How can I implement asyncio websockets in a class?

How to write async programs?

1. You should define async funcs with async
2. You should call asyncfuncs with await
3. You need event loop to start your async program

All other is almost same as with regular Python programs.

import asynciofrom websockets import connectclass EchoWebsocket:    async def __aenter__(self):        self._conn = connect("wss://echo.websocket.org")        self.websocket = await self._conn.__aenter__()                return self    async def __aexit__(self, *args, **kwargs):        await self._conn.__aexit__(*args, **kwargs)    async def send(self, message):        await self.websocket.send(message)    async def receive(self):        return await self.websocket.recv()async def main():    async with EchoWebsocket() as echo:        await echo.send("Hello!")        print(await echo.receive())  # "Hello!"if __name__ == '__main__':    loop = asyncio.get_event_loop()    loop.run_until_complete(main())

Output:

Hello!

As you see, code is almost same as you wrote.

Only difference is that websockets.connect designed to be async context manager (it uses __aenter__, __aexit__). It's necessary to release connection and will also help you to make async operations during class initialization (since we have no async version of __init__).

I advise you to organize your class same way. But if you really don't want to use context manager for some reason you can use new __await__ method to make async initialization and some other async function to release connection:

import sysimport asynciofrom websockets import connectclass EchoWebsocket:    def __await__(self):        # see: http://stackoverflow.com/a/33420721/1113207        return self._async_init().__await__()    async def _async_init(self):        self._conn = connect("wss://echo.websocket.org")        self.websocket = await self._conn.__aenter__()        return self    async def close(self):        await self._conn.__aexit__(*sys.exc_info())    async def send(self, message):        await self.websocket.send(message)    async def receive(self):        return await self.websocket.recv()async def main():    echo = await EchoWebsocket()    try:        await echo.send("Hello!")        print(await echo.receive())  # "Hello!"    finally:        await echo.close()if __name__ == '__main__':    loop = asyncio.get_event_loop()    loop.run_until_complete(main())

Many examples of using websockets you can find in it's docs.