Communicate the server-side tech with arduino

Hi everyone, Recently I have gotten a lot of help here, thank you for those helped me. I am going to remotely control a robot, and want to use the J2EE technology. Maybe using a web server to communicate and control the robot.

Can somebody tell me how will arduino communicate with the web server? What standards are out there for data communication in this way? Is XML needed ?

Thank you~~ :D

The below has some info on controlling a wireless bot via a web page.