Limitations of In-Memory Replication

Chapter 8 Creating J2EE Applications for BEA WebLogic

Limitations of In-Memory Replication

By replicating the state of a stateful session EJB, clients are generally guaranteed to have the last committed state of the EJB, even if the primary WebLogic Server instance fails. However, in certain rare failover scenarios, the last committed state may not be available. This can happen when:

A client commits a transaction involving a stateful EJB, but the primary WebLogic Server fails before the EJB's state is replicated. In this scenario, the client's next method invocation will work against the previous committed state, if available.
A client creates an instance of a stateful session EJB and commits an initial transaction, but the primary WebLogic Server fails before the EJB's initial state can be replicated. In this scenario the client's next method invocation will fail to locate the bean instance, because the initial state could not be replicated. The client would need to recreate the EJB instance using the clustered EJBHome stub, and restart the transaction.
Both the primary and secondary servers fail. In this scenario the client would need to recreate the EJB instance and restart the transaction.