Simple example of a websocket server with Tornado

websocket_server.py

# While this code still works, I would recommend using Fast API for websockets in modern applications.
# See: https://fastapi.tiangolo.com/advanced/websockets/

# Note this is targeted at python 3
import tornado.web
import tornado.httpserver
import tornado.ioloop
import tornado.websocket
import tornado.options

LISTEN_PORT = 8000
LISTEN_ADDRESS = '127.0.0.1'


class ChannelHandler(tornado.websocket.WebSocketHandler):
    """
    Handler that handles a websocket channel
    """
    @classmethod
    def urls(cls):
        return [
            (r'/web-socket/', cls, {}),  # Route/Handler/kwargs
        ]
    
    def initialize(self):
        self.channel = None
    
    def open(self, channel):
        """
        Client opens a websocket
        """
        self.channel = channel
    
    def on_message(self, message):
        """
        Message received on channel
        """
    
    def on_close(self):
        """
        Channel is closed
        """
    
    def check_origin(self, origin):
        """
        Override the origin check if needed
        """
        return True
    
    
def main(opts):
    # Create tornado application and supply URL routes
    app = tornado.web.Application(ChannelHandler.urls())
    
    # Setup HTTP Server
    http_server = tornado.httpserver.HTTPServer(application)
    http_server.listen(LISTEN_PORT, LISTEN_ADDRESS)
    
    # Start IO/Event loop
    tornado.ioloop.IOLoop.instance().start()


if __name__ == '__main__':
    main()

@timsavage the "application" variable must be changed to "app" when setup this server 😄

How do I send to the websocket?

MDN have great docs on using WebSockets see https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_client_applications

While this approach will still work, I would recommend using FastAPI, they have great docs and a howto guide on using Web Sockets
See: https://fastapi.tiangolo.com/advanced/websockets/