using System; namespace Model { public interface ILibraryManager { Task GetBookById(string id); Task GetBookByISBN(string isbn); Task>> GetBooksByTitle( string title, int index, int count, string sort = "" ); Task>> GetBooksByAuthorId( string authorId, int index, int count, string sort = "" ); Task>> GetBooksByAuthor( string author, int index, int count, string sort = "" ); Task GetAuthorById(string id); Task>> GetAuthorsByName( string substring, int index, int count, string sort = "" ); } }