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#!/usr/bin/env python3
"""Protocol parser example."""
import argparse
import aiohttp
import collections
import asyncio
try:
import signal
except ImportError:
signal = None
MSG_TEXT = b'text:'
MSG_PING = b'ping:'
MSG_PONG = b'pong:'
MSG_STOP = b'stop:'
Message = collections.namedtuple('Message', ('tp', 'data'))
def my_protocol_parser(out, buf):
"""Parser is used with StreamParser for incremental protocol parsing.
Parser is a generator function, but it is not a coroutine. Usually
parsers are implemented as a state machine.
more details in asyncio/parsers.py
existing parsers:
* http protocol parsers asyncio/http/protocol.py
* websocket parser asyncio/http/websocket.py
"""
while True:
tp = yield from buf.read(5)
if tp in (MSG_PING, MSG_PONG):
# skip line
yield from buf.skipuntil(b'\r\n')
out.feed_data(Message(tp, None))
elif tp == MSG_STOP:
out.feed_data(Message(tp, None))
elif tp == MSG_TEXT:
# read text
text = yield from buf.readuntil(b'\r\n')
out.feed_data(Message(tp, text.strip().decode('utf-8')))
else:
raise ValueError('Unknown protocol prefix.')
class MyProtocolWriter:
def __init__(self, transport):
self.transport = transport
def ping(self):
self.transport.write(b'ping:\r\n')
def pong(self):
self.transport.write(b'pong:\r\n')
def stop(self):
self.transport.write(b'stop:\r\n')
def send_text(self, text):
self.transport.write(
'text:{}\r\n'.format(text.strip()).encode('utf-8'))
class EchoServer(asyncio.Protocol):
def connection_made(self, transport):
print('Connection made')
self.transport = transport
self.stream = aiohttp.StreamParser()
asyncio.Task(self.dispatch())
def data_received(self, data):
self.stream.feed_data(data)
def eof_received(self):
self.stream.feed_eof()
def connection_lost(self, exc):
print('Connection lost')
@asyncio.coroutine
def dispatch(self):
reader = self.stream.set_parser(my_protocol_parser)
writer = MyProtocolWriter(self.transport)
while True:
try:
msg = yield from reader.read()
except aiohttp.ConnectionError:
# client has been disconnected
break
print('Message received: {}'.format(msg))
if msg.tp == MSG_PING:
writer.pong()
elif msg.tp == MSG_TEXT:
writer.send_text('Re: ' + msg.data)
elif msg.tp == MSG_STOP:
self.transport.close()
break
@asyncio.coroutine
def start_client(loop, host, port):
transport, stream = yield from loop.create_connection(
aiohttp.StreamProtocol, host, port)
reader = stream.reader.set_parser(my_protocol_parser)
writer = MyProtocolWriter(transport)
writer.ping()
message = 'This is the message. It will be echoed.'
while True:
try:
msg = yield from reader.read()
except aiohttp.ConnectionError:
print('Server has been disconnected.')
break
print('Message received: {}'.format(msg))
if msg.tp == MSG_PONG:
writer.send_text(message)
print('data sent:', message)
elif msg.tp == MSG_TEXT:
writer.stop()
print('stop sent')
break
transport.close()
def start_server(loop, host, port):
f = loop.create_server(EchoServer, host, port)
srv = loop.run_until_complete(f)
x = srv.sockets[0]
print('serving on', x.getsockname())
loop.run_forever()
ARGS = argparse.ArgumentParser(description="Protocol parser example.")
ARGS.add_argument(
'--server', action="store_true", dest='server',
default=False, help='Run tcp server')
ARGS.add_argument(
'--client', action="store_true", dest='client',
default=False, help='Run tcp client')
ARGS.add_argument(
'--host', action="store", dest='host',
default='127.0.0.1', help='Host name')
ARGS.add_argument(
'--port', action="store", dest='port',
default=9999, type=int, help='Port number')
if __name__ == '__main__':
args = ARGS.parse_args()
if ':' in args.host:
args.host, port = args.host.split(':', 1)
args.port = int(port)
if (not (args.server or args.client)) or (args.server and args.client):
print('Please specify --server or --client\n')
ARGS.print_help()
else:
loop = asyncio.get_event_loop()
if signal is not None:
loop.add_signal_handler(signal.SIGINT, loop.stop)
if args.server:
start_server(loop, args.host, args.port)
else:
loop.run_until_complete(start_client(loop, args.host, args.port))
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