mqtt-pub-java

This demo application is written in Java using the Gradle build system. It publishes mock sensor readings to an MQTT broker.

New: YAML-driven generic sensors

• Sensors are now configured via YAML. A single generic sensor class generates values between min/max with a given step.
• RoomReport now contains a dynamic map of sensor label -> value.
• MQTT clientId, broker address, topic, and publish interval are configurable.

Configuration

Provide configuration via one of these environment variables:

• APP_CONFIG: the YAML contents directly.
• APP_CONFIG_PATH: a file path to a YAML file.

Example YAML (see app/bin/sample-config.yaml):

mqtt:
  addr: "tcp://broker:1883"
  clientId: "room-sensor-1"
  topic: "sensors/room"
  intervalMs: 1000
sensors:
  - label: "temperature"
    min: 15.0
    max: 35.0
    step: 0.5
    initial: 25.0
    integer: false
  - label: "co2Level"
    min: 450
    max: 1200
    step: 50
    initial: 600
    integer: true

Build and Run

• Build: ./gradlew :app:build
• Run (using a file):
  • export APP_CONFIG_PATH=$(pwd)/app/bin/sample-config.yaml
  • ./gradlew :app:run
• Or run (inline):
  • export APP_CONFIG="$(cat app/bin/sample-config.yaml)"
  • ./gradlew :app:run

The app will connect to mqtt.addr, publish JSON to mqtt.topic every mqtt.intervalMs milliseconds, and identify as mqtt.clientId.