Spring Boot MQTT

🍃Spring Boot Projects mqtt

Introduction

By the time you’re reading this article, the application only contains an unauthenticated MQTT publisher.

I planned to write a more complete application with authentication, subscriber and more robust settings page.

MQTT broker setup for Windows

Since I wrote this code within a Windows machine, here is a short slice where I show you how to setup both an MQTT broker and an MQTT subscriber to debug the application.

First of all, install the right executable file from mosquitto.org/download page:

• mosquitto-2.0.22-install-windows-x64.exe or,
• mosquitto-2.0.22-install-windows-x86.exe.

Running the executable will create the following directory: C:\Program Files\mosquitto.

Open mosquitto.conf file and paste the following configuration:

# Config file for mosquitto
allow_anonymous true

# listener port-number [ip address/host name/unix socket path]
listener 1883

Within C:\Program Files\mosquitto directory, open a couple of Command Prompt windows with Administrator rights.

The first one will run the broker:

MQTT broker

.\mosquitto.exe -c "C:\Program Files\mosquitto\mosquitto.conf" -v

The second one will subscribe to events topic:

MQTT subscriber

.\mosquitto_sub.exe -p 1883 -h localhost -t events

You can now run the Spring Boot application and trigger some events using the POST API.

Code Structure

• Directorysrc/main

  • Directoryjava/com/pietropoluzzi/mqtt

    • Directorycontroller

      • EventController.java Expose POST API to trigger MQTT publish
    • Directorymodel

      • Event.java model for both HTTP POST and MQTT payload
    • Directoryservice

      • EventService.java instantiated by the controller, calls MqttPublisherService
      • MqttPublisherService.java publish MQTT message with payload from EventService
    • Directoryutil/ holds custom Swagger annotations

      • …
  • Directoryresources

    • application.properties
• pom.xml

API

With the application running, you can take a look at swagger API definition.

Swagger UI Take a look at API definition

Here is a screenshot from Postman: