Python 3.4+Async programmingterm

asyncio.DatagramProtocol

protocols and transports

The protocol for datagrams (UDP): the loop calls datagram_received(data, addr) for every packet and error_received() on a send or receive error.

Syntax

transport, protocol = await loop.create_datagram_endpoint(ProtocolClass, local_addr=...)

asyncio has no high-level streams API for UDP, so DatagramProtocol is the only built-in route. Unlike TCP, message boundaries survive: one sendto() means one datagram_received(), but delivery and order are not guaranteed. Send with transport.sendto(), not write(); error_received() often signals an ICMP 'port unreachable' after sendto() to a closed port.

Examples

import asyncio
class Collector(asyncio.DatagramProtocol):
    def datagram_received(self, data, addr):
        print('пакет', data)  # → пакет b'one' / пакет b'two'
async def main():
    loop = asyncio.get_running_loop()
    server, _ = await loop.create_datagram_endpoint(Collector, local_addr=('127.0.0.1', 0))
    addr = server.get_extra_info('sockname')
    client, _ = await loop.create_datagram_endpoint(
        asyncio.DatagramProtocol, remote_addr=addr)
    client.sendto(b'one')
    client.sendto(b'two')
    await asyncio.sleep(0.01)
    client.close()
    server.close()
asyncio.run(main())

See also

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