In Clean Architecture, use cases are a central concept that encapsulate the business logic of an application. They represent specific tasks or operations that the system needs to perform, focusing on the business rules and processes rather than the technical implementation details. Here’s a detailed explanation:
Definition and Purpose
A use case in Clean Architecture is a piece of business logic that defines a single task the system must perform. It encapsulates the rules and logic required to achieve a specific goal, ensuring that the business logic is separated from other concerns like data access and user interface[2][4][7].
Structure and Placement
Use cases typically reside in the domain layer of the application, which is responsible for representing the business concepts and entities. This layer is isolated from the presentation and data layers, promoting modularity and flexibility. The domain layer defines the use cases and operations that can be performed on business entities, ensuring that the business logic is independent of any specific technology or framework[2][4][6].
Benefits
Modularity: By encapsulating business logic into individual use cases, the system becomes more modular and easier to manage. Each use case has a clear and well-defined purpose, making the code more readable and maintainable[2][6].
Testability: Use cases can be tested independently of other parts of the system, which simplifies the testing process and improves the reliability of the code[2][6].
Reusability: Use cases can be reused across different parts of the system or even in other projects, enhancing overall efficiency and maintainability[2][6].
Flexibility: Changes to business logic can be made within the use case without affecting other parts of the system, making it easier to adapt to changing business requirements[2][6].
Implementation
When implementing use cases in Clean Architecture, each use case is typically represented by a class or function that defines the inputs, outputs, and the business logic required to perform the task. This approach ensures that the business logic is decoupled from the user interface and data access layers, adhering to the Dependency Rule, which states that source code dependencies can only point inward[2][4][6].
Example
Consider an e-commerce application where a use case might be "Process Order". This use case would encapsulate all the business rules related to proce...
