Manage wireless hosted network in Windows 8 with netsh

Question

My script reads data from MQTT server and writes it to postgres table.
I'm using loop_forever(). The program is supposed to run nonstop.

When the first connection is received everything works fine, but after some time (from minutes to days) on_connect() is called again. The program works (in the meaning that there is no error in connection) but no meassages are received any more.

In order to debug I tried following:

• induce disconnect by switching off and on the network connection
• shutting off and on the server
• calling client.disconnect()

To my surprise first and second thing did nothing - there was no logs about new connection and the running program just kept running after the connection revived.
The third attempt was unsuccesfull, I couldn't make it work.

Other remarks:

• I tried using loop_start() instead of loop_forever but was not succesfull with that at all

So basically the questions are:

• how to counter-act ?
• how to disconnect manually to replicate the problem of calling on_connect (and loosing incoming data)

My code:

import json
import sys
from paho.mqtt import client as mqtt_client
import psycopg2
import logging as log
from datetime import datetime
import certifi
from collections import defaultdict


def connect_mqtt(userdict) -> mqtt_client:
    def on_connect(client, userdata, flags, rc):
        log.info(f"{datetime.now()}: Trying connect")
        if rc == 0:
            log.info(f"{datetime.now()}: Connection returned result: " + mqtt_client.connack_string(rc))
        else:
            log.info("Failed to connect, return code %d\n", rc)

    client = mqtt_client.Client(client_id=conf['client_id'], protocol=mqtt_client.MQTTv31, userdata=userdict)
    client.tls_set(certifi.where())
    client.tls_insecure_set(True)

    client.username_pw_set(conf['username'], conf['password'])
    client.on_connect = on_connect
    client.connect(conf['broker'], conf['port'])
    return client


def on_message(client, userdata, msg):
    now_ts_in_s = round(datetime.timestamp(datetime.now()))
    now_dt_in_s = datetime.fromtimestamp(now_ts_in_s)

    try:
        value = float(msg.payload.decode())
        data = [now_dt_in_s,  value]
        insert_to_psql(userdata['conn'], data)
    except ValueError:
        pass


def insert_to_psql(conn, data):
    cursor = conn.cursor()
    insert_query = "INSERT INTO data (time, value) VALUES (%s, %s) ON CONFLICT " \
                   "DO " \
                   "NOTHING;"
    cursor.execute(insert_query, data)
    conn.commit()


def run():
    psql_conn = "postgres://postgres:blablabla"
    conn = psycopg2.connect(psql_conn)

    userdict = {'collected_data': defaultdict(list), 'conn': conn, 'first_conn': True}
    client = connect_mqtt(userdict)
    client.subscribe(conf['topic'])
    client.on_message = on_message
    try:
        client.loop_forever()
    finally:
        client.disconnect()
        conn.close()


if __name__ == '__main__':
    with open(sys.argv[1]) as f:
        conf = json.load(f)
    run()

Solution

The key of the hosted network can be changed using this command:

netsh wlan set hostednetwork key=yourkey keyusage=temporary|persistent

See Netsh Commands for Wireless Local Area Network (WLAN) in Windows Server 2008 R2.

Comments

[Loren_]

Hi, and welcome to Super User! Add your solution as an answer, and mark it as accepted!

[Daniel R]

" That's why subscriptions should be made in the on_connect callback." Thank I'll try that, seems to be solution. On the second part - I have shut down the server, and then turned it on, the running script did not seem to received new on_connect()

[Daniel R]

"Apart from that, messages won't be lost if you configure your broker accordingly. MQTT has various QOS settings for that specific purpose." But that rquires configuring server, right? I don't think I have permission to that (it's not mine), but will check it out

[The Fool]

If you are not in control, you can't do much about it, I guess. If your app isn't connected, it isn't connected. Network issues can't be 100% prevented. It's an involuntary disruption. Potentially you can use a subscription group and deploy your app multiple times, if you think your code is the issue and not something from the outside.