nasty bug in webdav  
that is caused by the mac client in a cluster.  It brings down the  
server.  Its due to resource contention around locking.  I think its  
probably caused by how we are doing load balancing,  its not clear in  
our setup quite yet how to force webdav to be sticky, we are still  
looking into that.  If we pursue a state replication solution to  
replicate the locking state around the cluster, we'd like this work to  
make it into core, and would like some guidance on the appropriate way  
to do this for general adoption.

We are still researching this issue, expect a JIRA with more detail  
later today.

John