Clean Architecture

To structure a software project using clean architecture, organize your codebase into concentric layers: entities, use cases, interface adapters, and frameworks. This separation ensures dependencies always point inward, keeping core business logic independent from external concerns like UI or databases.

The dependency rule in clean architecture mandates that source code dependencies must only point inward. Outer layers like frameworks, drivers, and interface adapters can depend on inner layers, but inner entities and use cases must never depend on outer concerns.

Domain-driven design complements clean architecture by organizing code around business domains rather than technical layers. This modularity places core domain logic at the center, ensuring use cases and entities remain independent of external implementations for better maintainability.

To test business logic independent of the database and UI, apply clean architecture to isolate use cases and entities within inner layers. Using dependency injection, you decouple core logic from external frameworks, facilitating high testability without requiring actual database or UI connections.

You should avoid clean architecture for small or prototype-level software design where strict separation of concerns and layered modularity introduce unnecessary overhead. The pattern suits complex systems needing high scalability, maintainability, and strict dependency rule enforcement.