For session recovery support, WebSphere Application Server provides distributed session support in the form of database sessions and memory-to-memory replication. You can use session recovery support when the user's session data must be maintained across a server restart or when the user's session data is too valuable to lose through an unexpected server failure.
All the attributes set in a session must implement java.io.Serializable
if the session requires external storage. In general, consider making all
objects held by a session serialized, even if immediate plans do not call
for session recovery support. If the Web site grows, and session recovery
support becomes necessary, the transition occurs transparently to the application
if the sessions only hold serialized objects. If not, a switch to session
recovery support requires coding changes to make the session contents serialized.