Clustered environments

One of the things that we failed to mention in our initial diagram of a single logout was how the logout is performed. Unfortunately, it is implemented by storing a mapping of the service ticket to HttpSession as an in-memory map. This means that a single logout will not work properly within a clustered environment:

Consider the following situation:

• The user logs in to Cluster Member A
• Cluster Member A validates the service ticket
• It then remembers, in memory, the mapping of the service ticket to the user's session
• The user requests to log out from the CAS Server

The CAS Server sends a logout request to the CAS service, but the Cluster Member B receives the logout request. It looks in its memory but does not find a session for Service Ticket A, because it only exists in Cluster Member A. This means, the user has not been logged out successfully.

Users looking for this functionality might consider looking in the JA-SIG JIRA queue and forums for solutions to this problem. In...