0124-architecture-patterns

Clean architecture structures backend code by separating domain logic, use cases, and infrastructure into layers with inward-only dependencies. Hexagonal architecture models the system around ports and adapters so the domain core stays framework-free while infrastructure implementations can be swapped freely.

Dependency cycles occur when code violates inward dependency rules by allowing outer layers to be imported by inner layers. You can resolve these cycles by enforcing imports that flow inward only, ensuring controllers and infrastructure depend on use cases rather than the reverse.

The best way to unit test use cases without a running database is by defining abstract ports for infrastructure access and injecting in-memory adapters. This approach keeps use-case tests database-free while verifying application workflows.

Refactoring a monolith into bounded contexts using domain-driven design involves establishing tactical modeling with entities, value objects, aggregates, and repositories. This keeps models coherent and resilient while defining clear boundaries between domain logic and application workflows.

Yes, you can implement ports and adapters when designing a new microservice by modeling the system around hexagonal architecture. This keeps the domain core framework-free while abstract interfaces allow infrastructure implementations to be swapped freely.

You need domain-driven design invariants like value objects and aggregates when modeling complex domain logic to keep models coherent and resilient. These tactical patterns enforce business rules within bounded contexts while preventing tightly coupled, hard-to-test backend layers.