gistfile1.py

class WebSocketHandler(tornado.websocket.WebSocketHandler):
    _PING_INTERVAL = 3.0
    _DISCONNECT_TIMEOUT = 10.0

    connections = set()
    button = Button()

    def open(self):
        self.id = self.get_argument("id")
        WebSocketHandler.connections.add(self)
        self._add_periodic_ping()
        self._add_cleanup_timeout()
        WebSocketHandler.broadcast_connections(self)

    def _add_periodic_ping(self):
        self._periodic_ping = tornado.ioloop.PeriodicCallback(
            functools.partial(self.ping, "0"), self._PING_INTERVAL * 1000.0)
        self._periodic_ping.start()