I'm an expert in your question, so if you will allow me to teach you a little bit? You know the network capabilities of Java are pretty strong. Still, Java is a little bit confusing regarding games. I've developed Java desktop games professionally for the past three years now and I never truly got the feeling that Java likes games. If it did your question would not be necessary.
You're looking for a client class with this method
getGameSession()
...and this...
AnimationData a = transmitAnimationData(a)
which you call every 2 seconds or so.
Tell you what? It doesn't exist cause Sun have never created the GameClient and a GameServlet classes. They should be in the J2SE and J2EE APIs respectively. They aren't. So your task is now to write them and post them to Sun. Thank you. (If you need help, please say so. I'll watch this topic.)