What is the role and the advantages of using a local data source interface in application architecture?

The interface of a local data source in an application architecture serves as an abstraction for accessing data stored locally (e.g., in a database or files). Its role is to separate the data handling logic from the rest of the application, which allows:

• Easily changing the data source implementation without affecting business logic.
• Simplifying testing by replacing the real source with a mock or stub.
• Improving code readability and maintainability through a clear interaction contract.

For example, the interface may define methods for retrieving, saving, and deleting data, while a specific implementation might use Room, SQLite, or the file system.