Advanced Clean Hexagonal Architecture

Hexagonal architecture isolates business logic by defining ports as interfaces for external interactions and adapters as implementations for specific frameworks or services. Structure your system with a domain layer containing pure business rules, an application layer orchestrating use cases, and an infrastructure layer housing adapters for databases, APIs, and messaging. This separation enables framework-agnostic domain code and seamless technology swaps.

Ports are interfaces defining contracts for external interactions; adapters are concrete implementations fulfilling those contracts. A port specifies what your domain needs (e.g., UserRepository interface), while adapters implement it for specific tools (PostgreSQL adapter, MongoDB adapter). This inversion of dependency ensures your domain depends on abstractions, not external frameworks.

Yes. Hexagonal architecture enables framework transitions by keeping domain logic independent of framework choices. Replace the adapter layer—swap Express for Fastify, PostgreSQL for MongoDB—without touching domain or application code. Ports remain constant; only adapters change, preserving business rule integrity and reducing migration risk.

Organize three layers: domain (pure business rules, no dependencies), application (use case orchestration, ports), and infrastructure (adapter implementations). Testability follows from this isolation—mock ports in unit tests, inject real adapters in integration tests. Strict dependency inversion ensures domain logic never imports infrastructure, enabling fast, isolated testing.

Enforce dependency inversion—domain and application layers depend only on ports, never infrastructure. Maintain strict separation of concerns by isolating business rules from framework concerns. Ensure every external interaction flows through defined ports. Validate that adapters remain interchangeable; if swapping implementations requires domain changes, the boundary is misplaced.