^{Lorenzo Mirto Bertoldo @climadd}

IoT Gateway

Quickstart Guide

The gateway process involves four main classes that must be executed in the following order:

1. BackendMessageReceiver.java – iotGateway.src.test.java.org.lore.mqtt.backend
2. GatewayApp.java – iotGateway.src.main.java.org.lore.app
3. SimulatorGUIApp.java – iotGateway.src.test.java.org.lore.mqtt.backend.simulators
4. BackendMessageSender.java – iotGateway.src.test.java.org.lore.mqtt.backend

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Project Overview

• The Gateway acts as a bridge between the Broker and the IoT Devices (Sensors and Actuators). It communicates with the Backend via the MQTT protocol and uses dynamically allocated TCP sockets to establish communication with the IoT Devices.

• The Simulated Sensors generate realistic fluctuations in their measured values. As displayed in the GUI, sensors independently produce a stream of data, which is sent via TCP Socket to the Gateway. The gateway encapsulates this data into MQTT-formatted Queries for the Backend. This data retrieval process can either be scheduled by a backend script or triggered manually by user requests.

• The Simulated Actuators mimic real IoT actuators that toggle between different modes. They store multiple boolean or enumeration values, which can be modified by gateway-issued queries through their dedicated TCP socket. The GUI displays the real-time status of all actuator variables.

• The Simulated Backend consists of two classes:

  • BackendMessageSender – Handles sending messages through the MQTT Broker.
  • BackendMessageReceiver – Receives and prints incoming messages in the terminal.

• The Messages follow the MQTT format, and all enumeration-type data related to both messages and measurements is cataloged in the main.java.org.lore.models.mqtt package.

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MQTT Message Topics and Format

Query Topics

• Request for sensor temperature data

  • Topic: azienda{idAzienda}/serra{idSerra}/sensori/temperatura/rx
  • Example: 3/5/sensori/temperatura/rx

• Request for actuator state or status change

  • Topic: azienda{idAzienda}/serra{idSerra}/attuatori/illuminazione/rx
  • Example: 3/5/attuatori/illuminazione/rx

Response Topics

• Sensor temperature response

  • Topic: azienda{idAzienda}/serra{idSerra}/sensori/temperatura/sx
  • Example: 3/5/sensori/temperatura/sx

• Actuator state response

  • Topic: azienda{idAzienda}/serra{idSerra}/attuatori/illuminazione/sx
  • Example: 3/5/attuatori/illuminazione/sx

Message Format

Sensor Request Message

{
  "type": "read",
  "device": "sensori"
}

Actuator State Change Request Message

{
  "type": "write",
  "device": "attuatori",
  "state": "on/off",
  "level": "low/medium/high",
  "mode": "auto/manual"
}

Actuator Status Request Message

{
  "type": "read",
  "device": "attuatori"
}

RESPONSE MESSAGES:

Sensor Data Response

{
  "type": "read",
  "device": "sensori",
  "value": float		//Exclusive to sensor device
}

Actuator State Change Response

{
  "type": "write",
  "device": "attuatori",
  "state": "on/off",
  "level": "low/medium/high",
  "mode": "auto/manual",
  "result": boolean		//Exclusive to sensor (true = operation successful)
}

Structural Analysis

GatewayApp

• Function: Receives MQTT messages and forwards them via TCP sockets to the appropriate IoT devices.
• Response Handling: Creates a response object upon receiving a message and sends it to the backend.

Scalability

• Initial Specification: Assumes a fixed number of sensor-actuator pairs (Temperature, Humidity, Lighting).
• Future Expansion: Uses hashmaps for dynamic TCP socket initialization, allowing support for additional devices.

MQTT Processing

• Listener Class: GWBEListener
• Subscription: Registers a listener using the .subscribe() method.
• Message Handling:
  • Trigger: The .messageArrived() method is invoked upon message reception.
  • Processing: Extracts topic fields and parses the JSON payload to determine the necessary actions.

BackendMessageSender

• Purpose: Simulates backend requests.
• Logging: Prints all sent messages to the terminal.
• Connection Management: Performs .disconnect() and .close() once all messages are sent.

BackendMessageReceiver

• Purpose: Simulates the backend receiving MQTT messages.
• Logging: Prints all received messages to the terminal.
• Subscription: Uses .subscribe() to listen to the appropriate topic, utilizing DummyListener.java, an interface extending IMqttMessageListener.

SimulatorGUIApp

• Function: Provides a graphical interface to monitor sensor measurements and actuator states.
• Sensor Values:
  • Initialized to 0
  • Updated every 30 seconds using .getRandomByRange() from RandomUtils
• Actuator States: Variables like State, Level, and Mode are defined as enums in main.java.org.lore.models.mqtt.
• GUI Refresh:
  • Refreshes every 2 seconds via .refreshGUI()
  • Displays actuator state updates in response to MQTT "write" messages.

TCP Servers for Simulated Devices

• Thread Management: GUI contains 6 threads (one per device type), each running a dedicated TCP server.
• Logging: Prints messages to the terminal when a TCP connection is successfully established.
• Device Logic:
  • Implemented in test.java.org.lore.tcp within the classes TempTCPServer, UmiTCPServer, and IllTCPServer.
  • Each class invokes .getRandomByRange() to generate sensor values.
  • The .compute() method processes incoming MQTT messages, executing the corresponding logic based on message type (READ or WRITE).