"I guess that the SSO Handler is called only when we have an anonymous user." yes.
"As far as I know, the eZSession is creating a cookie for each domain name while we are expecting just one."
PHP is controlling this, so you can't do anything about it unless they are all subdomains of one base domain. Try the redirect loop SSO stuff in ezvlogin extension, it loops over all the domains on login and logs the user in on all sites. So the user has a uniqe session on all domains as one would expect.
However, we still have an issue on the session side. We set some data in the $_SESSION value before login in and after those data has disappeared. Any idea ?
The data will not be shared as they have different sessions on all sites, you can however use ezpreference. If your talking about loosing session data on login on the same server, then your probably on 4.1.0? (known issue there)
Yes, just download updated version of ezsession.php (Only needed for 4.1.0!): http://pubsvn.ez.no/nextgen/stable/4.1/lib/ezutils/classes/ezsession.php
But, there are plenty of things fixed in 4.1.1 and 4.1.2 (and a 4.1.2 regression in 4.1.3), so you really should update. And remember, it's just a matter of updating the files, run the sql updates and clear some cache. It's not like 4.0.1 / 4.0.2 update unfortunately was.
ezpreferences are user centric instead of session centric, so better for your scenario maybe. But I don't know what your using it for, as I have a hard time understanding what you need to share between the sites that you choose to use session for:)
Actually, we are in eZ 4.1.3. :-/ The point is that we are doing things in a website, we redirect to another website and then we comeback to continue the stuff we were doing :
At step 1, we got some data in a session varaible ($_SESSION['mydata']), but at step3, those data has disappered. Our investigation leads us to the conclusion that eZPublish makes a kinf of reset for the session.
Not exactly.
We want to redirect to another website that is centralizing susbscriptions. But when we come back from this website, the session is "cleaned".