Which layer provides server-side validation logic such as Decisions and Calculators?

Which layer provides server-side validation logic such as Decisions and Calculators?

• A. Front-end components
• B. Database constraints
• C. External service
• D. API modules

Answer: (D)

API modules provide the server-side layer for validation logic like Decisions and Calculators. These run on the server, so the rules and calculations are applied consistently regardless of the client, which helps protect data integrity and enforce uniform behavior across all entry points. Keeping this logic in the API layer also makes it reusable by different front ends and services, while letting the front end stay lightweight. Front-end components run in the browser and should handle only UI-focused checks; they cannot be trusted for secure validation. Database constraints ensure data integrity at the storage level but aren’t designed to implement complex business rules. External services are for interacting with outside systems, not for centralizing the app’s internal validation.

API modules provide the server-side layer for validation logic like Decisions and Calculators. These run on the server, so the rules and calculations are applied consistently regardless of the client, which helps protect data integrity and enforce uniform behavior across all entry points. Keeping this logic in the API layer also makes it reusable by different front ends and services, while letting the front end stay lightweight. Front-end components run in the browser and should handle only UI-focused checks; they cannot be trusted for secure validation. Database constraints ensure data integrity at the storage level but aren’t designed to implement complex business rules. External services are for interacting with outside systems, not for centralizing the app’s internal validation.