How to stop python websocket connection after some seconds?

Question

I am trying to develop a short script that connects to a real-time stock data provider through a websocket API, gets some data, makes some calculations, stores the results in a database and stops.

EDIT: I need to keep the connection alive for a few seconds until I get all required data. Thus, breaking the connection after the first message is not an option.

The problem I am facing is how to stop the run_forever() connection.

This is what I have so far:

import websocket
import json

def on_open(ws):
    channel_data = {
        "action": "subscribe",
        "symbols": "ETH-USD,BTC-USD"
    }
    ws.send(json.dumps(channel_data))
    
def on_message(ws, message):
    # Do some stuff (store messages for a few seconds)
    print(message)
    
def on_close(ws):
    print("Close connection")
    
socket = "wss://ws.url"
ws = websocket.WebSocketApp(socket, on_open=on_open, on_message=on_message)
ws.run_forever()
ws.close()

# Once the connection is closed, continue with the program

I do not want to stay connected after the "Do some stuff" is executed, how can I force the connection close?

Your help is much appreciated.

"how can I force the connection close?" ... by calling ws.close() when "the "Do some stuff" is executed", perhaps? Am I missing something? — esqew
– esqew, Commented Feb 26, 2022 at 18:13
Sorry, I was not too clear. The API provides several messages (actually, stock prices) but I need to keep the connection alive until all requested stocks are provided. Thus, I can´t close the connection in the first message received. Is there any way to set a counter? or a timer? — juancar
– juancar, Commented Feb 26, 2022 at 18:21
Instantiate a global variable that keeps track of the messages you've received and bump it up each time against the symbols you requested. Once the lists match, invoke close(). — esqew
– esqew, Commented Feb 26, 2022 at 18:26
I have tried something similar. I declared global n n=0 at the beginning of on_open() function and n+=1 inside the on_message() function. But if I try to print(n) inside this function, it does not seem to do anything — juancar
– juancar, Commented Feb 26, 2022 at 18:35

juancar · Accepted Answer · 2022-02-26 18:56:23Z

I managed how to solve this. I leave my solution in case it is useful to someone.

I just added some attributes to the ws object that allows me to track the number of messages received and store them into a list to work with once the connection is closed.

import websocket
import json

def on_open(ws):
    channel_data = {
        "action": "subscribe",
        "symbols": "ETH-USD,BTC-USD"
    }
    ws.send(json.dumps(channel_data))
    
def on_message(ws, message):
    
    ws.messages_count+=1
    ws.messages_storage.append(message)
    
    if ws.messages_count>50:
        ws.close()
    
def on_close(ws):
    print("Close connection")
    
socket = "wss://ws.url"
ws = websocket.WebSocketApp(socket, on_open=on_open, on_message=on_message)

# Create a counter and an empty list to store messages
ws.messages_count = 0
ws.messages_storage = []

# Run connection
ws.run_forever()

# Close connection
ws.close()

# Continue with the program

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