Web Socket not connecting to tornado server

Question

I am using the python tornado framework to write a small web server for a game I'm writing. The get requests are working fine however, when I try to create a websocket connection I get this error in my browser:

Here is my javascript code:

    var ws = new WebSocket("ws://localhost:8888/ws");
    ws.onopen = function() {
            ws.send("ping");
    };

Here is the code for the python server:

class StateQueryHandler(tornado.websocket.WebSocketHandler):
    def open(self):
        state.players = state.players + 1
        self.write(state.players)
        print("socket opened")

. . .

application = tornado.web.Application([
    (r"/ws", StateQueryHandler),#websocket endpoint
    (r"/static/(.*)", tornado.web.StaticFileHandler, {"path": "../client"})
])
server = tornado.httpserver.HTTPServer(application)
server.listen(8888)
tornado.ioloop.PeriodicCallback(state.update, 250).start()
tornado.ioloop.IOLoop.instance().start()

Can anyone tell me what is going wrong? Do I have to do anything extra on the server side to keep the tcp connection alive ?

Answer 1

Try this:

class StateQueryHandler(tornado.websocket.WebSocketHandler):
    def open(self):
        state.players = state.players + 1
        self.write_message(state.players)
        print("socket opened")

You need to call the method write_message, not write.

Check out the documentation for more info: http://www.tornadoweb.org/en/branch2.4/websocket.html