WebSockets
aqui esta el link para revisar sobre la tematica http://www.html5rocks.com/es/tutorials/websockets/basics/ ejemplos http://www.sanwebe.com/2013/05/chat-using-websocket-php-socket http://www.phpbuilder.com/articles/application-architecture/optimization/creating-real-time-applications-with-php-and-websockets.html