Architecture Patterns

Common architectural patterns and design decisions.

Layered Architecture

Presentation → Business Logic → Data Access → Database

Clean Architecture

        Controllers
             ↓
        Use Cases
             ↓
         Entities

Common Patterns

Repository

interface UserRepository {
    findById(id): User
    save(user): void
}

Service Layer

class UserService {
    constructor(repo: UserRepository)
    createUser(data): User
}

Dependency Injection

• Pass dependencies via constructor
• Program to interfaces, not implementations
• Enables testing with mocks

Design Principles

• SOLID: Single responsibility, Open/closed, Liskov, Interface segregation, Dependency inversion
• DRY: Don't repeat yourself
• KISS: Keep it simple
• YAGNI: You aren't gonna need it