Glossary

Hexagonal Architecture

Hexagonal Architecture (Ports & Adapters, Alistair Cockburn) — domain logic at the centre, isolated from the outside world through ports (interfaces) and adapters (implementations). HTTP, queues, databases, CLI — all external and interchangeable.

Ports and adapters

Port — an interface describing interaction with the domain. E.g.: UserRepository, PaymentGateway
Primary adapter — initiates an action (HTTP controller, CLI command, queue consumer)
Secondary adapter — implements a port (MySQL repository, Stripe gateway, SendGrid mailer)

Why "hexagon"

The hexagon in the name is not a technical fact but a symbol: the domain has several sides (ports) for external interaction. The number is not fixed.

Related concepts

Clean Architecture, Onion Architecture — different names for the same idea: business logic does not depend on infrastructure. The difference is in layering details.