5-python library-paho mqtt communication

mqtt can be said to show a very widely used protocol on the Internet of Things, its light weight, simple, open and easy to implement these characteristics. Paho also implemented the python version of mqtt.

1. Connect

Connect and call the connect interface, then call loop_forever and start running

The third parameter of connect is the heartbeat time of mqtt

on_connectAnd on_disconnecta callback function for successful connection and disconnection,

import paho.mqtt.client as mqtt

mqttClient = mqtt.Client("python_test")


def on_disconnect(client, userdata, rc):
    print("mqtt broker lost "+str(rc))


def on_connect(client, userdata, flags, rc):
    print("Connected with result code " + str(rc))


if __name__ == '__main__':
    mqttClient.on_connect = on_connect
    mqttClient.on_disconnect = on_disconnect
    mqttClient.connect("192.168.18.1", 1883, 10)
    mqttClient.loop_forever()
    

2. SSL login

To add a certificate, just add the following two before calling the connect function.

mqttClient.tls_set(ca_certs="cacert.pem", certfile=None, keyfile=None, cert_reqs=mqtt.ssl.CERT_REQUIRED,
                       tls_version=mqtt.ssl.PROTOCOL_TLSv1, ciphers=None)
    mqttClient.tls_insecure_set(True)

3. Account password

To set the account password, add the following item before calling the connect function.

mqttClient.username_pw_set("python", passwd)

4.WILL theme settings

Set the WILL theme, before calling the connect function, use the will_set interface to set, add will theme and will theme payload

will_payload = {
    "ver":  "v1",
    "module": "offline",
    "api":  "disconnect",
    "param":  [{
        "k": "mac",
        "v": "DC4BDD1DFA48"
    }, {
        "k": "protypeid",
        "v": "PYTHON"
    }]
}
    
mqttClient.will_set("local/offline", payload=json.dumps(will_payload), qos=CLINET_TOPIC_QOS)

5. Subscribe

The subscription of the topic uses the subscribe interface, which is generally set in the on_connect callback function

After subscribing to the topic, our purpose is to receive the subscribed data, so we need to set the callback function on_message to receive data
, as long as there is data sent over on_message will receive.

#!/usr/bin/python3
# -*- coding:utf-8 -*-
# Author: ye.lin
# Time: 2020/02/24
# Describe：

import paho.mqtt.client as mqtt

mqttClient = mqtt.Client("python_test")

def on_disconnect(client, userdata, rc):
    print("mqtt broker lost "+str(rc))


def on_connect(client, userdata, flags, rc):
    print("Connected with result code " + str(rc))
    mqttClient.subscribe(local/broadcast, qos=1)


def on_message_come(lient, userdata, msg):
    print(msg.topic + " " + ":" + str(msg.payload))


if __name__ == '__main__':
    mqttClient.on_connect = on_connect
    mqttClient.on_disconnect = on_disconnect
    mqttClient.on_message = on_message_come

    mqttClient.tls_set(ca_certs="zgateway_cacert.pem", certfile=None, keyfile=None, cert_reqs=mqtt.ssl.CERT_REQUIRED,
                       tls_version=mqtt.ssl.PROTOCOL_TLSv1, ciphers=None)
    mqttClient.tls_insecure_set(True)

    mqttClient.connect("192.168.18.1", 6885, 10)
    mqttClient.loop_forever()

6. Release

Publish using the publish interface, as follows

    info_payload = {
        "msg":      "test"
    }
    mqttClient.publish("local/notify", payload=json.dumps(info_payload), qos=CLINET_TOPIC_QOS)