Single Sign On (SSO) is the ability for users to authenticate to a single web application, and by means of a successful authentication, will successfully authenticate to multiple other applications without needing to be prompted at each one. Clustered SSO stores the authentication information in a clustered cache. This allows for applications on multiple different servers to share the information, and also makes the information resilient to a failure of one of the hosts.
Some of the supported SSO mechanisms (for example, Kerberos, PicketLink SAML) need valves to work correctly. Valves have a similar function as the servlet filters, but they are processed before the container managed authentication. Valves for web applications can be defined in the
jboss-web.xml deployment descriptor.