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.
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 have a problem with Telethon. I have a NewMessage() event listener, and it works just fine. But when exit the script with CTRL + C and start it again, it does not connect to the chat again.
I have to manually delete the connection in the Telegram app.
My question is:
How can I force the client to disconnect, when I press CTRL + C or when the program is closed.
from telethon import TelegramClient, events, sync
import globals, asyncio
client = TelegramClient('anon',
globals.api_id, globals.api_hash)
#client.on(events.NewMessage(chats=globals.tLink))
async def my_event_handler(event):
print(event.raw_text)
client.start()
client.run_until_disconnected()
If you need to repeatedly restart the script, it might be reasonable to not create a separate/new session for every run. Try using None to not create a .session file, instead of creating an anon.session.
client = TelegramClient(None, globals.api_id, globals.api_hash)
This is how I do it:
async def enviar():
(code)
async def main():
global ME
ME = await info_me();
enviar_var = asyncio.create_task(enviar());
await enviar_var;
with client:
try:
client.loop.run_until_complete(main());
except:
print("Encerrando...");
future = asyncio.Future();
future.set_result("1");
con.close();#I am using a SQLite database, you can ignore this line
print("Adeus!");
In Python, I'm using "websockets" library for websocket client.
import asyncio
import websockets
async def init_sma_ws():
uri = "wss://echo.websocket.org/"
async with websockets.connect(uri) as websocket:
name = input("What's your name? ")
await websocket.send('name')
greeting = await websocket.recv()
The problem is the client websocket connection is disconnected once a response is received. I want the connection to remain open so that I can send and receive messages later.
What changes do I need to keep the websocket open and be able to send and receive messages later?
I think your websocket is disconnected due to exit from context manager after recv().
Such code works perfectly:
import asyncio
import websockets
async def init_sma_ws():
uri = "wss://echo.websocket.org/"
async with websockets.connect(uri) as websocket:
while True:
name = input("What's your name? ")
if name == 'exit':
break
await websocket.send(name)
print('Response:', await websocket.recv())
asyncio.run(init_sma_ws())
In your approach you used a asynchronous context manager which closes a connection when code in the block is executed. In the example below an infinite asynchronous iterator is used which keeps the connection open.
import asyncio
import websockets
async def main():
async for websocket in websockets.connect(...):
try:
...
except websockets.ConnectionClosed:
continue
asyncio.run(main())
More info in library's docs.
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())
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