Sovelluslogiikka

Sovelluslogiikka (application logic) refers to the portion of software responsible for coordinating tasks required to fulfill user interactions. It sits between the presentation layer (user interface) and the domain and data layers, and is responsible for orchestrating use cases, enforcing workflow, and managing cross-cutting concerns.

In practice, sovelluslogiikka is implemented as the service layer or application layer of an architecture. Its responsibilities include validating inputs, enforcing authorization checks, sequencing calls to domain services or repositories, and shaping data for presentation. It does not usually contain the core business rules themselves; those belong to the domain model, but it invokes domain logic and persists state as needed.

Common patterns include the service layer (application services or use-case controllers) and orchestrators that coordinate multiple domain operations. In some designs, a rules engine or workflow engine may be used to manage complex processes within the application logic.

Testing focuses on the orchestration behavior: that given a use case, the correct domain services are called in the right order, that errors are handled gracefully, and that transactional boundaries are respected.

Sovelluslogiikka should be kept separate from the presentation layer and the domain model to preserve separation of concerns, testability, and maintainability. It is a flexible concept that adapts across architectures, including layered, hexagonal, or clean architecture, where the emphasis is on clear responsibilities and minimal coupling between layers.