Http Session Failover

User interactions with WebSphere Portal Server are maintained through the use of a
HttpSession. This provides a way to preserve data across multiple pages or requests on an individual user basis. The failure or outage, either scheduled or unscheduled, of a WebSphere Portal Server cluster member will result in the termination of the user's HttpSession.

You can configure WebSphere Application server so that in case of failure the Users Http Session is available to the other cluster, this is called distributed session. WAS provides following two options to do this

  • Database session persistence, where sessions are stored in the database specified.

  • Memory-to-memory session replication, where sessions are stored in one or more specified WebSphere Application Server instances or profiles.

When a session contains attributes that implement HttpSessionActivationListener, notification occurs anytime the session is activated (that is, session is read to the memory cache) or passivated (that is, session leaves the memory cache). Passivation can occur because of a server shutdown or when the session memory cache is full and an older session is removed from the memory cache to make room for a newer session. It is not guaranteed that a session is passivated in one application server prior to activation in another application.

When you store an attribute in the PortletSession it actually gets stored in the HttpSession only the attribute name is stored in the namespaced format.

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