Exploring Mqtt Protocol With Python In The Internet Of Things

The Internet of Things (IoT) is greatly dependent on seamless data communication. Choosing an appropriate communication protocol is crucial. MQTT (Message Queuing Telemetry Transport) is a popular choice among developers. It is a lightweight publish-subscribe network protocol designed for constrained devices and low-bandwidth, high-latency networks.

In this blog, we will dive into the basics of MQTT and how to implement it using Python.

What is MQTT?

MQTT stands for Message Queuing Telemetry Transport. It is an extremely simple messaging protocol designed for restricted devices working in unreliable networks. The MQTT protocol is based on the principle of publishing messages and subscribing to topics, or "publish/subscribe".

Basic components of MQTT

• Publisher: Publishes messages to the broker on a particular topic.
• Broker (Server): Intermediate server which takes messages from the publishers and sends those messages to the subscribers.
• Subscriber: Subscribes to certain topics and receives messages from the broker.

In Python, we use the Paho library to work with MQTT.

Setting Up MQTT Broker

To demonstrate MQTT in action, we can use a public broker. Eclipse provides a free MQTT broker for developers. We can connect to it using this address: mqtt.eclipse.org.

Installing Paho-MQTT Package

We require paho-mqtt package. We can install it using pip.

pip install paho-mqtt

Python Implementation: Publish a Message

We are going to create a simple publisher that sends a hello message to the topic 'iot_topic/test'.

import paho.mqtt.client as mqtt

def on_publish(client,userdata,result):  # create function for callback
    print("data published \n")
    pass

client= mqtt.Client()  # create class instance

client.on_publish = on_publish  # assign function to callback
client.connect("mqtt.eclipse.org")  # establish connection
ret= client.publish("iot_topic/test","Hello World!")  # publish

Here's how the code works:

• mqtt.Client() : Creates a MQTT client.
• client.on_publish : Sets the function to callback after the message is published.
• client.connect(BROKER_ADDRESS) : Connects to the broker.
• client.publish(TOPIC,message) : Publishes the message on the given topic.

This program will publish the message "Hello World!" to the topic 'iot_topic/test'.

From the simplicity of MQTT and Python, you can see why it's a favored combination in IoT development.

Remember, make sure any devices you're publishing and subscribing to agree on the topic names, the broker, and the broker's address.