By OPA I assume we are talking about Web Determinations.
There is no built in Authentication for Web Determinations, but the way you should implement it is via a custom event handler. If you implement an OnRequestEvent (which fires when ever a request is made to web determinations) you can pass a user off to a login page initially (on start session), and then check that the user is authenticated when any subsequent request is made.
OnRequestEvent is a Web Determinations Servlet event. For more information, have a look at "Events and Event Handlers" in the Oracle Policy Automation Developer's Guide [http://docs.oracle.com/html/E36316_01/toc.htm]
Edited by: frank.hampshire on Aug 31, 2012 11:36 AM