MPchat - Multi-Client Chat Application

Author: Martynas Prascevicius University: University of Greenwich Course: COMP1549 - Network and Operating System Principles Year: 2024-25

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Overview

MPchat is a multi-client chat application built with JavaFX, demonstrating concurrent networking, server-client architecture, and GUI development in Java. The application supports multiple simultaneous client connections with a custom-styled graphical interface.

Key Features

• Multi-threaded Server - Handles multiple concurrent client connections
• JavaFX GUI - Modern graphical interface with custom styling
• Real-time Messaging - Instant message broadcasting to all connected clients
• Unit Testing - JUnit test suite for server functionality
• Custom Styling - CSS-based theming with background images

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Technical Stack

• Language: Java (OpenJDK 23.0.2)
• GUI Framework: JavaFX 23.0.2
• Testing: JUnit 4.13.2
• Build Tool: Manual compilation (shell scripts)
• Architecture: Server-client model with multi-threading

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Project Structure

MPchat/
├── src/
│   ├── Server.java          # Multi-threaded server implementation
│   ├── ClientHandler.java   # Handles individual client connections
│   ├── ChatClient.java      # JavaFX client GUI
│   ├── MyMessageBox.java    # Custom message box component
│   ├── ServerTest.java      # JUnit test suite
│   ├── styles.css           # Custom CSS styling
│   └── bg.png               # Background image asset
├── lib/                     # JUnit and Hamcrest libraries
└── javafx-sdk-23.0.2/       # JavaFX SDK (not included in repo)

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Getting Started

Prerequisites

• Java Development Kit (JDK) 21+
• JavaFX SDK 23.0.2 - Download here
• macOS/Linux environment (scripts are bash-based)

Installation

1. Clone the repository:

   git clone https://github.com/mp-c0de/MPchat-JavaFX.git
   cd MPchat-JavaFX

2. Download and extract JavaFX SDK 23.0.2 into the MPchat/ directory:

   MPchat/javafx-sdk-23.0.2/
   

Running the Application

1. Start the Server

java MPchat/src/Server.java 2000

The server will start listening on port 2000.

2. Launch Multiple Clients

Use the provided script to start multiple client windows:

bash sclients.sh 3

This will open 3 JavaFX client windows that can communicate with each other.

3. Run Unit Tests

bash runtests.sh

This executes the JUnit test suite for the server functionality.

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Architecture

Server Design

The server uses a multi-threaded architecture:

• Main server thread accepts incoming connections on a specified port
• Each client connection is handled by a separate ClientHandler thread
• Messages are broadcast to all connected clients in real-time
• Thread-safe message distribution using concurrent collections

Client Design

The JavaFX client provides:

• Text input field for composing messages
• Message display area showing chat history
• Send button for submitting messages
• Custom CSS styling with background image
• Automatic reconnection handling

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Testing

The project includes a comprehensive JUnit test suite (ServerTest.java) that verifies:

• Server initialisation and port binding
• Multiple concurrent client connections
• Message broadcasting functionality
• Graceful shutdown and resource cleanup

Run tests:

bash runtests.sh

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Features Demonstrated

Concurrent Connections

• Multiple clients can connect simultaneously
• Each client operates independently in its own thread
• No blocking between client operations

Real-time Communication

• Messages are instantly broadcast to all connected clients
• Server maintains a list of active connections
• Clients can join or leave at any time

GUI Development

• Custom JavaFX interface with CSS styling
• Responsive layout design
• Visual feedback for user actions

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Learning Outcomes

This project demonstrates proficiency in:

• Networking: Socket programming, server-client architecture
• Concurrency: Multi-threading, thread synchronisation, concurrent collections
• GUI Development: JavaFX, event handling, CSS styling
• Testing: JUnit unit testing, test-driven development
• Software Engineering: Clean code structure, separation of concerns

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Development Notes

Tested Environment

• OS: macOS Sequoia 15.3.2
• Java: OpenJDK 23.0.2
• Shell: zsh

Known Limitations

• No authentication or user management
• No message persistence (chat history is lost on disconnect)
• Fixed port configuration (hardcoded to 2000)
• No encryption (plain text communication)

Potential Improvements

• Add user authentication
• Implement message history storage
• Add private messaging between specific clients
• Integrate TLS/SSL for secure communication
• Create configuration file for server settings

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License

This project was created for academic purposes as part of university coursework.

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Author

Martynas Prascevicius

• Email: mpcode@mpcode.dev
• Website: mpcode.dev
• LinkedIn: linkedin.com/in/mpc0de
• GitHub: github.com/mp-c0de

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Built for COMP1549 coursework at University of Greenwich