hexagonal-architect

Hexagonal architecture isolates domain logic by organizing codebases around ports and adapters, enforcing inward dependencies so business rules remain decoupled from frameworks, databases, and external services.

Structure a NestJS project using ports and adapters by applying folder templates for domain, application, infrastructure, and shared concerns, utilizing port-based dependency injection to separate input and output boundaries.

Yes, you can refactor existing codebases by reorganizing folders and dependency flows to match hexagonal architecture, shifting implementation details into adapters while protecting core domain logic from external changes.

Ports and adapters architecture uses layer-specific testing strategies, allowing you to test domain logic independently, validate application use cases, and mock infrastructure adapters to isolate external dependencies.

Dependency flow matters in domain-driven design because enforcing inward dependencies ensures your domain layer never references infrastructure, keeping business logic pure and swappable without modifying core rules.

Hexagonal architecture may be excessive for small or prototype projects, as the overhead of defining ports, adapters, and strict layer separation introduces complexity that outweighs the benefits of domain isolation in simple applications.