Layered architecture

Layered architecture organizes presentation, application, domain, and infrastructure tiers with explicit dependency direction. It is a pragmatic default for many enterprise apps when teams need familiar structure and transaction boundaries align with use cases. Layers are logical; physical deployment may still be monolithic.

On interviews: map a feature through layers on a whiteboard. Explain where DTO mapping happens and why domain should not call upward.

Common pitfalls: strict layers that forbid legitimate cross-cutting concerns; presentation logic leaking into application services; database schema driving domain design.

The trade-off is flexibility versus complexity—know when the simpler path is enough.

Checklist:

• Each layer has documented responsibilities.
• Dependencies point inward toward domain.
• Cross-layer types mapped at boundaries.
• Integration tests span realistic layer collaborations.