Document Version Control

Version Date Author Description
1.0 2025-05-03 System Design Team Initial version - Complete system design
1.1 2025-05-04 System Design Team Added security considerations for WebSocket
1.2 2025-05-05 System Design Team Updated database schemas, added Redis caching
1.3 2025-05-10 System Design Team Added monitoring and logging specifications
1.4 2025-05-15 System Design Team Updated API endpoints with rate limiting
1.5 2025-05-20 System Design Team Added future enhancement section

Review History

Date Reviewer Role Comments
2025-05-03 John Smith Lead Architect Approved initial design
2025-05-05 Jane Doe Security Engineer Suggested security enhancements
2025-05-10 Mike Johnson DevOps Lead Added deployment considerations
2025-05-15 Sarah Wilson Product Manager Verified feature alignment

Document Status

Table of Contents

  1. Introduction
  2. System Architecture
  3. Component Design
  4. API Design
  5. Security Considerations
  6. Performance Considerations
  7. Error Handling
  8. Testing Strategy
  9. Deployment
  10. Monitoring & Logging
  11. Future Enhancements
  12. Appendix

1. Introduction

1.1 Purpose

This document outlines the software design for a web-based Tic-Tac-Toe game that allows players to compete against each other over the internet in real-time.

1.2 Scope

The system will provide:

1.3 Definitions and Acronyms

2. System Architecture

2.1 High-Level Architecture

+-------------------+          +-------------------+          +-------------------+
|   Client Layer    |  <---->  |   Server Layer    |  <---->  |   Database Layer  |
| (React Frontend)  |          | (Node.js Backend) |          | (MongoDB/Redis)   |
+-------------------+          +-------------------+          +-------------------+

2.2 Technology Stack

3. Component Design

3.1 Frontend Components

3.1.1 Authentication Module

INTERFACE AuthComponent:
  FUNCTION login(username, password) -> Promise
  FUNCTION register(username, password, email) -> Promise
  FUNCTION logout() -> void
  FUNCTION getCurrentUser() -> User OR null

3.1.2 Game Board Component

INTERFACE GameBoardProps:
  gameState: GameState
  onCellClick: FUNCTION(row, col) -> void
  disabled: boolean
  currentPlayer: Player

INTERFACE GameState:
  board: CellValue[3][3]
  currentTurn: PlayerSymbol
  winner: PlayerSymbol OR null
  gameStatus: GameStatus

TYPE CellValue = 'X' OR 'O' OR null
TYPE PlayerSymbol = 'X' OR 'O'
TYPE GameStatus = 'waiting' OR 'in_progress' OR 'completed'

3.1.3 Game Room Component

INTERFACE GameRoomProps:
  roomId: string
  players: Player[]
  gameState: GameState
  onMove: FUNCTION(row, col) -> void
  onChat: FUNCTION(message) -> void
  onLeaveRoom: FUNCTION() -> void

3.1.4 Lobby Component

INTERFACE LobbyProps:
  availableRooms: GameRoom[]
  onCreateRoom: FUNCTION() -> void
  onJoinRoom: FUNCTION(roomId) -> void
  onRefresh: FUNCTION() -> void

3.2 Backend Components

3.2.1 Game Engine

CLASS GameEngine:
  PRIVATE board: CellValue[3][3]
  PRIVATE currentTurn: PlayerSymbol
  PRIVATE gameStatus: GameStatus
  
  FUNCTION constructor()
  FUNCTION makeMove(row, col, player) -> MoveResult
  FUNCTION checkWinner() -> PlayerSymbol OR null
  FUNCTION isValidMove(row, col) -> boolean
  FUNCTION resetGame() -> void
  FUNCTION getGameState() -> GameState

INTERFACE MoveResult:
  success: boolean
  error: string (optional)
  winner: PlayerSymbol (optional)
  gameStatus: GameStatus

3.2.2 Room Manager

CLASS RoomManager:
  PRIVATE rooms: Map
  
  FUNCTION createRoom(host) -> GameRoom
  FUNCTION joinRoom(roomId, player) -> boolean
  FUNCTION leaveRoom(roomId, player) -> void
  FUNCTION getRoomById(roomId) -> GameRoom OR null
  FUNCTION getAvailableRooms() -> GameRoom[]
  FUNCTION removeRoom(roomId) -> void

INTERFACE GameRoom:
  id: string
  players: Player[]
  gameEngine: GameEngine
  status: RoomStatus
  createdAt: Date
  chatHistory: ChatMessage[]

3.2.3 WebSocket Handler

CLASS WebSocketHandler:
  PRIVATE io: Server
  PRIVATE roomManager: RoomManager
  
  FUNCTION handleConnection(socket) -> void
  FUNCTION handleDisconnection(socket) -> void
  FUNCTION handleGameMove(socket, data) -> void
  FUNCTION handleChatMessage(socket, data) -> void
  FUNCTION broadcastGameState(roomId) -> void
  FUNCTION broadcastToRoom(roomId, event, data) -> void

3.3 Database Schemas

3.3.1 User Schema (MongoDB)

SCHEMA User:
  _id: ObjectId
  username: String
  email: String
  passwordHash: String
  stats: {
    gamesPlayed: Number
    wins: Number
    losses: Number
    draws: Number
  }
  createdAt: Date
  lastLogin: Date

3.3.2 Game History Schema (MongoDB)

SCHEMA GameHistory:
  _id: ObjectId
  roomId: String
  players: Array[
    {
      userId: ObjectId
      username: String
      symbol: String
    }
  ]
  moves: Array[
    {
      player: ObjectId
      position: { row: Number, col: Number }
      timestamp: Date
    }
  ]
  winner: ObjectId
  startTime: Date
  endTime: Date
  chatLogs: Array[
    {
      userId: ObjectId
      message: String
      timestamp: Date
    }
  ]

4. API Design

4.1 REST API Endpoints

Authentication

Game Management

Statistics

4.2 WebSocket Events

Client to Server

Server to Client

5. Security Considerations

5.1 Authentication & Authorization

5.2 Input Validation

5.3 Communication Security

6. Performance Considerations

6.1 Scalability

6.2 Caching Strategy

6.3 Optimization

7. Error Handling

7.1 Client-Side Error Handling

ENUM ErrorCode:
  NETWORK_ERROR
  INVALID_MOVE
  ROOM_FULL
  UNAUTHORIZED
  SERVER_ERROR

INTERFACE ErrorResponse:
  code: ErrorCode
  message: string
  details: any (optional)

7.2 Server-Side Error Handling

8. Testing Strategy

8.1 Unit Testing

8.2 Integration Testing