WAS v8.5 > Reference > Administrator best practicesSession recovery support
For session recovery support, WebSphere Application Server provides distributed session support in the form of database sessions. We 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 website 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.
Related concepts:
Sessions
Distributed sessions
Related
Tasks: Managing HTTP sessions