JavaFx_Raft3D_Visualization

Visualization of Raft consensus algorithm for 3d printers using JavaFx (GUI), Spring Boot (REST API Endpoints GET/POST) and RabbitMQ (Message Broker) in Java 21.

Project Overview

The Raft Consensus Algorithm

This project implements and visualizes the Raft lifecycle for 3D printers using a 3 node cluster. Each node is a Spring Boot application that communicates with the others using RabbitMQ. The state of each node is visualized in real-time using a JavaFX GUI.

For a quick visual understanding refer to the image below:

imgsrc: RAFT Protocol by Swayam Raina on Medium

In a distributed system, Raft ensures all nodes agree on a single source of truth, even if some nodes fail.

Nodes transition through three states:

• 🔵 FOLLOWER (Blue): The default state.Nodes remain here as long as they receive regular "heartbeats" from a Leader.
• 🟠 CANDIDATE (Orange): If a follower doesn't receive a heartbeat within its randomized election timeout (3-5s), it becomes a candidate and requests votes.
• 🟢 LEADER (Green): The winner of the election. If a Candidate receives a majority of votes, it becomes the Leader and begins sending periodic heartbeats (every 1s) to maintain authority.
• Note: To simulate a realistic and dynamic cluster, the leader automatically steps down after a randomized tenure (4-7s), forcing a new election sequence.

Prerequisites

• Java 21 (e.g., BellSoft Liberica JDK with JavaFX bundled)
• RabbitMQ running on localhost:5672 (default guest/guest credentials)
• Maven (Wrapper included in project)

Technical Stack

• Language : Java 21 LTS
• REST APIs: Spring Boot 4.0
• Build Tool: Maven
• Message Broker: RabbitMQ
• GUI: JavaFX

Running the Project

The cluster consists of 3 Spring Boot nodes running on different ports (8080, 8081, 8082). You need to launch each node in a separate terminal window, and then launch the JavaFX GUI.

1. Start the RabbitMQ Broker

Ensure your RabbitMQ server is running on localhost.

2. Start the Raft Nodes

Open 3 separate terminals, navigate to the project root, and run:

Terminal 1 (Node 1 - Port 8080):

./mvnw spring-boot:run -Dspring-boot.run.profiles=node1

Terminal 2 (Node 2 - Port 8081):

./mvnw spring-boot:run -Dspring-boot.run.profiles=node2

Terminal 3 (Node 3 - Port 8082):

./mvnw spring-boot:run -Dspring-boot.run.profiles=node3

3. Start the JavaFX Visualization

Open a 4th terminal and run the GUI:

./mvnw javafx:run

Simulation Details

• The GUI updates dynamically every 2 seconds by polling the REST endpoints /raft/state of each node.
• The visualization runs for exactly 30 seconds. After 30 seconds, the simulation halts, displays a "Hope You Enjoyed Visualization of Raft" alert popup, and gracefully shuts down.

Architecture

• RaftConsensusService.java: Core Raft logic. Manages election timeouts, leader heartbeats, state transitions, and RabbitMQ message broadcasting/consumption.
• Raft3DGui.java: JavaFX application. Uses asynchronous HttpClient to poll node states without blocking the JavaFX Application Thread.
• RaftMessageProducer.java / RaftMessageConsumer.java: RabbitMQ integration for inter-node communication.
• application.yaml: Uses Spring Profiles (node1, node2, node3) to isolate ports and node IDs while sharing the same codebase.

Output Screenshots:

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