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John A. Lewis
Unicon, Inc.
Introduction
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JSR-168 Portlet applications represent a special challenge when it comes to clustering within Tomcat (or any other servlet container, for that matter). In order to effectively cluster web applications, session data must be replicated or shared between the nodes in the cluster. Otherwise, the user experiences a complete loss of context during a node failover. While Tomcat has provided session replication for quite some time, it has not supported replication of session changes resulting from a cross-context call from one webapp to another. |
Portlets that are deployed as separate webapps from the portal webapp must be accessed by cross-context calls from the portal. This cross-context access creates a number of issues: servlet filters are not applied, session sharing between servlets and portlets is difficult, and session replication in Tomcat did not work.
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