Java EE (Java Enterprise Edition) General Discussion

hi
i am developing jsp page
i completed except logout.jsp page

my login page is in Jsp format and then business Logic in servlet and then get method & set method in bean.java

i have login and then it sucess page there i have singout button
if i sign out it should go to login page
how to do
how to make session invalidate
how to get session id
i have one more doubt i should check session invalidate each jsp page
regarding session login and logout in jsp
if anybody knows please give me a piece of code regarding login and logout

Regards
Akshatha