This is somewhat related to what Brian describes in WLS Session Cookie Overriding in an OAM/SSO Enabled Environment. Here, I want to quickly point one potential issue if you plan to implement Web SSO using Weblogic server as a SAML2.0 Service Provider (SP).
When configuring a Weblogic server instance for SAML2.0 services, you have to fill in a property called “Published Site URL”.
When this instance is an SP, this property tell the partner IdP (Identity Provider) where to post SAML Responses to. In the case of SAML2.0, that URL must be http://<server>:<port>/saml2, where <server> and <port> must refer to how the IdP recognizes the SP. In other words, if you have something like a load balancer in front of Weblogic server (which is the case if you’re running a cluster), <server> and <port> would be the load balancer’s. “saml2” is the web context of Weblogic’s internal SAML2.0 servlet, whose fully qualified name is com.bea.security.saml2.servlet.SAML2Servlet.
Very well, this servlet, when called as a Service Provider, has the ability to consume a SAML assertion created by the partner IdP and instantiate an HTTP session for the browser session in the server. And it will tie it to the browser session by issuing a cookie named JSESSIONID whose cookie-path is set to “/”. So what?
It turns out that many applications specify their own cookie-path to avoid the problem of JSESSIONID clashing, where last accessed applications by the browser override the JSESSIONID cookie value during the same browser session, thus leaving orphaned HTTP sessions in the server.
It also turns out that other applications use a different cookie name to avoid the same problem.
In both cases, the JSESSIONID cookie issued by saml2 servlet won’t be accepted by the application. You may be prompted for authentication again (this time by the application), get an HTTP 401-Unauthorized error or get into an infinite loop of redirects between SP and IdP.
The most obvious solutions to these problems is removing the cookie-path constraint from the application (in which case it defaults to "/") and having the application using the JSESSIONID name. You may need to get the blessings of your application provider for supportability purposes before proceeding to the changes.
That said, get to know your applications' cookies (cookie-name and cookie-path) before integrating them into WLS SAML2 SSO.