The welcome page of a site is often a good place to add a gateway filter. The welcome page can be decorated with personal information if the visitor has validate CAS session. I.E. The visitor has previously authenticated themselves via CAS, cookies are enabled in the browser, and the TicketGrantingTicket has not expired.
The extent of the welcome page decoration is only limited by your imagination.
To fully understand a gateway request see http://www.jasig.org/cas/client-integration/gateway
Configuration of Filters
Assuming you have a standard web site layout, with protected and unprotected areas, you will need to two authentication filters and one validation filter.
The two authentication filters will need to be configured slightly different; One will have gateway set to true and to other will have gateway set to false.
Following are two snippets of xml explain how to configure a gateway and protected web site.
please excuse the bad diagrams
A simplistic view of a gateway call when user does not have a validate CAS session.