title: How does CAS Authentication and Facebook connect for SSO works?
body: <p>I have a question, less pertaining to actual implementation more towards "how it works".
  We have a CAS server doing the SSO authentication for multiple web protals (sister protals). How does CAS validates the cookies across portals and how does it figure out that user was logged onto sister site.</p>
  
  <p>Also extending same question to; can someone elaborate or point me to some documentation; that how does FACEBOOK Connect works with third party cookies?
  My question are:
  1. Can you really read third party cookies?
  2. How does your site know (if it implements facebook connect) that user is logged onto facebook?
  3. I am guessing that JS provided by Facebook would probably validate it; but would it be able to read those cookies, left by facebook, even though that JS is included in my portal?</p>
  
  <p>Maybe I am unclear, but it's because I am not really getting the hang of Single Sign on funda. If someone could explain me how these things interchangeably works; I'd be really grateful.</p>
  
  <p>Cheers</p>