I understand that Mobicents PS is not supported now but I want to understand about the scalability of MSPS.
I understand from the source code that MSPS uses JBoss Cache instead of the database to store presence information. I understand the concept of cache but no idea of JBoss cache.
It seems that the storage is limited by the amount of memory available in the machine and whenever a new node(physical machine) is to be added the cache has to be replicated into that machine.
Is this correct behavior or my understanding is totally wrong.
The database is used and JBoss Cache is aimed to be used for replication of some of the volatile data to support failover. Your mention about cache replication is correct but the memory limits concerns can be mitigated by using buddy replication instead of full cluster replication. If you move to Cassandra and use in memory data grid such as infinispan or hazelcast, will be better nowadays.
The traditional presence has moved on from sharing all status from all contacts. Its valid to mention for example the issue on GitHub about Presence API, that is currently in development (https://github.com/Mobicents/RestComm/issues/380).
Would you like to contribute either to Presence Server or RestComm Presence in general?