tornado 403 GET warning when opening websocket

please add

def check_origin(self, origin):
    return True

in class MyHandler like this

class MyHandler(tornado.websocket.WebSocketHandler):

    def check_origin(self, origin):
        return True

    def open(self):
        print "connection opened"
        self.write_message("connection opened")

    def on_close(self):
        print "connection closed"

    def on_message(self,message):
        print "Message received: {}".format(message)
        self.write_message("message received")

From the DOCs:

By default, [check_origin] rejects all requests with an origin on a host other than
this one.

This is a security protection against cross site scripting attacks on
browsers, since WebSockets are allowed to bypass the usual same-origin
policies and don’t use CORS headers.

And again:

This is an important security measure; don’t disable it without
understanding the security implications. In particular, if your
authentication is cookie-based, you must either restrict the origins
allowed by check_origin() or implement your own XSRF-like protection
for websocket connections. See these articles for more.

Link.