Clean Architecture Layers

Learn to structure applications with clean architecture layers for maintainability and testability.

Background

Clean architecture separates concerns into layers:

• Domain Layer: Core business entities and interfaces (User, Product, etc.)
• Service Layer: Business logic that operates on domain entities
• Repository Layer: Data persistence and retrieval

The key principle is dependency inversion: inner layers (domain) define interfaces that outer layers (infrastructure) implement. The domain layer has no dependencies on external concerns like databases or frameworks.

Your Task

Implement a simple user management system with clean layers:

1. Define a User domain entity
2. Create a UserRepository interface in the domain layer
3. Implement InMemoryUserRepo that satisfies the interface
4. Create a UserService that uses the repository through the interface

Clean Architecture Layers

~20 mineasy

Implement layered architecture with domain, service, and repository

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Key Concepts

• Dependency Inversion: Inner layers define interfaces; outer layers implement them
• Layered Architecture: Domain → Service → Infrastructure with clear boundaries
• Interface-Driven Design: Services depend on interfaces, not concrete implementations
• Testability: Easy to swap implementations (in-memory vs database) for testing
• Separation of Concerns: Business logic separated from data persistence details