Newbie: JSF and Tomcat Authentication

I think this may be a silly question, and i'm missing something obvious, but please help if you can....

I'm authenticating the user with tomcat and a MySQL database. Once they authenticate they are directed to my jsf page.

How can i get the username/id of the person that has logged?

This needs to be displayed on my page

any help appreciated

[375 byte] By [PaulHunter5a] at [2007-10-3 4:53:10]