hexagonal

Hexagonal architecture decouples business logic from infrastructure by defining Ports as interfaces and implementing Adapters as interchangeable layers. This isolates core logic so storage, external services, and dependencies can swap without affecting business rules.

Ports define contracts that business logic depends on, typically as Context.Tag interfaces. Adapters implement those contracts as Layer implementations—production adapters connect real infrastructure, while test adapters provide in-memory alternatives for testing without mocks.

Hexagonal architecture enables mock-free testing by swapping production adapters with test adapters. Implement a test adapter that provides in-memory storage or stub services, inject it via dependency injection, and run tests against real business logic with predictable test data.

Use hexagonal architecture when your application requires stable core logic with interchangeable storage and external services. It suits systems where you need multiple implementations of the same dependency—such as different databases or payment providers—without modifying business logic.

Yes. Hexagonal architecture is built on dependency injection principles. Define Ports as interfaces, create Adapter implementations, and inject the appropriate adapter at runtime. This enables switching between production and test adapters without code changes.

Yes. External services are implemented as Adapters behind Ports. Define a Port interface for the service contract, create a live Adapter that calls the real service, and a test Adapter that returns stub responses. Dependency injection swaps them as needed.