DESM — Distributed Energy System Management

A distributed system simulating a peer-to-peer network of thermal power plants competing to fulfill renewable energy requests. Plants self-organize into a token-ring network, run election algorithms to bid on energy requests, and report CO2 pollution data — all communicating via gRPC, MQTT, and REST.

Project Requirements

The full project specification is available in DPS_Project_2025.pdf.

Architecture

                    ┌──────────────────────────────┐
                    │  Renewable Energy Provider   │  Publishes energy requests every 10s
                    │  (MQTT → energy/requests/*)  │
                    └──────────────┬───────────────┘
                                   │
                                   ▼
┌──────────────────────────────────────────────────────────────┐
│                     MQTT Broker (Mosquitto)                  │
└──────┬─────────────────────────────────────────────────┬─────┘
       │ subscribe                                       │
       ▼                                                 ▼
┌─────────────┐  gRPC ring  ┌─────────────┐  gRPC ring  ┌─────────────┐
│ Power Plant │◄───────────►│ Power Plant │◄───────────►│ Power Plant │
│ (port 9001) │             │ (port 9002) │             │ (port 9003) │
└──────┬──────┘             └──────┬──────┘             └──────┬──────┘
       │ MQTT publish              │                           │
       │ pollution/data            │                           │
       ▼                           ▼                           ▼
    ┌──────────────────────────────────────────────────────────────┐
    │              Administration Server (:8080)                   │
    │          Spring Boot REST API + MQTT subscriber              │
    └──────────────────────────────┬───────────────────────────────┘
                                   │ REST
                                   ▼
                          ┌─────────────────┐
                          │ Administration  │
                          │     Client      │
                          │   (CLI menu)    │
                          └─────────────────┘

Components

Component	Description
Power Plant	Standalone process forming a self-organizing ring network. Competes in token-ring elections to supply energy. Simulates CO2 pollution sensing.
Renewable Energy Provider	Publishes energy purchase requests (5000–15000 kWh) via MQTT every 10 seconds.
Administration Server	Spring Boot app exposing REST endpoints for plant registration and CO2 pollution statistics. Subscribes to MQTT for live pollution data.
Administration Client	CLI tool for querying registered plants and pollution statistics.

How It Works

1. Energy requests are published by the provider to MQTT topics energy/requests/{id}.
2. All power plants subscribe to these topics. When a request arrives, it triggers a token-ring election via gRPC.
3. Each plant generates a random bid price. The election message circulates the ring — the lowest bid wins.
4. The winning plant "produces" energy (simulated delay) and the request is cleared.
5. Each plant runs a Gaussian CO2 sensor (sliding window of 8 readings), publishing aggregated pollution data to MQTT topic pollution/data.
6. The Administration Server collects pollution data and serves it through a REST API.

Technologies

Technology	Purpose
Java 21	Core language
Spring Boot 3.2.5	Administration server REST API
gRPC 1.72.0	Inter-plant ring network communication
Protocol Buffers 4.31.0	Serialization for gRPC messages
Eclipse Paho MQTT 1.2.5	Publish/subscribe for energy requests and pollution data
Mosquitto	MQTT broker (external dependency)
Gradle	Build system with protobuf plugin
JUnit 5	Testing

Prerequisites

• Java JDK 21+
• Mosquitto MQTT broker running on localhost:1883

Install Mosquitto:

sudo apt-add-repository ppa:mosquitto-dev/mosquitto-ppa
sudo apt-get update
sudo apt-get install mosquitto mosquitto-clients -y
mosquitto -d

Build

./gradlew build

Run

Start each component in a separate terminal.

1. Administration Server

./gradlew run --args='administration.AdministrationServer'

Runs on port 8080.

2. Power Plants (one per terminal)

# Follow the prompts: enter a 4-digit port (e.g. 9001) and a unique plant ID
./gradlew run --args='plant.PlantApp'

Run at least one plant before starting the energy provider. The ring self-organizes as plants join.

3. Renewable Energy Provider

./gradlew run --args='energyprovider.renewableEnergyProvider'

Publishes a new energy request every 10 seconds.

4. Administration Client (optional)

./gradlew run --args='administration.AdministrationClient'

CLI menu to list plants and query CO2 pollution statistics.

REST API

Method	Endpoint	Description
GET	/plants	List all registered plants
POST	/plants/add	Register a new plant (returns 409 if ID exists)
GET	/plants/get/{id}	Get plant by ID
DELETE	/plants/delete/{id}	Deregister a plant
GET	/plants/pollution/statistics?t1=...&t2=...	Average CO2 between two timestamps

gRPC Service

Defined in plant_comms.proto:

service PlantCommunication {
  rpc SendGreetingsMessage(GreetingsMessage)   returns (GreetingsResponse);
  rpc SendElectionMessage(ElectionMessage)     returns (ElectionResponse);
  rpc SendFarewellMessage(FarewellMessage)     returns (FarewellResponse);
}

• Greetings — announce a new plant joining the ring.
• Election — circulate bids through the ring (lowest price wins).
• Farewell — notify plants when one is shutting down.

Project Structure

src/main/java/
├── administration/
│   ├── AdministrationServer.java          # Spring Boot server + MQTT subscriber
│   ├── AdministrationClient.java          # CLI client for admin queries
│   ├── controller/
│   │   └── PlantsController.java          # REST endpoints
│   ├── service/
│   │   └── PlantService.java              # In-memory plant registry
│   └── models/
│       ├── PlantInfo.java
│       └── PollutionReading.java
├── energyprovider/
│   └── renewableEnergyProvider.java       # Publishes energy requests via MQTT
├── plant/
│   ├── PlantApp.java                      # Entry point for each power plant
│   ├── PowerPlant.java                    # Orchestrates all plant subsystems
│   ├── GrpcService.java                   # gRPC server + client for ring comms
│   ├── MqttHandler.java                   # MQTT subscribe/publish
│   ├── RingNetwork.java                   # Ring topology + election algorithm
│   ├── PlantClient.java                   # REST client for admin registration
│   ├── models/
│   │   ├── PlantInfo.java
│   │   └── EnergyRequestInfo.java
│   └── sensors/
│       ├── PollutionMonitor.java          # Sensor polling + MQTT publish
│       └── SensorBuffer.java              # Thread-safe buffer
├── Simulators/
│   ├── Simulator.java                     # Abstract sensor base class
│   ├── PollutionSensor.java               # CO2 Gaussian noise simulator
│   ├── Buffer.java                        # Buffer interface
│   └── Measurement.java                   # Sensor measurement model
└── proto/
    └── plant_comms.proto                  # gRPC service definition