Paho MQTT with Python

Pradeep Singh | 29th March 2016

Prerequisites:

Computer with Python 2.7 and working internet connection.

Client Installation:

Install Paho MQTT Client on your machine using pip command –

pip install paho-mqtt

Once the client is installed you write the code for Publisher and Subscriber using Python. Here in this example I am going to use Python 2.7 –

MQTT Subscribe:

Following code will subscribe our client to”helloTopic” (GitHub Link for Code File) –

# Import package
import paho.mqtt.client as mqtt

# Define Variables
MQTT_HOST = "iot.eclipse.org"
MQTT_PORT = 1883
MQTT_KEEPALIVE_INTERVAL = 45
MQTT_TOPIC = "helloTopic"
MQTT_MSG = "hello MQTT"

# Define on connect event function
# We shall subscribe to our Topic in this function
def on_connect(mosq, obj, rc):
 mqttc.subscribe(MQTT_TOPIC, 0)

# Define on_message event function. 
# This function will be invoked every time,
# a new message arrives for the subscribed topic 
def on_message(mosq, obj, msg):
 print "Topic: " + str(msg.topic)
 print "QoS: " + str(msg.qos)
 print "Payload: " + str(msg.payload)

def on_subscribe(mosq, obj, mid, granted_qos):
 print("Subscribed to Topic: " + 
 MQTT_MSG + " with QoS: " + str(granted_qos))

# Initiate MQTT Client
mqttc = mqtt.Client()

# Assign event callbacks
mqttc.on_message = on_message
mqttc.on_connect = on_connect
mqttc.on_subscribe = on_subscribe

# Connect with MQTT Broker
mqttc.connect(MQTT_HOST, MQTT_PORT, MQTT_KEEPALIVE_INTERVAL)

# Continue monitoring the incoming messages for subscribed topic
mqttc.loop_forever()

MQTT Publish:

Following code will register with MQTT Server and Publish Message to “helloTopic” (GitHub Link for Code File)-

# Import package
import paho.mqtt.client as mqtt

# Define Variables
MQTT_HOST = "iot.eclipse.org"
MQTT_PORT = 1883
MQTT_KEEPALIVE_INTERVAL = 45
MQTT_TOPIC = "helloTopic"
MQTT_MSG = "hello MQTT"

# Define on_publish event function
def on_publish(client, userdata, mid):
 print "Message Published..."

# Initiate MQTT Client
mqttc = mqtt.Client()

# Register publish callback function
mqttc.on_publish = on_publish

# Connect with MQTT Broker
mqttc.connect(MQTT_HOST, MQTT_PORT, MQTT_KEEPALIVE_INTERVAL) 

# Publish message to MQTT Broker 
mqttc.publish(MQTT_TOPIC,MQTT_MSG)

# Disconnect from MQTT_Broker
mqttc.disconnect()

Result:

Execute the Subscriber followed by Publisher code in two different terminals. After successful execution you should be able to see “hello MQTT” message in the terminal where you ran Subscriber code.

Subscribed to Topic: hello MQTT with QoS: (0,)
Topic: helloTopic
QoS: 0
Payload: hello MQTT