I plan to write a class WebsocketHandler that wrap the package websockets
This is the code :
import asyncio
import websockets
class WebsocketHandler:
__connection = None
def __init__(self):
asyncio.run(self.__setConnection())
async def __setConnection(self):
async with websockets.connect("ws://localhost/your/path") as websocket:
self.__connection = websocket
print("Connected")
def send(self, msg):
self.__connection.send(msg)
print("message Send")
ws = WebsocketHandler()
ws.send("message")
For the server part I have another finished script that works (tested with other scripts in other languages) that sends me a message when I have a new connection, when I receive a message and when I have a client disconnection.
When I try it the script connect successfully to my websocket server (script print Connected and on the server side I get a new connection).
I get then a warning in my script
RuntimeWarning: coroutine 'WebSocketCommonProtocol.send' was never awaited
self.__connection.send(msg)
And then my script print Message send and it stops.
The problem is that on the server side I don't receive the fact of having a message but only the one that tells me that the client is disconnected. Basically the script does not send the message and does not produce an error.
Anyone have any idea what the problem is ?
The problem is that the WebsocketHandler class has got only one async method, namely __setConnection, which is run by calling the asyncio.run function. The docs say that
This function always creates a new event loop and closes it at the
end.
That is, this is the only place where the async code could be running. Your code creates a websocket connection and closes it just after it prints "Connected". It happens because you call the websockets.connect method with async with as an asynchronous context manager which closes the connection automatically on exit. This is the first flaw, the second one is that the self.__connection.send function is a coroutine and it won't be running until you'll await on it. This is exactly what the error message is telling you about. Here is how you can fix the websocket handler class:
import asyncio
import websockets
class WebsocketHandler(object):
def __init__(self):
self.conn = None
async def connect(self, url):
self.conn = await websockets.connect(url)
async def send(self, msg):
await self.conn.send(msg)
async def close(self):
await self.conn.close()
async def main():
handler = WebsocketHandler()
await handler.connect('ws://localhost:8765')
await handler.send('hello')
await handler.send('world')
await handler.close()
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
Related
I try to create a websocket server, I wanna make a client to exchange data from server to client, but now my data from other process, I need to make a queue accept data from other process, it makes my main websocket function blocked, the final result is that could not reconnect after client connection break, I think it blocked in the code of queue.
Here is my part of my code:
class RecorderEventHook(object):
def __init__(self, high_event_mq):
self.high_event_mq = high_event_mq
self.msg = None
self.loop = None
# #wrap_keep_alive
async def on_msg_event(self, websocket):
try:
# async for message in websocket:
while True:
msg = self.high_event_mq.get()
await websocket.send(json.dumps(msg))
# msg
except Exception as error:
print(error)
async def event_controller(self):
await websockets.serve(self.on_msg_event, 'localhost', 8888)
def start(self):
loop = asyncio.new_event_loop()
loop.create_task(self.event_controller())
loop.run_forever()
I try to save connected websocket object and using in other thread(in same process), but it failed and mentions
"xxxx" function never waited
I want to be able to receive data from other processes without affecting the normal reconnection of the client.
Anybody help and big appreciate.
I am using the websocket library in Python and I am new to this.
I want to create multiple different connections to websockets. This happens through my custom WebsocketProcess class which opens the connection, receives the event, keeps a record Id and then calls an API to grab the information for this particular record.
I am having trouble running them in parallel.
Please, see below (ignore the numerous imports)
Main:
#if __name__ == "__main__":
async def main():
#The length AccessTokens, ClientDescriptions and SQLTablesFix determines how many websockets we need to open
L = await asyncio.gather(
properties[0].websocket_starting(AccessTokens[0], ClientDescriptions[0], SQLTablesFix[0]),
properties[1].websocket_starting(AccessTokens[1], ClientDescriptions[1], SQLTablesFix[1]),
...
...
)
asyncio.run(main())
The WebsocketProcess class is as follows:
class WebsocketProcess:
"""description of class"""
def on_error(self, ws, error):
#{Relevant Code Here}
def on_open(self, ws):
print("\nOn Open\n")
def run(*args):
while True:
try:
time.sleep(1)
except TimeoutError:
pass
ws.close()
def on_close(self):
#{Relevant Code Here}
def on_message(self, ws, message):
#{Relevant Code Here}
ws.close()
def connect_websocket(self, AccessToken, ClientDescription, SQLTablesFix):
ws = websocket.WebSocketApp("_______url_here_____",
on_open = self.on_open,
on_message = self.on_message,
on_error = self.on_error,
on_close = self.on_close,
cookie = "ClientToken=_______; AccessToken=%s" % AccessToken)
ws.run_forever()
async def websocket_starting(self, AccessToken, ClientDescription, SQLTablesFix):
print("\nwebsocket_starting")
self.AccessToken = AccessToken
self.ClientDescription = ClientDescription
self.SQLTablesFix = SQLTablesFix
self.connect_websocket(self.AccessToken, self.ClientDescription, self.SQLTablesFix)
As you can see from the above, I have changed the main to asynchronous to run multiple instances of the websocket_process class in parallel. It opens a connection to the first websocket and it stops there waiting for events, without proceeding to open a second websocket.
I tried making the WebsocketProcess class entirely asynchronous but the errors I am receiving an error specifying that coroutine 'run' was never awaited (in the connect_websocket method).
Do you guys have any suggestions on how to run multiple instances of the websocket_process class in parallel?
Thanks!
Your websocket operations are blocking operations, to use websocket in asyncio, use other async libraries like websockets, Tornado
I'm new to websockets and asyncio and I'm trying to get a simple example working. I would like to create a server that accepts connections from multiple clients and concurrently runs a loop that sends a message to every connection once a second. I'm also trying to use asyncio.run() which I believe is preferred to the get_event_loop() code on which many examples are based.
Here's my code so far:
import asyncio
import websockets
USERS = set()
async def register(websocket, path):
USERS.add(websocket)
await websocket.send("Successfully registered")
async def count():
count = 0
while True:
print(f"Iteration: {count}")
if USERS:
for user in USERS:
await user.send("Sending message back to client")
await asyncio.sleep(1)
count +=1
async def serve():
server = await websockets.serve(register, 'localhost', 8765)
await server.wait_closed()
print("Server closed")
async def main():
await asyncio.gather(count(), serve())
asyncio.run(main())
When I run this the count coroutine works until I make a connection from a client. At this point the connection is successfully registered but when I try to send a message back to the client in count() I get an error because the connection is already closed. How should I change my code to stop this from happening?
How should I change my code to stop this from happening?
The problem might be that your handler, the register coroutine, is returning immediately, which prompts websockets to close the connection. Try to change it like this:
async def register(websocket, path):
USERS.add(websocket)
await websocket.send("Successfully registered")
await asyncio.Event().wait()
If that helps, you can put the event in USERS along with websocket, so that you have a way to terminate the connection to the client when you want to.
I'm trying to implement a websocket client in python using websockets and the apparently mandatory asyncio which I never used before (and I have a hard time to understand...).
I've read a lot on the subject and saw (too) many examples here and everywhere, but I can't find a way to properly make a websocket client with a persistent connection.
I need to have a persistent connection because the commands need to be requested on the same connection, the first one being an authentication command.
The remote server is a 3rd party API I don't have any control over.
I suppose I could run an authentication request along with each command my program sends but that does not feel right to open > auth > request > close for each command instead of keeping one connection alive during the whole program's life
My implementation is a library using many classes and I need to wrap the websocket connector/handler in one of them
Here's what I have right now, based on examples I found here and there (with some obfuscated data) :
import json
import asyncio
from websockets import connect
URL = 'wss://server.com/endpoint'
class Websocket:
async def __aenter__(self):
self._conn = connect(URL)
self.websocket = await self._conn.__aenter__()
return self
async def __aexit__(self, *args, **kwargs):
await self._conn.__aexit__(*args, **kwargs)
async def send(self, message):
await self.websocket.send(message)
async def receive(self):
return await self.websocket.recv()
class Handler:
def __init__(self):
self.wws = Websocket()
self.loop = asyncio.get_event_loop()
def command(self, cmd):
return self.loop.run_until_complete(self.__async__command(cmd))
async def __async__command(self, cmd):
async with self.wws as echo:
await echo.send(json.dumps(cmd))
return await echo.receive()
def main():
handler = Handler()
foo = handler.command('authentication command')
print('auth: ', foo)
bar = handler.command('another command to run depending on the first authentication')
print('command: ', bar)
if __name__ == '__main__':
main()
Basically right now I get these answers (simplified and obfuscated) :
auth: Ok, authenticated
command: Command refused, not authenticated
I suppose my problem is that the block async with self.wws as echo: kind of create the connection, runs its code then drop it instead of keeping the connection alive. Since we are not using a usual __init__ here but some asyncio voodoo I don't understand, I'm kind of stuck.
I think your diagnosis is correct, the problem is that the async context manager it creating and closing a connection for each call of Handler.command ... really not want you want.
Instead you could just synchronously establish the websocket connection during the init of Handler and then store the connection websocket (instance of type WebSocketClientProtocol) as a class member for later use, as in this sample code:
import json
import asyncio
from websockets import connect
URL = 'ws://localhost:8000'
class Handler:
def __init__(self):
self.ws = None
self.loop = asyncio.get_event_loop()
# perform a synchronous connect
self.loop.run_until_complete(self.__async__connect())
async def __async__connect(self):
print("attempting connection to {}".format(URL))
# perform async connect, and store the connected WebSocketClientProtocol
# object, for later reuse for send & recv
self.ws = await connect(URL)
print("connected")
def command(self, cmd):
return self.loop.run_until_complete(self.__async__command(cmd))
async def __async__command(self, cmd):
await self.ws.send(json.dumps(cmd))
return await self.ws.recv()
def main():
handler = Handler()
foo = handler.command('authentication command')
print('auth: ', foo)
bar = handler.command('another command to run depending on the first authentication')
print('command: ', bar)
if __name__ == '__main__':
main()
I am trying to create a script in python that listens to multiple sockets using websockets and asyncio, the problem is that no matter what I do it only listen to the first socket I call.
I think its the infinite loop, what are my option to solve this? using threads for each sockets?
async def start_socket(self, event):
payload = json.dumps(event)
loop = asyncio.get_event_loop()
self.tasks.append(loop.create_task(
self.subscribe(event)))
# this should not block the rest of the code
await asyncio.gather(*tasks)
def test(self):
# I want to be able to add corotines at a different time
self.start_socket(event1)
# some code
self.start_socket(event2)
this is what I did eventually, that way its not blocking the main thread and all subscriptions are working in parallel.
def subscribe(self, payload):
ws = websocket.WebSocket(sslopt={"cert_reqs": ssl.CERT_NONE})
ws.connect(url)
ws.send(payload)
while True:
result = ws.recv()
print("Received '%s'" % result)
def start_thread(self, loop):
asyncio.set_event_loop(loop)
loop.run_forever()
def start_socket(self, **kwargs):
worker_loop = asyncio.new_event_loop()
worker = Thread(target=self.start_thread, args=(worker_loop,))
worker.start()
worker_loop.call_soon_threadsafe(self.subscribe, payload)
def listen(self):
self.start_socket(payload1)
# code
self.start_socket(payload2)
# code
self.start_socket(payload3)
Your code appears incomplete, but what you've shown has two issues. One is that run_until_complete accepts a coroutine object (or other kind of future), not a coroutine function. So it should be:
# note parentheses after your_async_function()
asyncio.get_event_loop().run_until_complete(your_async_function())
the problem is that no matter what I do it only listen to the first socket I call. I think its the infinite loop, what are my option to solve this? using threads for each sockets?
The infinite loop is not the problem, asyncio is designed to support such "infinite loops". The problem is that you are trying to do everything in one coroutine, whereas you should be creating one coroutine per websocket. This is not a problem, as coroutines are very lightweight.
For example (untested):
async def subscribe_all(self, payload):
loop = asyncio.get_event_loop()
# create a task for each URL
for url in url_list:
tasks.append(loop.create_task(self.subscribe_one(url, payload)))
# run all tasks in parallel
await asyncio.gather(*tasks)
async def subsribe_one(self, url, payload):
async with websockets.connect(url) as websocket:
await websocket.send(payload)
while True:
msg = await websocket.recv()
print(msg)
One way to efficiently listen to multiple websocket connections from a websocket server is to keep a list of connected clients and essentially juggle multiple conversations in parallel.
E.g. A simple server that sends random # to each connected client every few secs:
import os
import asyncio
import websockets
import random
websocket_clients = set()
async def handle_socket_connection(websocket, path):
"""Handles the whole lifecycle of each client's websocket connection."""
websocket_clients.add(websocket)
print(f'New connection from: {websocket.remote_address} ({len(websocket_clients)} total)')
try:
# This loop will keep listening on the socket until its closed.
async for raw_message in websocket:
print(f'Got: [{raw_message}] from socket [{id(websocket)}]')
except websockets.exceptions.ConnectionClosedError as cce:
pass
finally:
print(f'Disconnected from socket [{id(websocket)}]...')
websocket_clients.remove(websocket)
async def broadcast_random_number(loop):
"""Keeps sending a random # to each connected websocket client"""
while True:
for c in websocket_clients:
num = str(random.randint(10, 99))
print(f'Sending [{num}] to socket [{id(c)}]')
await c.send(num)
await asyncio.sleep(2)
if __name__ == "__main__":
loop = asyncio.get_event_loop()
try:
socket_server = websockets.serve(handle_socket_connection, 'localhost', 6789)
print(f'Started socket server: {socket_server} ...')
loop.run_until_complete(socket_server)
loop.run_until_complete(broadcast_random_number(loop))
loop.run_forever()
finally:
loop.close()
print(f"Successfully shutdown [{loop}].")
A simple client that connects to the server and listens for the numbers:
import asyncio
import random
import websockets
async def handle_message():
uri = "ws://localhost:6789"
async with websockets.connect(uri) as websocket:
msg = 'Please send me a number...'
print(f'Sending [{msg}] to [{websocket}]')
await websocket.send(msg)
while True:
got_back = await websocket.recv()
print(f"Got: {got_back}")
asyncio.get_event_loop().run_until_complete(handle_message())
Mixing up threads and asyncio is more trouble than its worth and you still have code that will block on the most wasteful steps like network IO (which is the essential benefit of using asyncio).
You need to run each coroutine asynchronously in an event loop, call any blocking calls with await and define each method that interacts with any awaitable interactions with an async
See a working e.g.: https://github.com/adnantium/websocket_client_server