This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
have u set the "authenticate"'s attribute before the page? if you haven't...then it is because the command : if getAttribute("authenticate")== null will always return null value, so it wil continuously direct you to the same page over and over again ( due to the response.sendredirect command