Create Chat in WebApplication Java

I have a java web application with servlet and java class in backend, and ajax and jsp in frontend that I deploy on Tomcat6. I would create a chat service for the users of my application. What kind of technology can I use?

I have a jsp footer.jsp that is common to other jsp p开发者_开发百科age, in this jsp I would create a popup like facebook for chat comunication. I have in the hashmap of context application the user logged, I don't know how create a java listner for send and recive message from user logged and other. what kind of technology I must use for create a backend and frontend listner?

It really depends on what you know / want to learn and also what functionallity the application should have... why not just add to your current application ? use JSP for the front end, use AJAX for communication - the servlet for the server .....

i think you would need some ajax long polling or Jabber.