I am trying to customize a Java EE web application (developed using velocity) that uses Shibboleth authentication mechanism. However, I have been asked to provide SSO authentication without using sessions. The user signs into one portal and gets authenticated. In the same portal, he clicks the link to another portal. I am supposed to customize it such that authentication can be checked via URL directly. Second portal has its own database that contains user names and their respective roles. The two things I am not sure about are:-
How would the second portal realize if the user signs out of the first portal?
How would the second portal realize if the user has just copied the URL from some previous access to first portal?
Is there any way to get around these problems?