Nataliya Lisjo, student ECUtbildning Software developer in Industrial IoT, december 2020

<h2>============================</h2>

# Mosquitto MQTT protocol -- computer is your MQTT Broker

-download "mosquitto-1.6.10a-install-windows-x64"
-go to "cmd" in your PC -> runs as administrator
-write "net start mosquitto" --> now, your comp is BROKER MQTT-->
-to stop "net stop mosquitto"

<h2>VS code & paho-mqtt 1.5.1</h2>

go to https://pypi.org/project/paho-mqtt/ copy string "pip install paho-mqtt" and paste in VSCode -> new terminal . This file will be installed by itself in your VScode editor
Type in terminal : "pip list" -->
you can see the list of installed libraries to controll
<h2> Create MQTT folder </h2>

with 2 files which you can find bellow "**CODE**":
pub.py ---- publish
sub.py --------subscribe

<h2> Start run MQTT protocol </h2>

Open 2 windows in Windows PowerShell in right folder MQQT


Type "ls" (l~~i~~s~~t~~),then you can see ,if everythings see each other


in 1 windows type "python .\pub.py" --- Enter
in 2 windows type "python .\sub.py" --- Enter
now it should send message and ???
____________
got mistake somewhere

now everythings work
it was mistake in topic name in file pub.py . different topics name in files sub.py and pub.py in code.


good luck...

# Code

Save those 2 file in MQQT folder separate
pub.py ---- publish

import random
import time

from paho.mqtt import client as mqtt_client

broker = 'localhost'
port = 1883
topic = "/python/mqtt"

client_id = f'python-mqtt-{random.randint(0,1000)}'

def connect_mqtt():
    def on_connect(client, userdata, flags ,rc):
        if rc == 0:
            print("Connected to MQTT Broker!")
        else:
            print("Failed to connect")
            
    client = mqtt_client.Client(client_id)
    client.on_connect = on_connect
    client.connect(broker,port)
    return client

def publish(client):
    msg_count = 0
    while True:
        time.sleep(1)
        msg = f"message: {msg_count}"
        result = client.publish(topic, msg)
        
        status = result[0]
        if status == 0:
            print(f" Send '{msg}' to topic '{topic}'")
        else:
             print(f" Failed to send message to topic: '{topic}'")
        msg_count += 1
        
def run():
    client = connect_mqtt()
    client.loop_start()
    publish(client)
    
if __name__ == '__main__':
    run()

sub.py --------subscribe

import random
from paho.mqtt import client as mqtt_client

broker = "localhost"
port = 1883
topic = "/python/mqtt"

client_id = f'python-mqtt-{random.randint(0,1000)}'

def connect_mqtt() -> mqtt_client:
    def on_connect(client, userdata, flags, rc):
        if rc == 0:
            print("Connected to MQTT Broker")
        else:
            print("Failed to connect!")
        
    client = mqtt_client.Client(client_id)
    client.on_connect = on_connect
    client.connect(broker,port)
    return client

def subscribe(client:mqtt_client):
    def on_message(client, userdata, msg):
        print(f"Received '{msg.payload.decode()}' from '{msg.topic}' topic")
        
    client.subscribe(topic)
    client.on_message = on_message
        
        
def run():
    client = connect_mqtt()
    subscribe(client)
    client.loop_forever()
    
if __name__ == '__main__':
    run()

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