MQTT w Python

Instalacja biblioteki: pip install paho-mqtt

import random
from paho.mqtt import client as mqtt_client
 
broker = '127.0.0.1'
port = 1883
# generate client ID with pub prefix randomly
client_id = f'python-mqtt-{random.randint(0, 100)}'
# username = 'username'
# password = 'password'
 
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, return code %d\n", rc)
 
    client = mqtt_client.Client(client_id)
    # client.username_pw_set(username, password)
    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/topic')
    client.on_message = on_message

msg = f"message"
topic = 'topic/topic'
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}")

W pętli działania programu trzeba podtrzymywać połączenie MQTT:

Przykład 1:

client.loop_start()
 
while True:
   pass
 
client.loop_stop()

Przykład 2:

while True:
    rc = client.loop(timeout=1.0)
    if rc != 0:
        # need to handle error, possible reconnecting or stopping the application