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Hands-On MQTT Programming with Python

Hands-On MQTT Programming with Python

By : Gaston C. Hillar
2.3 (3)
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Hands-On MQTT Programming with Python

Hands-On MQTT Programming with Python

2.3 (3)
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)
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Preface
Preface
Who this book is for
What this book covers
To get the most out of this book
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1
Installing an MQTT 3.1.1 Mosquitto Server
Installing an MQTT 3.1.1 Mosquitto Server
Understanding convenient scenarios for the MQTT protocol
Working with the publish-subscribe pattern
Working with message filtering
Understanding the MQTT puzzle – clients, servers, and connections
Installing a Mosquitto server on Linux
Installing a Mosquitto server on macOS
Installing a Mosquitto server on Windows
Considerations for running a Mosquitto server in the cloud
Test your knowledge
Summary
2
Using Command-Line and GUI Tools to Learn How MQTT Works
Using Command-Line and GUI Tools to Learn How MQTT Works
Subscribing to topics with a command-line tool
Subscribing to topics with a GUI tool
Publishing messages with a command-line tool
Publishing messages with a GUI tool
Unsubscribing from topics with a GUI tool
Learning best practices for topics
Understanding MQTT wildcards
Learning about the different QoS levels
Working with at least once delivery (QoS level 1)
Working with exactly once delivery (QoS level 2)
Understanding overhead in the different Quality of Service levels
Test your knowledge
Summary
3
Securing an MQTT 3.1.1 Mosquitto Server
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Securing an MQTT 3.1.1 Mosquitto Server
Understanding the importance of securing a Mosquitto server
Generating a private certificate authority to use TLS with Mosquitto
Creating a certificate for the Mosquitto server
Configuring TLS transport security in Mosquitto
Testing the MQTT TLS configuration with command-line tools
Testing the MQTT TLS configuration with GUI tools
Creating a certificate for each MQTT client
Configuring TLS client certificate authentication in Mosquitto
Testing the MQTT TLS client authentication with command-line tools
Testing the MQTT TLS configuration with GUI tools
Forcing the TLS protocol version to a specific number
Test your knowledge
Summary
4
Writing Code to Control a Vehicle with Python and MQTT Messages
Writing Code to Control a Vehicle with Python and MQTT Messages
Understanding the requirements to control a vehicle with MQTT
Defining the topics and commands
Creating a virtual environment with Python 3.6.x and PEP 405
Understanding the directory structure for a virtual environment
Activating the virtual environment
Deactivating the virtual environment
Installing paho-mqtt for Python
Connecting a client to the secured MQTT server with paho-mqtt
Understanding callbacks
Subscribing to topics with Python
Configuring certificates for IoT boards that will work as clients
Creating a class to represent a vehicle
Receiving messages in Python
Working with multiple calls to the loop method
Test your knowledge
Summary
5
Testing and Improving Our Vehicle Control Solution in Python
Testing and Improving Our Vehicle Control Solution in Python
Processing commands with Python
Sending messages with Python
Working with the network loop with Python
Working with last will and testament with Python
Working with retained last will messages
Understanding blocking and non-blocking code
Using the threaded client interface
Test your knowledge
Summary
6
Monitoring a Surfing Competition with Cloud-Based Real-Time MQTT Providers and Python
Monitoring a Surfing Competition with Cloud-Based Real-Time MQTT Providers and Python
Understanding the requirements
Defining the topics and payloads
Coding a surfboard sensor emulator
Configuring the PubNub MQTT interface
Publishing data retrieved from sensors to the cloud-based MQTT server
Working with multiple MQTT servers
Running multiple clients
Building a web-based dashboard with freeboard
Test your knowledge
Summary
7
Solutions
Solutions
Chapter 1: Installing an MQTT 3.1.1 Mosquitto server
Chapter 2: Using Command-Line and GUI Tools to Learn How MQTT Works
Chapter 3: Securing an MQTT 3.1.1 Mosquitto Server
Chapter 4: Writing Code to Control a Vehicle with Python and MQTT Messages
Chapter 5: Testing and Improving our Vehicle Control Solution in Python
Chapter 6: Monitoring a Surfing Competition with Cloud-Based Real-Time MQTT Providers and Python
8
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Testing the MQTT TLS configuration with command-line tools

We will use the mosquitto_sub command-line utility included in Mosquitto to try to generate a simple MQTT client that subscribes to a topic and prints all the messages it receives. We will use the default configuration, to try to establish a communication with the Mosquitto server, by using the default 1883 port without a certificate authority certificate specified. Open a Terminal in macOS or Linux, or a Command Prompt in Windows, go to the directory in which Mosquitto is installed, and run the following command:

mosquitto_sub -V mqttv311 -t sensors/octocopter01/altitude -d

The mosquitto_sub utility will display the following error. The Mosquitto server is not accepting any connections on port 1883 anymore. Notice that the error message might be different depending on the platform:

Error: No connection could be made because...
End of Section 6
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