Websocket Demos

Install dependencies:

poetry install

Increased Backpressure Demo

This demonstrates an increase in the backpressure of a websocket connection by sending messages faster than they can be processed.

Eventually the connection is closed with either one of these generic errors:

• A 1006 error code on the server side (connection was closed abnormally) and the same on the client side.

• A 1011 error code (internal error). The client fails immediately after the connection is closed.

Observations

Server state / lost messages

Even though the underlying TCP guarantees the delivery of the messages, that does not mean the client has a chance to process all messages received in this demo. When the connection is timed out, the client drops remaining messages in the buffer, even though they are marked as delivered.

Execution

# Start the server
poetry run python server.py

# Start the client
poetry run python client.py

Output

Server

#...
2023-12-04 10:03:37.557 | INFO     | __main__:echo:26 - Sent message #1304
2023-12-04 10:03:37.581 | INFO     | __main__:echo:26 - Sent message #1305
2023-12-04 10:03:37.604 | INFO     | __main__:echo:26 - Sent message #1306
2023-12-04 10:04:05.961 | ERROR    | __main__:echo:32 - Connection with client closed:
2023-12-04 10:04:05.961 | ERROR    | __main__:echo:33 - no close frame received or sent

Client

#...
2023-12-04 10:04:15.039 | INFO     | __main__:slow_processing:16 - Received message with 9,858 chars
2023-12-04 10:04:16.041 | INFO     | __main__:slow_processing:16 - Received message with 10,303 chars
2023-12-04 10:04:17.042 | INFO     | __main__:slow_processing:16 - Received message with 10,370 chars
2023-12-04 10:04:18.043 | ERROR    | __main__:slow_processing:21 - Connection with server closed:
2023-12-04 10:04:18.044 | ERROR    | __main__:slow_processing:22 - sent 1011 (internal error) keepalive ping timeout; no close frame received