hexagonal-architecture

You separate business logic from infrastructure dependencies by applying hexagonal architecture, which isolates core domain rules into ports and adapters, ensuring business rules remain independent of frameworks, databases, and external APIs.

The best way to refactor tightly coupled legacy code is using hexagonal architecture to extract business rules from framework and persistence details into explicit ports, allowing infrastructure swaps without modifying core logic and enabling simple unit testing with in-memory fakes.

Yes, hexagonal architecture supports multi-interface use cases by routing HTTP, CLI, queue worker, and cron job requests through separate adapters to the same core use cases, allowing multiple interface support without rewriting core business logic.

Yes, this dependency inversion approach supports cross-language service implementations across TypeScript, Java, Kotlin, and Go, applying explicit domain boundaries and testable application orchestration consistently regardless of the underlying language ecosystem.

To unit test use cases mixed with Stripe SDK calls and Postgres queries, refactor using ports and adapters to inject in-memory fakes, enabling you to test application orchestration and business rules without hitting real payment or database infrastructure.

You should avoid ports and adapters when application complexity is low, if you do not require multiple interface support, or when infrastructure swaps are unlikely, as the overhead of explicit domain boundaries and dependency inversion may outweigh maintainability benefits.