Server Architecture - Best Practices

Separation of Concerns

This project follows a clean separation of concerns pattern:

📁 File Structure

src/
├── index.ts          # Entry point
├── server.ts         # HTTP server setup & lifecycle
├── app.ts           # Express app configuration
├── config/
│   └── env.ts       # Environment configuration
├── routes/
│   └── index.ts     # Route aggregation
├── controllers/      # Business logic
├── services/        # External service integration
├── models/          # Data models
├── middlewares/     # Custom middleware
├── repositories/    # Data access layer
└── utils/           # Utility functions

🔧 Key Components

1. app.ts - Express Application Configuration

• Purpose: Configure Express app, middleware, and routes
• Responsibilities:
  • Security middleware (helmet, cors)
  • Body parsing
  • Logging (morgan)
  • Route registration
  • Error handling
  • Health checks

2. server.ts - HTTP Server Management

• Purpose: Handle server lifecycle and process management
• Responsibilities:
  • Start HTTP server
  • Graceful shutdown handling
  • Process signal handling (SIGTERM, SIGINT)
  • Uncaught exception handling
  • Unhandled promise rejection handling

3. index.ts - Application Entry Point

• Purpose: Clean entry point that imports server
• Benefits:
  • Single responsibility
  • Easy testing
  • Clear dependency chain

🚀 Benefits of This Separation

1. Testability

// Easy to test app configuration without starting server
import app from './app';
import request from 'supertest';

describe('App', () => {
  it('should return health status', async () => {
    const response = await request(app).get('/health');
    expect(response.status).toBe(200);
  });
});

2. Flexibility

• Can run app without server (for testing)
• Can run server with different configurations
• Easy to swap HTTP server implementation

3. Maintainability

• Clear separation of concerns
• Easy to understand what each file does
• Modular architecture

4. Production Ready

• Graceful shutdown handling
• Proper error handling
• Environment-specific configuration
• Security middleware

🔄 Development Workflow

1. Development: npm run dev

   • Uses nodemon for auto-restart
   • Runs on development environment

2. Production: npm run build && npm start

   • Compiles TypeScript
   • Runs on production environment

📝 Best Practices Implemented

Security

• ✅ Helmet for security headers
• ✅ CORS configuration
• ✅ Environment-based configuration
• ✅ Input validation (ready for Zod)

Error Handling

• ✅ Global error handler
• ✅ 404 handler
• ✅ Uncaught exception handling
• ✅ Graceful shutdown

Monitoring

• ✅ Health check endpoint
• ✅ Request logging (development)
• ✅ Environment logging

Code Organization

• ✅ Separation of concerns
• ✅ Modular architecture
• ✅ Clean entry point
• ✅ TypeScript support

🎯 Next Steps

1. Add Routes: Create specific route modules in routes/
2. Add Controllers: Implement business logic in controllers/
3. Add Models: Define data models in models/
4. Add Services: External service integration in services/
5. Add Middleware: Custom middleware in middlewares/
6. Add Validation: Use Zod for request validation
7. Add Database: Connect to MongoDB using Mongoose
8. Add Authentication: JWT implementation
9. Add Testing: Unit and integration tests
10. Add Documentation: API documentation with Swagger

🔧 Environment Variables

Create .env.development and .env.production files:

PORT=8000
NODE_ENV=development
JWT_SECRET=your-secret-key
MONGO_URI=mongodb://localhost:27017/your-db
ALLOWED_ORIGINS=http://localhost:3000