This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
If you are checking the session , for each request thru action class, then by chance the user clicks on back button and got the previous page, he cant do anything, because session has been expired and he cant perform any activity, he need to login again !!