Book Image

MQTT Essentials - A Lightweight IoT Protocol

5 (1)
Book Image

MQTT Essentials - A Lightweight IoT Protocol

5 (1)

Overview of this book

This step-by-step guide will help you gain a deep understanding of the lightweight MQTT protocol. We’ll begin with the specific vocabulary of MQTT and its working modes, followed by installing a Mosquitto MQTT broker. Then, you will use best practices to secure the MQTT Mosquitto broker to ensure that only authorized clients are able to publish and receive messages. Once you have secured the broker with the appropriate configuration, you will develop a solution that controls a drone with Python. Further on, you will use Python on a Raspberry Pi 3 board to process commands and Python on Intel Boards (Joule, Edison and Galileo). You will then connect to the MQTT broker, subscribe to topics, send messages, and receive messages in Python. You will also develop a solution that interacts with sensors in Java by working with MQTT messages. Moving forward, you will work with an asynchronous API with callbacks to make the sensors interact with MQTT messages. Following the same process, you will develop an iOS app with Swift 3, build a website that uses WebSockets to connect to the MQTT broker, and control home automation devices with HTML5, JavaScript code, Node.js and MQTT messages
Table of Contents (16 chapters)
MQTT Essentials - A Lightweight IoT Protocol
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Testing WebSockets with the Eclipse Paho client JavaScript utility

We will use the Eclipse Paho client JavaScript utility to generate a simple MQTT over WebSockets client on a web browser. We will make this client subscribe to a topic and print all the messages it receives. Follow the next steps:

  1. Open a web browser in the same computer in which you are running the Mosquitto server and navigate to http://www.ecli .

  2. Enter localhost in Host.

  3.  Enter 9001 in Port.

  4. Make sure /ws is specified in Path.

  5. Make sure the TLS checkbox is unchecked. The following screenshot shows the web page with the appropriate values for the connection options:

  6. Click Connect. The web page will display Connected to: localhost:9001/ws as, followed by the Client ID that was automatically generated.

  7. Go to the Subscribe panel. Enter home/control/leds/1 in Topic, below Subscribe.

  8. Select 2 in the QoS dropdown below Subscribe. The following screenshot shows the Subscribe panel with the appropriate...