import asyncio
import sys


USE_PROACTOR = True


async def _():
    await asyncio.sleep(.1)


class Protocol(asyncio.DatagramProtocol):

    def error_received(self, ex):
        print(ex)
        
    def datagram_received(self, data, addr):
        print("datagram received", data)
        

if USE_PROACTOR:
    loop = asyncio.new_event_loop()
else:
    loop = asyncio.SelectorEventLoop()
    asyncio.set_event_loop(loop)
    

async def create_server():
    return (await loop.create_datagram_endpoint(
        Protocol,
        local_addr=('127.0.0.1', 8000),
    ))[0]
server_transport = loop.run_until_complete(create_server())


async def create_client():
    return (await loop.create_datagram_endpoint(
        asyncio.DatagramProtocol,
        local_addr=('127.0.0.1', 8001),
    ))[0]
client_transport = loop.run_until_complete(create_client())


client_transport.sendto(b'ping 1', addr=('127.0.0.1', 8000))
loop.run_until_complete(_())


server_transport.sendto(b'pong', addr=('127.0.0.1', 8001))
loop.run_until_complete(_())


client_transport.sendto(b'ping 2', addr=('127.0.0.1', 8000))
loop.run_until_complete(_())


server_transport.sendto(b'pong', addr=('127.0.0.1', 8003))
loop.run_until_complete(_())


client_transport.sendto(b'ping 3', addr=('127.0.0.1', 8000))
loop.run_until_complete(_())


server_transport.close()
client_transport.close()
loop.run_until_complete(_())