Encapsulation the API to a synchronous one

[galah92]

Hi,

I'm trying to use this library and essentially export a synchronous API, and thus creating a library to be used from matlab.

Essentially, I want start(), stop(), send(), recv() functions, where queues will be used in order to make the send() & recv() sync.

My current code (simplified) is:

class WebsocketServer():

    def __init__(self):
        self._server = None
        self._clients = set()
        self._loop = None

    def start(self, port=1234):
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        self._loop = loop
        start_server = websockets.serve(self._handle_client,
                                        host='localhost',
                                        port=port,
                                        loop=loop)
        self._server = loop.run_until_complete(start_server)

    def stop(self):
        if self._server:
            self._server.close()
            self._server = None
            self._clients.clear()

    async def _handle_client(self, client, path):
        try:
            self._clients.add(client)
            async for buffer in client:
                await self._handle_buffer(client, buffer)
        finally:
            self._clients.remove(client)

    async def _handle_buffer(self, client, buffer):
        print(buffer)
        await client.send(buffer)


def main():
    server = WebsocketServer()
    server.start()
    asyncio.get_event_loop().run_forever()


if __name__ == '__main__':
    main()

Running this directly (using main()) works well, but calling server = WebsocketServer(); server.start() does not.

I'm starting a new event loop because without calling run_forever() the server isn't able to accept connections, and with it the API client (the matlab) is blocked. This approach also doesn't work, and I can't seem to understand why.

I guess it's more of an asyncio question but it's heavily related to the library, hope you can help. Thanks!

[aaugustin]

I'm not 100% sure how you want to use this, but I can't see how it would work without a thread running the event loop.

The server needs loop.run_forever() to be running in order to work correctly. I would start it in a background thread.

Look at call_soon_threadsafe() to communicate between your library and the background thread, else you'll have problems.