Hi... I am making the fomous and well known : "Chat Program"

I want to do it with servlets and applets. I did some research and I founf that servlets take post from an HTML page to comunicate with the client. With an Applet you could send data thru a URL object and get it in the servlets like if it were a GET POST. So.. far.. I am doing ok. Now... how do I comunicate from the Servlet to the Applet?!?!?! Any ideas?

Thank you for any help!