Implementing Single Logout Service a possibility?

[grillonbleu]

Hi!

You mention in the README that "If a user logs out from Moodle, it will not log them out from their SP application. The logout process is one-directional, from the SP app to Moodle". On the other hand, SAML defines a Single Logout process so that logging out from the IdP provokes a log out on the SPs as well.

Have you investigated what's needed to implement Single Logout? Are there any reasons that make it impossible? If it's just a matter of getting the work done, I might be able to work on a pull request.

[iv-enovation]

Hi
It should be possible to implement a frontchannel SLO via the Moodle plugin - to include a textarea for SLO URLs in the plugin configuration and then open all the URLs from it on the plugin's logout page in iframes.
A tiny issue with this approach is that the SLO URLs will have to logout users without issuing any redirects, and given Moodle-Moodle integration, an SP Moodle is not really able to do so
On the other hand, SimpleSAMLphp might include own SLO mechanisms, that is still to be investigated