Session clustering can be accomplished on Tomcat 4.1.* with Coherence
. Coherence includes a Servlet 2.3 Http Session Replication Module out of the box.
In our Coherence 2.3 release (currently in pre-release) a new module will be included to manage http sessions in all Servlet 2.2, 2.3 and 2.4 compliant containers. This new module will allow for more robust configuration of the caching strategy behind the session management including Near, Replicated, Distributed (Partitioned), etc.
: Cluster your Work. Work your Cluster.