Hexagonal Architecture (Ports and Adapters)

Isolate the domain logic from the outside world.

“Allow an application to equally be driven by users, programs, automated test or batch scripts, and to be developed and tested in isolation from its eventual run-time devices and databases.” – Alistair Cockburn

Domain-Centric.

graph TD
    subgraph Core [Domain Core]
    Logic
    end
    subgraph Ports [Ports/Interfaces]
    Service -->|Uses| RepoInterface
    Driver -->|Calls| ServiceInterface
    end
    subgraph Adapters [Adapters]
    WebController -->|Calls| ServiceInterface
    RepoImpl -->|Implements| RepoInterface
    end

When to use

  • Long-lived applications.
  • Domain-Driven Design (DDD).
  • Complex Business Logic.

Explanation

  • Core: Pure logic. No dependencies on DB or Web.
  • Ports: Interfaces defining how to talk to the core (Inbound) and how the core talks out (Outbound).
  • Adapters: Implementations (Rest API, Postgres DB, CLI).

Pros and Cons

Pros Cons
  • Database/Framework independent
    		•
  • Over-engineering for simple CRUD
    		•
  • High Testability
    		•
  • Many files/interfaces
    		•

    Code example

    Typescript