LayeringSimple

LayeringSimple is a software design approach that advocates organizing a software system into distinct layers with straightforward, predictable rules for interaction between layers. It aims to provide a lightweight, maintainable structure that supports clear separation of concerns.

The approach emphasizes minimal coupling and inward-directed dependencies. Outer layers may depend on inner layers through well-defined interfaces or adapters, but inner layers should not depend on details from outer layers. LayeringSimple discourages cross-layer calls that bypass intermediate boundaries and discourages leakage of business logic into presentation code.

Common structure includes layers such as Presentation, Service (or Application), Domain, and Data Access. A simple rule is that each layer only relies on the layer immediately below it, mediated by interfaces or adapters.

Implementation practices include defining explicit interfaces, using data transfer objects to cross layer boundaries, and applying adapters or facades to isolate external systems. Dependency inversion and minimalistic contracts are typical guiding principles. Teams often apply unit and integration tests at each layer to verify responsibilities.

Applications of LayeringSimple span many domains, including web applications, mobile apps, and API services. It is particularly suitable when a straightforward, maintainable separation of concerns is desired. Limitations include potential boilerplate, over-division leading to unnecessary complexity, and performance concerns if the boundaries are not judiciously managed.

Related concepts include layered architecture, clean architecture, and hexagonal architecture.