clean-ddd-hexagonal

Structure a backend service using domain-driven design by separating domain, application, and infrastructure layers. Enforce the Dependency Rule for inward dependencies only, utilizing tactical patterns like entities, value objects, and aggregates to isolate business logic.

The best way to separate business logic from data persistence is implementing hexagonal architecture. Define ports and adapters to isolate the core domain from infrastructure concerns, ensuring your maintainable systems remain testable and scalable.

You need aggregates and value objects in domain modeling when enforcing business invariants and encapsulating domain logic. These tactical patterns structure the domain layer, maintaining clear boundaries and ensuring consistent state transitions across your backend service.

Hexagonal architecture does not require specific frameworks. It is a structural design pattern enforcing the Dependency Rule through ports and adapters, allowing you to decouple core application logic from infrastructure tools using plain code interfaces.

Enforce the Dependency Rule by ensuring all dependencies point inward toward the domain layer. Infrastructure and application layers depend on the domain, never the reverse, guaranteeing that business logic remains isolated from external concerns like data persistence.

Domain logic leaks into infrastructure when architectural boundaries are unclear. Applying hexagonal architecture with explicit ports and adapters separates use cases from data persistence, ensuring business rules stay within the domain layer and preventing leakage.