Python websockets send ping

(CkPython) Send a WebSocket Ping Control Frame

«At any point after the handshake, either the client or the server can choose to send a ping to the other party. When the ping is received, the recipient must send back a pong as soon as possible. You can use this to make sure that the client is still connected, for example. A ping or pong is just a regular frame, but it’s a control frame. Pings have an opcode of 0x9, and pongs have an opcode of 0xA. When you get a ping, send back a pong with the exact same Payload Data as the ping (for pings and pongs, the max payload length is 125). You might also get a pong without ever sending a ping; ignore this if it happens.»

This example demonstrates how to send a Ping in the midst of sending a message.

Note: The websockets.chilkat.io server imposes the following limitations:
Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.

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import sys import chilkat # This example requires the Chilkat API to have been previously unlocked. # See Global Unlock Sample for sample code. ws = chilkat.CkWebSocket() # The PongAutoConsume property is True by default. This means that any Pong frames that are received # will automatically be consumed, and the ReadFrame method will continue reading the next incoming frame before it returns. ws.put_PongAutoConsume(True) # For brevity, this example does not check for errors when etablishing the WebSocket connection. # See Establish WebSocket Connection for more complete sample code for making the connection. rest = chilkat.CkRest() # Connect to websockets.chilkat.io # IMPORTANT: websockets.chilkat.io accepts frames of up to 16K in size and echoes them back. # IMPORTANT: The websockets.chilkat.io server imposes the following limitations: # ---------- Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages. success = rest.Connect("websockets.chilkat.io",80,False,False) ws.UseConnection(rest) ws.AddClientHeaders() responseBodyIgnored = rest.fullRequestNoBody("GET","/wsChilkatEcho.ashx") success = ws.ValidateServerHandshake() if (success != True): print(ws.lastErrorText()) sys.exit() # This example sends a multi-frame message to the Chilkat echo server, and reads the response. # In the midst of sending the message, we'll send a Ping control frame. The server should respond with a Pong frame, # and we'll automatically consume it. # Send the 1st frame in the message. finalFrame = False success = ws.SendFrame("This is the 1st frame\r\n",finalFrame) if (success != True): print(ws.lastErrorText()) sys.exit() # Let's send a Ping frame here. success = ws.SendPing("This is a ping") if (success != True): print(ws.lastErrorText()) sys.exit() # Send the 2nd frame in the message. success = ws.SendFrame("This is the 2nd frame\r\n",finalFrame) if (success != True): print(ws.lastErrorText()) sys.exit() # Send the 3rd and final frame in the message. finalFrame = True success = ws.SendFrame("This is the 3rd and final frame\r\n",finalFrame) if (success != True): print(ws.lastErrorText()) sys.exit() # Read an incoming frames until we receive the final frame. # Note: It may be that the echo server (websockets.chilkat.io) responds with # the full message in a single final frame. # # The Pong response will be consumed automatically because the PongAutoConsume property is True. # Therefore, we don't need to worry about handling an incoming Pong. receivedFinalFrame = False while receivedFinalFrame == False : success = ws.ReadFrame() if (success != True): print("Failed to receive a frame") print("ReadFrame fail reason = " + str(ws.get_ReadFrameFailReason())) print(ws.lastErrorText()) sys.exit() receivedFinalFrame = ws.get_FinalFrame() # Show the opcode and final frame bit for the frame just received: print("Frame opcode: " + ws.frameOpcode()) print("Final frame: " + str(receivedFinalFrame)) print("--") # Return the message accumulated in the above calls to ReadFrame. receivedMsg = ws.getFrameData() print("Received: " + receivedMsg) # Close the websocket connection. success = ws.SendClose(True,1000,"Closing this websocket.") if (success != True): print(ws.lastErrorText()) sys.exit() # Read the Close response. success = ws.ReadFrame() if (success != True): print("ReadFrame fail reason = " + str(ws.get_ReadFrameFailReason())) print(ws.lastErrorText()) sys.exit() # Should receive the "Close" opcode. print("Received opcode: " + ws.frameOpcode()) # Should be the same status code we sent (1000) print("Received close status code: " + str(ws.get_CloseStatusCode())) # The server may echo the close reason. If not, this will be empty. print("Echoed close reason: " + ws.closeReason()) print("Success.")

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Both sides#

What does ConnectionClosedError: no close frame received or sent mean?#

connection handler failed Traceback (most recent call last): . asyncio.exceptions.IncompleteReadError: 0 bytes read on a total of 2 expected bytes The above exception was the direct cause of the following exception: Traceback (most recent call last): . websockets.exceptions.ConnectionClosedError: no close frame received or sent 

Traceback (most recent call last): . ConnectionResetError: [Errno 54] Connection reset by peer The above exception was the direct cause of the following exception: Traceback (most recent call last): . websockets.exceptions.ConnectionClosedError: no close frame received or sent 

• End-user devices tend to lose network connectivity often and unpredictably because they can move out of wireless network coverage, get unplugged from a wired network, enter airplane mode, be put to sleep, etc.
• HTTP load balancers or proxies that aren’t configured for long-lived connections may terminate connections after a short amount of time, usually 30 seconds, despite websockets’ keepalive mechanism.

If you’re facing a reproducible issue, enable debug logs to see when and how connections are closed.

What does ConnectionClosedError: sent 1011 (unexpected error) keepalive ping timeout; no close frame received mean?#

If you’re seeing this traceback in the logs of a server:

connection handler failed Traceback (most recent call last): . asyncio.exceptions.CancelledError The above exception was the direct cause of the following exception: Traceback (most recent call last): . websockets.exceptions.ConnectionClosedError: sent 1011 (unexpected error) keepalive ping timeout; no close frame received 

or if a client crashes with this traceback:

Traceback (most recent call last): . asyncio.exceptions.CancelledError The above exception was the direct cause of the following exception: Traceback (most recent call last): . websockets.exceptions.ConnectionClosedError: sent 1011 (unexpected error) keepalive ping timeout; no close frame received 

it means that the WebSocket connection suffered from excessive latency and was closed after reaching the timeout of websockets’ keepalive mechanism.

You can catch and handle ConnectionClosed to prevent it from being logged.

There are two main reasons why latency may increase:

See the discussion of timeouts for details.

If websockets’ default timeout of 20 seconds is too short for your use case, you can adjust it with the ping_timeout argument.

How do I set a timeout on recv() ?#

async with asyncio.timeout(timeout=10): message = await websocket.recv() 

On older versions of Python, use asyncio.wait_for() :

message = await asyncio.wait_for(websocket.recv(), timeout=10) 

This technique works for most APIs. When it doesn’t, for example with asynchronous context managers, websockets provides an open_timeout argument.

How can I pass arguments to a custom protocol subclass?#

You can bind additional arguments to the protocol factory with functools.partial() :

import asyncio import functools import websockets class MyServerProtocol(websockets.WebSocketServerProtocol): def __init__(self, *args, extra_argument=None, **kwargs): super().__init__(*args, **kwargs) # do something with extra_argument create_protocol = functools.partial(MyServerProtocol, extra_argument=42) start_server = websockets.serve(. , create_protocol=create_protocol) 

This example was for a server. The same pattern applies on a client.

How do I keep idle connections open?#

websockets sends pings at 20 seconds intervals to keep the connection open.

It closes the connection if it doesn’t get a pong within 20 seconds.

You can adjust this behavior with ping_interval and ping_timeout .

How do I respond to pings?#

Don’t bother; websockets takes care of responding to pings with pongs.

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