clean-architecture

To enforce clean architecture boundaries during refactoring, you must ensure dependencies point inward across the Domain, Application, Interface Adapters, and Frameworks layers. This keeps business rules isolated from external systems, making the software maintainable and testable.

The dependency rule in clean architecture states that source code dependencies must point inward toward the Domain and Use Cases layers. Outer layers like Frameworks and Drivers can depend on inner layers, but inner layers must never depend on outer ones.

Structure code by placing business rules in Domain entities and user-centric actions in Use Case interactors. Map each use case to repository interfaces, then implement interface adapters to convert data between these boundaries and external frameworks or drivers.

Yes, you can refactor a legacy codebase into testable layers by reorganizing existing services into well-defined entities, interactors, and boundary interfaces. This separation of concerns enables parallel development and safer changes by isolating business rules from external systems.

You need clean architecture for software design when your system requires strict separation of concerns, high testability, and replaceable external components. It is particularly useful for organizing complex systems into concentric layers to enable parallel development and safer modifications.

The best way to separate business rules from frameworks is to apply the dependency rule, placing business logic in the inner Domain and Application layers. Interface adapters then act as boundaries, adapting external framework requests to inner layer formats without inward dependencies.