ApplicationLayer

Development of Domain Logic with implementation. Interfaces drives business requirements and implementations in this layer. Application layer defines that user required actions in app services classes as below way;

public interface IProductAppService
{
    Task<IEnumerable<ProductDto>> GetProductList();
    Task<ProductDto> GetProductById(int productId);
    Task<IEnumerable<ProductDto>> GetProductByName(string productName);
    Task<IEnumerable<ProductDto>> GetProductByCategory(int categoryId);
    Task<ProductDto> Create(ProductDto entityDto);
    Task Update(ProductDto entityDto);
    Task Delete(ProductDto entityDto);
}

Also implementation located same places in order to choose different implementation at runtime when DI bootstrapped.

public class ProductAppService : IProductAppService
{
    private readonly IProductRepository _productRepository;
    private readonly IAppLogger<ProductAppService> _logger;

    public ProductAppService(IProductRepository productRepository, IAppLogger<ProductAppService> logger)
    {
        _productRepository = productRepository ?? throw new ArgumentNullException(nameof(productRepository));
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
    }

    public async Task<IEnumerable<ProductDto>> GetProductList()
    {
        var productList = await _productRepository.GetProductListAsync();
        var mapped = ObjectMapper.Mapper.Map<IEnumerable<ProductDto>>(productList);
        return mapped;
    }
}

In this layer we can add validation , authorization, logging, exception handling etc. -- cross cutting activities should be handled in here.