Hexagonal Architecture

Hexagonal architecture, also known as the Ports-and-Adapters architecture, is a design pattern aimed at separating business logic from infrastructure. This allows for better testability, flexibility, and maintainability of software applications by using various interfaces (ports) and implementations (adapters) to enable interaction with external systems.

Use this profile to understand the building block briefly, place it in the model, and switch to the 360° assessment when needed.

Content type

Concept

Theoretical construct: explains a term, principle, or mental model.

Classification level

Structure

What organizes, connects, or makes decisions possible.

Available perspectives

Open this building block directly in an already curated view.

360°

In brief

Hexagonal architecture in brief

Hexagonal architecture places domain logic in a core and connects external systems through explicit ports and replaceable adapters.

Where does it come from?

Alistair Cockburn described the approach as Hexagonal Architecture or Ports and Adapters to decouple domain logic from user interfaces and technical resources. It follows the line of abstraction, information hiding, and testable domain logic.

The mental model

Picture a core with several doors: ports define what the core offers or expects; adapters translate each outside world. The domain logic knows the doors, not the building behind them.

Key building blocks

Port

A defined interface at the boundary of the core.

Adapter

An implementation that connects an outside system to a port.

Core

The area containing application-relevant rules and logic.

When is it useful?

Hexagonal architecture makes testing and replacing databases, UIs, or integrations easier. It needs meaningful boundaries; artificial ports and adapters add complexity without useful decoupling.

Alistair Cockburn Ports and Adapters Martin Fowler Hexagonal Architecture Robert C. Martin Clean Architecture