asyncws is a library for developing coroutine based websocket applications in Python 3.
It implements RFC 6455, passes the Autobahn Testsuite and supports SSL/TSL out of the box. Based on PEP 3156 and coroutines it makes it easy to write highly concurrent websocket based applications.
To install the package: python3 setup.py install
Echo server:
import asyncio
import asyncws
@asyncio.coroutine
def echo(websocket):
while True:
frame = yield from websocket.recv()
if frame is None:
break
yield from websocket.send(frame)
loop = asyncio.get_event_loop()
server = loop.run_until_complete(
asyncws.start_server(echo, '127.0.0.1', 8000))
try:
loop.run_forever()
except KeyboardInterrupt as e:
server.close()
loop.run_until_complete(server.wait_closed())
finally:
loop.close()Corresponding echo client:
import asyncio
import asyncws
@asyncio.coroutine
def echo(websocket):
while True:
yield from websocket.send('hello')
msg = yield from websocket.recv()
if msg is None:
break
print(msg)
loop = asyncio.get_event_loop()
websocket = loop.run_until_complete(
asyncws.connect('ws://localhost:8000'))
try:
loop.run_until_complete(echo(websocket))
except KeyboardInterrupt as e:
loop.run_until_complete(websocket.close())
loop.run_until_complete(websocket.wait_closed())
finally:
loop.close()The first step is to create the certificate and key files. A self-signed certificate can be created with a command like:
openssl req -newkey rsa:2048 -nodes -keyout example.key -x509 -days 365 -out example.crt
Create an SSLContext with the certificate and key just generated and then pass the context to start_server():
import asyncio
import asyncws
import ssl
@asyncio.coroutine
def echo(websocket):
while True:
frame = yield from websocket.recv()
if frame is None:
break
yield from websocket.send(frame)
ssl_context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
ssl_context.check_hostname = False
ssl_context.load_cert_chain('example.crt', 'example.key')
loop = asyncio.get_event_loop()
loop.set_debug(True)
server = loop.run_until_complete(
asyncws.start_server(echo, '127.0.0.1', 8000, ssl=ssl_context))
try:
loop.run_forever()
except KeyboardInterrupt as e:
server.close()
loop.run_until_complete(server.wait_closed())
finally:
loop.close()An SSLContext is needed to secure the client-side of the socket:
import asyncio
import asyncws
import ssl
@asyncio.coroutine
def echo(websocket):
while True:
yield from websocket.send('hello')
echo = yield from websocket.recv()
if echo is None:
break
print(echo)
ssl_context = ssl.create_default_context(ssl.Purpose.SERVER_AUTH)
ssl_context.check_hostname = False
ssl_context.verify_mode = ssl.CERT_NONE
ssl_context.load_verify_locations('example.crt')
loop = asyncio.get_event_loop()
websocket = loop.run_until_complete(
asyncws.connect('wss://localhost:8000', ssl=ssl_context))
try:
loop.run_until_complete(echo(websocket))
except KeyboardInterrupt as e:
loop.run_until_complete(websocket.close())
loop.run_until_complete(websocket.wait_closed())
finally:
loop.close()Now you have a fully encrypted websocket connection!