Single Sign on with Jasig CAS

[kastork]

Jasig CAS is a Single Sign On solution that is widely deployed in the education sector.

http://www.jasig.org/cas

Like many SSO solutions, the protocol is based on browser redirection and browser cookies. (It is similar to, but slightly different than, OAUTH and SAML)

I'm looking for a way to utilize such a system (in particular CAS) as the means for authenticating users to Union Server.

Example use-case:

1. Say one has a web site that uses CAS to authenticate user (perhaps using a framework, like Spring Security)
2. The site deploys within it some number of Orbiter clients that talk to a Union server running somewhere else
3. These orbiter clients should not be trusted by union without authentication -- also, the Union apps will need user information from the web site
4. The user must not be required to sign in to Union, since he's already signed in to the website.

Are there examples of how to accomplish this available? I'm interested in CAS, but examples for OAUTH2 and/or SAML would be useful too.