What are the advantages and disadvantages of using a common interface for remote and local data sources?

Using a common interface for remote and local data sources has its advantages and disadvantages.

Advantages:

• Simplified architecture: client code works with a single interface, without worrying about where the data comes from.
• Ease of replacing data sources: you can switch between local and remote sources without changing business logic.
• Increased testability: data sources can be replaced with mock objects.

Disadvantages:

• Differences in behavior and performance: remote sources may be slower, have network errors, which requires additional handling.
• Error handling complexity: local sources are usually reliable, but remote ones are not, which can complicate logic.
• Differences in data model or format: sometimes local and remote data have different structures, requiring adaptation.

Example: the DataSource interface with getData() methods, implemented by LocalDataSource and RemoteDataSource classes. Client code calls getData() without knowing exactly where the data comes from.