portdriven

Portdriven is a software design philosophy that centers system architecture on explicit interfaces, or ports, through which external actors and subsystems interact with the core domain. In a portdriven design, the business logic depends on abstract contracts rather than on concrete implementations, allowing interaction to occur through well-defined channels.

Ports define the allowed operations and data flows for each direction of interaction (input, output, or both). Adapters implement these ports for specific technologies or platforms, such as databases, message buses, user interfaces, or external services. By isolating business rules from infrastructure, portdriven aims to improve testability, replaceability, and maintainability.

Historically it shares a lineage with hexagonal and clean architecture, where the core domain remains isolated and communicates with the outside via ports. This alignment makes it easier to swap frameworks, databases, or external services without touching the domain model.

Implementation typically involves mapping use cases to ports, validating them as stable contracts, and creating adapters that fulfill those contracts. Common practice includes tooling for port versioning, contract testing, and ensuring that adapters do not leak implementation details into the domain.

Example: in an e-commerce order service, ports might include placeOrder, cancelOrder, and notifyShipment. Adapters implement these ports against a relational database, a message broker, and an external payment gateway, respectively, while the domain logic remains unaware of technology choices.

Advantages include decoupled layers, simplified testing, and easier technology upgrades. Critics warn that portdriven can introduce boilerplate and unnecessary indirection if over-applied. It is most effective when used to manage the boundary between stable business rules and rapidly changing infrastructure.

See also: hexagonal architecture, clean architecture, ports and adapters, interface segregation.