How to use autobahn sendmessage() from seperate thread (asyncio)?

Question

I want to use sendMessage() from outside the MyServerProtocol from a separate thread to send a message to the client.

I am trying something very similar to this and this, which did not work.

The first solution uses twisted and the second uses `broadcast_message()' which throws the following error

for c in set(cls.connections):
AttributeError: type object 'MyServerProtocol' has no attribute 'connections'

My code:

class MyServerProtocol(WebSocketServerProtocol):
    loop = None

    def onConnect(self, request):
        print("Client connecting: {0}".format(request.peer))

    def onOpen(self):
        print("WebSocket connection open.")

    def onMessage(self, payload, isBinary):
        if isBinary:
            print("Binary message received: {0} bytes".format(len(payload)))
        else:
            print("Text message received: {0}".format(payload.decode('utf8')))

    def onClose(self, wasClean, code, reason):
        print("WebSocket connection closed: {0}".format(reason))

    @classmethod
    def broadcast_message(cls, data):
        payload = bytes(data, encoding='utf8')
        for c in set(cls.connections):
            self.loop.call_soon_threadsafe(cls.sendMessage, c, payload)

if __name__ == '__main__':
    import asyncio
    factory = WebSocketServerFactory(u"ws://127.0.0.1:9080")
    factory.protocol = MyServerProtocol
    loop = asyncio.get_event_loop()
    MyServerProtocol.loop = loop
    coro = loop.create_server(factory, '0.0.0.0', 9080)
    server = loop.run_until_complete(coro)
    vad_thread = threading.Thread(target=main, args=(ARGS,))
    vad_thread.start()

    try:
        loop.run_forever()
        print("this will not print")
    except KeyboardInterrupt:
        pass
    finally:
        server.close()
        loop.close()

From vad_thread, I called:

MyServerProtocol.broadcast_message(payload)

which throws above mentioned error.

I want a function, say send_message(payload) which sends the payload to the client.