Has anyone made any headway with coming up with a single sign on solution with Domain access to date for Drupal 7? I've been looking closely at two old modules, one no longer maintained (SSO for D6) and one still maintained (CAS). I've also read that SAML might be a key to unlocking this, but am uncertain. Facebook's FBConnect might be another option too or another way could be integrating OpenID from what I've read, and experienced on StackOverflow's sub sites.
I know that OpenID can do this since we are logged into all of *Overflows sub sites at the same time using one login. The question is how does it cross DNS servers? Does it handshake with one half of a matching hash? I cannot find any documentation on this, so am at a loss.
So, are there any solutions that are known to date, or information on what to start looking into? I think I've made a good point at the possibilities. I read this thread, Domain Access SSO but am uncertain to what version it pertains to (Drupal. DA, SSO or otherwise). It looks like the "Solution" is to create a master table set with users and permissions, then share those across the domains? How might this work if there are already multiple sites created under Domain Access? Would you clone and rebuild the entire installation, or would you need to start from scratch? It really raises more questions than answers. I contacted the author with no response, so the questions still stand.
Any opinions out there on the who what or why would be greatly appreciated, I just need a start point to get the ball rolling. Thanks everyone.