JSP security

[<abhishek.kumar () paladion net>]

hi,

i'am posting for the first time on this list. i'am developing a J2EE application and i want to call some of the EJBs 
from JSP pages. i want to know how to control the "roles" that will be transferred from the JSP page to the EJB when i 
access it. will it be the "role" that i use to log into the application or can i change it.

abhishek