With the session failover functionality, a J2EE server can inherit the information of the objects registered in the HttpSession object on another J2EE server.

Invoke a session that you can inherit and use between multiple J2EE servers as a global session. An HTTP session is lost if a failure occurs on the J2EE server, which handles that session. On the other hand, because a global session is managed by a process (a database or EADs server) other than the J2EE server, it is not lost even if a failure occurs on the J2EE server. As a result, if a failure occurs on one J2EE server, you can create an HTTP session on another J2EE server and inherit the global session information.

If you are using a global session, the information of the HttpSession object that is inherited on another J2EE server, is called the global session information.

For details on the scope of the HTTP session and global session, see the following figure.

Figure 5-2 Scope of HTTP session and global session

With the session failover functionality, because the global session information is inherited when a failure occurs on a J2EE server, you can continue operations in the state before the failure occurrence without reporting an error to the user.