Distributed-Tic-Tac-Toe

This project implements a distributed client-server Tic Tac Toe game using Java RMI (Remote Method Invocation). Players can connect to a central server, join game sessions, and play against opponents in real-time with automatic matchmaking.

Note

A command-line interface is available in /cli for testing purposes. The GUI version is recommended for end-users.

Features

• Distributed Architecture: Server handles game logic, clients manage UI
• Dynamic Session Management: Auto-scales game sessions as players connect
• Rematch System: Players can restart games after completion
• Heartbeat Monitoring: Detects disconnected players automatically
• Modern GUI: Clean interface with game board, status updates, and controls
• Connection Security: Custom security manager for RMI communication

Project Structure

Class	Purpose	Key Features
ServerMain	Server entry point	Starts RMI registry, registers primary service
TicTacToeServer	Session manager	Creates/destroys game sessions, manages player allocation
TicTacToeServiceImpl	Game logic core	Move validation, win detection, player management
ClientMain	Client entry point	Launches game GUI
TicTacToeGUI	Player interface	Game board, status display, input handling
TicTacToeClient	Client logic	Server communication, game state management
PlayerCallbackImpl	Server→client comms	Real-time updates, heartbeat monitoring
MySecurityManager	Security config	Enables RMI connections without strict policy files
GameConstants	Shared config	Board size, player symbols, game rules

Prerequisites

• Java JDK 17+
• Network connectivity between machines
• RMI ports open (1099 + 1100-1106 by default)

Setup & Execution

1. Compile Code

javac -d bin src/server/*.java src/client/*.java src/common/*.java src/security/*.java

2. Start Server

java -cp bin -Djava.rmi.server.codebase=file:bin/ security.MySecurityManager server.ServerMain 192.168.1.10

Note

Replace 192.168.1.10 with server's actual IP

3. Start Clients

java -cp bin -Djava.rmi.server.codebase=file:bin/ security.MySecurityManager client.ClientMain

Note

Run on player machines, enter server IP when prompted

Game Flow

1. Client Connection

Players connect via the GUI by entering server details:

• Server IP (e.g., localhost for local testing)
• Client IP (auto-detected or manually entered)

Error Handling:

• Unreachable servers show connection timeout messages
  

  

• Invalid IP formats trigger validation warnings
• Duplicate player names are rejected

2. Session Matching

• Server automatically pairs available players
• New game sessions are created on-demand
• Players see "Waiting for opponent" status until matched

3. Gameplay Loop

Players take turns making moves on the board:

Features:

• Turn indication ("YOUR TURN" vs "Opponent's turn")
• Visual board updates after each move
• Real-time move validation (prevents invalid placements)

4. Win/Draw Detection

Game automatically detects end conditions:

• Win: 3-in-a-row patterns
• Draw: Full board with no winner
  

Error Recovery:

• Network drops trigger automatic reconnection attempts
• Missing heartbeats mark players as "disconnected"
• Session timeouts after 30 seconds of inactivity

5. Rematch System

After game completion:

• Both players get rematch prompts
• New game starts if both choose "Play Again"
• Session dissolves if either player quits

6. Graceful Exit

Players can quit anytime via:

• "Quit Game" button during gameplay
• Window close (X) button (NOT ON WINDOWS)
• Console interrupt (Ctrl+C) for CLI clients

Termination Sequence:

1. Client sends disconnect notification
2. Server frees game resources
3. Opponent receives "Player left" notification
4. Session automatically closes after 60 seconds

Configuration Options

Parameter	Location	Description
MAX_SESSIONS	TicTacToeServer.java	Max concurrent game sessions
portBase	TicTacToeServer.java	Starting port for game sessions
sun.rmi.transport.*	TicTacToeClient.java	Network timeout settings
Color constants	TicTacToeGUI.java	UI color scheme

Key Design Patterns

• Observer Pattern: Callbacks for game state updates
• Singleton Pattern: Central server instance
• Factory Pattern: Dynamic session creation
• Asynchronous Processing: Non-blocking game operations

Troubleshooting

• Connection Issues: Verify IPs match server's network interface
• Port Conflicts: Change portBase in TicTacToeServer.java
• Session Limits: Increase MAX_SESSIONS if needed
• Timeout Errors: Adjust sun.rmi.transport.* properties