When you configure OpenSSO Enterprise for session failover, the user's authenticated session state is stored in the Berkeley Database in the event of a single hardware or software failure. In session failover deployments, you configure the OpenSSO Enterprise servers to communicate with Message Queue brokers which manage session state persistence in the Berkeley Database. This configuration enables the users session to fail over to a backup OpenSSO Enterprise server without losing any session state information. The user does not have to login again. The backup OpenSSO Enterprise server is determined among the available servers in the configuration list by an internal algorithm.
This type of deployment ensures the state availability even if one of the OpenSSO Enterprise servers is inaccessible due to scheduled maintenance, hardware failure, or software failure. However, the single load balancer can be a single point of failure. When this load balancer is inaccessible, no OpenSSO Enterprise services or session data are available to the Policy Agents.
The following figure illustrates the components in a basic OpenSSO Enterprise deployment using session failover.
The following figure illustrates the session handling part of the process flow. See Figure 17–2 for a detailed illustration of steps 1 through 13.