Does asyncio from python support coroutine-based API for UDP networking?

Question

I was browsing the python asyncio module documentation this night looking for some ideas for one of my course projects, but I soon find that there might be a lack o

Answer 1

The reason a stream-based API is not provided is because streams offer ordering on top of the callbacks, and UDP communication is inherently unordered, so the two are fundamentally incompatible.

But none of that means you can't invoke coroutines from your callbacks - it's in fact quite easy! Starting from the EchoServerProtocol example, you can do this:

def datagram_received(self, data, addr):
    loop = asyncio.get_event_loop()
    loop.create_task(self.handle_income_packet(data, addr))

async def handle_income_packet(self, data, addr):
    # echo back the message, but 2 seconds later
    await asyncio.sleep(2)
    self.transport.sendto(data, addr)

Here datagram_received starts your handle_income_packet coroutine which is free to await any number of coroutines. Since the coroutine runs in the "background", the event loop is not blocked at any point and datagram_received returns immediately, just as intended.

Answer 2

You might be interested in this module providing high-level UDP endpoints for asyncio:

async def main():
    # Create a local UDP enpoint
    local = await open_local_endpoint('localhost', 8888)

    # Create a remote UDP enpoint, pointing to the first one
    remote = await open_remote_endpoint(*local.address)

    # The remote endpoint sends a datagram
    remote.send(b'Hey Hey, My My')

    # The local endpoint receives the datagram, along with the address
    data, address = await local.receive()

    # Print: Got 'Hey Hey, My My' from 127.0.0.1 port 50603
    print(f"Got {data!r} from {address[0]} port {address[1]}")