Design patterns·The shape of the whole application
the same use case runs from an HTTP handler, a message consumer and a test, and none of them is the primary one.
Hexagonal architecture
Also calledports and adapters, hexagonal, ports & adapters
An arrangement where the application defines ports — interfaces for what it needs and what it offers — and adapters implement them for HTTP, databases, queues or tests. The hexagon shape carries no meaning beyond having several sides; the content is that the application never depends on a delivery mechanism or a storage technology. It makes the application testable in isolation and adds an interface plus an adapter for every boundary, which is real work for a small service.