interactor

An interactor is an entity that participates in an interaction between a user and a system, or, in software architecture, a component that encapsulates the business logic of a use case. It operates independently of the user interface and presentation layers, focusing on data manipulation, rule enforcement, and coordination of tasks required by a specific use case.

In software architecture, the interactor receives a request from a presentation or controller layer, processes the request by applying business rules, and may retrieve or store data via entities or data managers. It then returns results to the caller, typically through callbacks, promises, or delegates. The interactor is designed to be testable and decoupled from UI concerns, enabling reuse across different interfaces and platforms.

A well-known context for interactors is the VIPER architectural pattern, where the Interactor implements the use case logic and communicates with Entities (data models) and data gateways while remaining separate from the View, Presenter, and Router. This separation helps maintain clear boundaries between the business rules and the user interface or navigation logic.

In human–computer interaction contexts, the term interactor can be broader and refer to the participant in an interaction (often the user) or to any device or software module that mediates between user actions and system responses. Interactors can be software routines, hardware controllers, or middleware that translates inputs into meaningful operations within a system.

Overall, the interactor plays a central role in organizing business logic, promoting separation of concerns, and enabling testable, reusable use-case implementations.