Glassfish 3.1.1中的Java EE Web应用程序异步登录

I'm trying to implement asynchronous login to JEE6 webapp using javascript and XMLHttpRequest. I should be able to make an asynchronous call with XMLHttpRequest to /app/j_security_check and parse the response somehow so that I can show the user a dialog with "Login Failed" or "Login success". I am using Glassfish 3.1.1.I'm trying to implement asynchronous login to J