Book Image

Hands-On MQTT Programming with Python

By : Gaston C. Hillar
Book Image

Hands-On MQTT Programming with Python

By: Gaston C. Hillar

Overview of this book

<p>MQTT is a lightweight messaging protocol for small sensors and mobile devices. This book explores the features of the latest versions of MQTT for IoT and M2M communications, how to use them with Python 3, and allow you to interact with sensors and actuators using Python.</p> <p>The book begins with the specific vocabulary of MQTT and its working modes, followed by installing a Mosquitto MQTT broker. You will use different utilities and diagrams to understand the most important concepts related to MQTT. You will learn to make all the necessary configuration to work with digital certificates for encrypting all data sent between the MQTT clients and the server. You will also work with the different Quality of Service levels and later analyze and compare their overheads.</p> <p>You will write Python 3.x code to control a vehicle with MQTT messages delivered through encrypted connections (TLS 1.2), and learn how leverage your knowledge of the MQTT protocol to build a solution based on requirements. Towards the end, you will write Python code to use the PubNub cloud-based real-time MQTT provider to monitor a surfing competition.</p> <p>In the end, you will have a solution that was built from scratch by analyzing the requirements and then write Python code that will run on water-proof IoT boards connected to multiple sensors in surfboards.</p>
Table of Contents (9 chapters)

Receiving messages in Python

We will use the recently installed paho-mqtt version 1.3.1 module to subscribe to a specific topic and run code when we receive messages in the topic. We will create a VehicleCommandProcessor class in the same Python file, named vehicle_mqtt_client.py, in the main virtual environment folder. This class will represent a command processor associated to an instance of the previously coded Vehicle class, configure the MQTT client and the subscription to the client, and declare the code for the callbacks that are going to be executed when certain events related to MQTT are fired.

We will split the code for the VehicleCommandProcessor class into many code snippets to make it easier to understand each code section. You have to add the next lines to the existing vehicle_mqtt_client.py Python file. The following lines declare the VehicleCommandProcessor class...