ASP.NET Core MVC Interview Question #131

What is the service layer pattern in an MVC application?

Dependency Injection, Services, Error Handling, Logging & Performance Senior Advanced

Quick Interview Answer

A service layer provides application operations that coordinate business rules, persistence, and other dependencies outside controllers. For example, ProductService might implement create, update, search, or pricing workflows while the controller handles HTTP concerns.

Detailed Explanation

A service layer should add meaningful application behavior rather than merely becoming a one-to-one wrapper around every repository call. Its boundaries should reflect use cases and business capabilities.

Code Example

public interface IProductService
{
    Task<ProductDetailsViewModel?> GetAsync(
        int id,
        CancellationToken token);

    Task CreateAsync(
        ProductInputModel model,
        CancellationToken token);
}