Window popup in agent's session whenever user clicks button in his session

Question

How can I make a window popup in agent's session whenever a user clicks on a button in his session?
I need to add a functionality in my web application which pops up a window in a particular agent' session whenever a user clicks on a particular button in his session. That is when a user clicks on the button it signifies a request and an agent is notified of user's request and he should get a screen popup to show user's info.
Could any tell how can I achieve this functionality?
My web application uses following technologies:
JAVA, JSP, STRUTS, TILES, HIBERNATE
TOMCAT as server and MySql as Database.
Thanks,
Rajiv

Answer 1

What is the name of the session variable that you are creating on login? When he clicks logout, set that session variable to null. Like session.setAttribute("userName",null); and check for non-null condition before proceeding with any functionality in your jsp's.
What is the second question? You want to prevent duplicate logins from different systems? You would have to maintain a static datastructure like a HashMap for instance. Everytime a user logs in, put an entry into the HashMap...like userMap.put("userName","userName"); If an entry already exists, throw a message saying that user already logged in from another machine...