Background: The Central Authentication Service (CAS) is a single-sign-on / single-sign-off protocol for the web. It permits a user to access multiple applications while providing their credentials (such as userid and password) only once to a central CAS Server application.
https://apereo.github.io/cas/6.5.x/protocol/CAS-Protocol-Specification.html Note that it would only implement CAS 2.0, and does not support service/proxy ticket validation and proxy ticket service. And, it only supports http redirect callback and back-channel logout.
