一、介绍

MQTT（Message Queuing Telemetry Transport，消息队列遥测传输协议），是一种基于发布/订阅（publish/subscribe）模式的“轻量级”通讯协议，该协议构建于TCP/IP协议上。
MQTT可以用极少的代码和有限的带宽，为连接远程设备提供实时可靠的消息服务。
作为一种低开销、低带宽占用的即时通讯协议，使其在物联网、小型设备、移动应用等方面有较广泛的应用。

二、代码实现

import ssl
import json

import paho.mqtt.client as mqtt

# The callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, flags, reason_code, properties):
    print(f"Connected with result code {reason_code}")
    # Subscribing in on_connect() means that if we lose the connection and
    # reconnect then subscriptions will be renewed.
    client.publish("xxx/xx", json.dumps({}))
    client.subscribe("xxx/xx")



# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
    print(msg.topic+" "+str(msg.payload))

# 忽略证书
mqttc = mqtt.Client(mqtt.CallbackAPIVersion.VERSION2)
mqttc.username_pw_set("username", "password")
mqttc.tls_set(cert_reqs=ssl.CERT_NONE)
mqttc.on_connect = on_connect
mqttc.on_message = on_message

mqttc.connect("a.com", 8883, 60)

# Blocking call that processes network traffic, dispatches callbacks and
# handles reconnecting.
# Other loop*() functions are available that give a threaded interface and a
# manual interface.
mqttc.loop_forever()