Tasks Session data
WAS handles HTTP session persistence using two ways:
- Memory-to-memory replication to create a copy of the session data in one or more additional servers
- Store the session data in an external database.
External database persistence will survive node failures and appserver restarts, but introduces a new single point of failure that must be mitigated using an external hardware clustering or high availability solution. Memory-to-memory replication can reduce the impact of failure, but if a node fails, the data held on that node is lost.
Stateful session EJB availability is handled using memory-to-memory replication only. Using the EJB container properties, we can specify a replication domain for the EJB container and enable the stateful session bean failover using memory-to-memory replication. When enabled, all stateful session beans in the container are able to fail over to another instance of the bean and still maintain the session state.