Python SDK

This article mainly introduces how to use the paho-mqtt client library in a Python project to achieve functions such as connecting, subscribing, unsubscribing, and sending/receiving messages between the client and MQTT server.

paho-mqtt is currently a widely used MQTT client library in Python. It provides support for MQTT v5.0, v3.1, and v3.1.1 for client classes on Python 2.7.9+ or 3.6+. It also provides some utility functions, making it very easy to publish messages to an MQTT server.

Prerequisites

Get Connection Parameters

After creating a usable device through WaveshareCloud in the Device|Attribute List, click the yellow button on the right: View Address to obtain relevant information.

Example:

MqttPath: mqtt.waveshare.cloud
Port: 1883
Client ID: 052405b2
Pub Topic: Pub/10/16/052405b2
Sub Topic: Sub/10/16/052405b2

Confirm Python Version

This project is tested with Python 3.10.9:

→ ~ python -V
Python 3.10.9

Install Paho-mqtt

pip is a Python package management tool, which provides the function of finding, downloading, installing and uninstalling Python packages. Use the following command to install paho-mqtt.

pip install paho-mqtt

Import Paho-mqtt

import paho.mqtt.client as mqtt

Connection Methods

Set MQTT connection address, port, topics, and client ID.

            HOST = "mqtt.waveshare.cloud"
            PORT = 1883
            Client_ID = "052405b2"  # Fill in the client id
            Publish_Topic = 'Pub/10/16/052405b2'  # Fill in the publishing topic
            Subscribe_Topic = 'Sub/10/16/052405b2'  # Fill in the subscribing topic
        

Set MQTTS connection address, port, topics, and client ID.
Load the CA certificate in the code by copying it locally.

            HOST = "mqtt.waveshare.cloud"
            PORT = 8883
            Client_ID = "052405b2"  # Fill in the client id
            Publish_Topic = 'Pub/10/16/052405b2'  # Fill in the publishing topic
            Subscribe_Topic = 'Sub/10/16/052405b2'  # Fill in the subscribing topic
            client = mqtt.Client(Client_ID)
            # SSL/TSL configuration
            client.tls_set(ca_certs=None, certfile=None, keyfile=None, cert_reqs=mqtt.ssl.CERT_NONE, tls_version=mqtt.ssl.PROTOCOL_TLS)
        

Set MQTTS connection address, port, topics, and client ID.
Load the CA certificate in the code by copying it locally.

            HOST = "mqtt.waveshare.cloud"
            PORT = 8884
            Client_ID = "052405b2"  # Fill in the client id
            Publish_Topic = 'Pub/10/16/052405b2'  # Fill in the publishing topic
            Subscribe_Topic = 'Sub/10/16/052405b2'  # Fill in the subscribing topic
            client = mqtt.Client(Client_ID)
            # SSL/TSL certificate configuration
            ca_cert = "./cert/rootCA.crt"  # Replace with your CA certificate path
            client_cert = "./cert/server.crt"  # Replace with your client certificate path
            client_key = "./cert/server.key"  # Replace with your client key path
            client.tls_set(ca_certs=ca_cert, certfile=client_cert, keyfile=client_key, cert_reqs=mqtt.ssl.CERT_REQUIRED, tls_version=mqtt.ssl.PROTOCOL_TLS)
        

Write a callback function on_connect. It will be called directly after the MQTT connection. In this function, you can use rc to determine whether the client connection is successful. When rc is 0, the connection is successful. At this point, call paho.mqtt.client.subscribe to subscribe to messages.

def on_connect(client, userdata, flags, rc):
    print("Connected with result code " + str(rc))
    if rc == 0:
        client.subscribe(Subscribe_Topic)

Subscription topics have been implemented in the previous section.

Unsubscribe

Unsubscribe by using the following code. Specify the topic to unsubscribe at this time.

def unsubscribe(client: mqtt_client):
    client.on_message = None
    client.unsubscribe(topic)

Publish Topic

Use a while loop to publish the content of the message body.

        while True:
            message = "Hello, MQTT!"
            client.publish(Publish_Topic, message)
            print("Published message: " + message)
            time.sleep(1)

Receive Messages

Specify that the client listens for message events through the following code. After receiving a message, execute the callback function to print the received message to the console.

def on_message(client, userdata, msg):
  print("Received message: " + msg.payload.decode())

Disconnect

def disconnect(client: mqtt_client):
    client.loop_stop()
    client.disconnect()

Complete code

Connect via a TCP port

import paho.mqtt.client as mqtt
import time

HOST = "mqtt.waveshare.cloud"
PORT = 1883
Client_ID = "" 
Publish_Topic = '' 
Subscribe_Topic = '' 

client = mqtt.Client(Client_ID)

def on_connect(client, userdata, flags, rc):
    print("Connected with result code " + str(rc))
    if rc == 0:
        client.subscribe(Subscribe_Topic)

def on_message(client, userdata, msg):
    print("Received message: " + msg.payload.decode())

def define():
    client.on_connect = on_connect
    client.on_message = on_message
    client.connect(HOST, PORT, 60)
    client.loop_start()

if __name__ == '__main__':
    define()
    try:
        while True:
            message = "Hello, MQTT!"
            client.publish(Publish_Topic, message)
            print("Published message: " + message)
            time.sleep(1)

    except KeyboardInterrupt:
        client.loop_stop()
        client.disconnect()
        print("MQTT client disconnected.")

Connect over SSL/TSL ports (certificateless)

import paho.mqtt.client as mqtt
import time

HOST = "mqtt.waveshare.cloud"
PORT = 8884  
Client_ID = "" 
Publish_Topic = ''  
Subscribe_Topic = '' 

client = mqtt.Client(Client_ID)


client.tls_set(ca_certs=None, certfile=None, keyfile=None, cert_reqs=mqtt.ssl.CERT_NONE, tls_version=mqtt.ssl.PROTOCOL_TLS)

connected = False
def on_connect(client, userdata, flags, rc):
    global connected
    print("Connected with result code " + str(rc))
    if rc == 0:
        client.subscribe(Subscribe_Topic)

        connected = True

def on_message(client, userdata, msg):
    print("Received message: " + msg.payload.decode())

def define():
    client.on_connect = on_connect
    client.on_message = on_message
    client.connect(HOST, PORT, 60)
    client.loop_start()

if __name__ == '__main__':
    define()
    while not connected:
        time.sleep(1)
    try:
        while True:
            message = "Hello, MQTT!"
            client.publish(Publish_Topic, message)
            print("Published message: " + message)
            time.sleep(1)

    except KeyboardInterrupt:
        client.loop_stop()
        client.disconnect()
        print("MQTT client disconnected.")

Connect via SSL/TSL port (with certificate)

import paho.mqtt.client as mqtt
import time

HOST = "mqtt.waveshare.cloud"
PORT = 8884
Client_ID = ""  
Publish_Topic = '' 
Subscribe_Topic = '' 

client = mqtt.Client(Client_ID)

ca_cert = "Path/cert/rootCA.crt" 
client_cert = "Path/cert/server.crt" 
client_key = "Path/cert/server.key" 

client.tls_set(ca_certs=ca_cert, certfile=client_cert, keyfile=client_key, cert_reqs=mqtt.ssl.CERT_REQUIRED, tls_version=mqtt.ssl.PROTOCOL_TLS)

connected = False
def on_connect(client, userdata, flags, rc):
    global connected
    print("Connected with result code " + str(rc))
    if rc == 0:
        client.subscribe(Subscribe_Topic)

        connected = True

def on_message(client, userdata, msg):
    print("Received message: " + msg.payload.decode())

def define():
    client.on_connect = on_connect
    client.on_message = on_message
    client.connect(HOST, PORT, 60)
    client.loop_start()

if __name__ == '__main__':
    define()
    while not connected:
        time.sleep(1)
    try:
        while True:
            message = "Hello, MQTT!"
            client.publish(Publish_Topic, message)
            print("Published message: " + message)
            time.sleep(1)

    except KeyboardInterrupt:
        client.loop_stop()
        client.disconnect()
        print("MQTT client disconnected.")

Last modified: 12 一月 2024