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)

Understanding blocking and non-blocking code

So far, we have been working with blocking calls that processed MQTT-related network traffic and dispatched callbacks. Whenever we called the client.loop method in the previous examples, the method used the default values for the two optional arguments: 1 for timeout and 1 for max_packets. The method blocks for up to one second, that is, the value of the timeout argument, to handle incoming or outgoing data. The method runs with a synchronous execution, and therefore, the next line of code won't be executed until this method returns. We called the client.loop method in the main thread, and therefore, no other code can be executed in this thread while the client.loop method is blocking.

In our first example with Python code that created an MQTT client, we called the client.loop_forever method. This method blocks until the client...