DDD中的工厂，服务，存储库

Question

我对 DDD 中的工厂，存储库和服务有一些疑问。我有以下实体：文件夹，文件，FileData。

在我看来，“文件夹”是聚合根，应该负责创建File和FileData对象。

所以我的第一个问题是我应该使用工厂来创建此聚合，还是由存储库决定？这时我有2个存储库，一个用于Folder，另一个用于File，但在我看来，我应该将它们合并在一起。以下代码段显示了我的文件夹存储库，它位于我的基础架构层中：

public class FolderRepository : IFolderRepository
{
    #region Fields

    private readonly IFolderContext _context;
    private readonly IUnitOfWork _unitOfWork;

    #endregion

    #region Constructor

    public FolderRepository(IUnitOfWork unitOfWork)
    {
        _unitOfWork = unitOfWork;
        _context = _unitOfWork.Context as IFolderContext;
    }

    #endregion

    public IUnitOfWork UnitOfWork
    {
        get { return _unitOfWork; }
    }

    public IQueryable<Folder> All
    {
        get { return _context.Folders; }
    }

    public Folder Find(Guid id)
    {
        return _context.Folders.Find(id);
    }

    public void InsertGraph(Folder entity)
    {
        _context.Folders.Add(entity);
    }

    public void InsertOrUpdate(Folder entity)
    {
        if (entity.Id == Guid.Empty)
        {
            _context.SetAdd(entity);
        }
        else
        {
            _context.SetModified(entity);
        }
    }

    public bool Delete(Guid id)
    {
        var folder = this.Find(id) ?? _context.Folders.Find(id);
        _context.Folders.Remove(folder);

        return folder == null;
    }

    public int AmountOfFilesIncluded(Folder folder)
    {
        throw new NotImplementedException();
        //return folder.Files.Count();
    }

    public void Dispose()
    {
        _context.Dispose();
    }
}

接下来，我在应用程序层中创建了一项服务，这称为“IoService”。我怀疑服务的位置。是应该将其移至域层？

public class IoService : IIoService
{
    #region Fields

    private readonly IFolderRepository _folderRepository;
    private readonly IFileRepository _fileRepository;
    private readonly IUserReferenceRepository _userReferenceRepository;

    #endregion

    #region Constructor

    public IoService(IFolderRepository folderRepository, IFileRepository fileRepository, IUserReferenceRepository userReferenceRepository)
    {
        if(folderRepository == null)
            throw new NullReferenceException("folderRepository");
        if(fileRepository == null)
            throw new NullReferenceException("fileRepository");
        if (userReferenceRepository == null)
            throw new NullReferenceException("userReferenceRepository");

        _folderRepository = folderRepository;
        _fileRepository = fileRepository;
        _userReferenceRepository = userReferenceRepository;
    }

    #endregion

    #region Folder Methods

    /// <summary>
    /// Create a new 'Folder'
    /// </summary>
    /// <param name="userReference"></param>
    /// <param name="name"></param>
    /// <param name="parentFolder"></param>
    /// <param name="userIds">The given users represent who have access to the folder</param>
    /// <param name="keywords"></param>
    /// <param name="share"></param>
    public void AddFolder(UserReference userReference, string name, Folder parentFolder = null, IList<Guid> userIds = null, IEnumerable<string> keywords = null, bool share = false)
    {
        var userReferenceList = new List<UserReference> { userReference };

        if (userIds != null && userIds.Any())
        {
            userReferenceList.AddRange(userIds.Select(id => _userReferenceRepository.Find(id)));
        }

        var folder = new Folder
        {
            Name = name,
            ParentFolder = parentFolder,
            Shared = share,
            Deleted = false,
            CreatedBy = userReference,
            UserReferences = userReferenceList
        };

        if (keywords != null)
        {
            folder.Keywords = keywords.Select(keyword =>
                new Keyword
                {
                    Folder = folder,
                    Type = "web",
                    Value = keyword,
                }).ToList();
        }

        //insert into repository
        _folderRepository.InsertOrUpdate(folder);

        //save
        _folderRepository.UnitOfWork.Save();
    }

    /// <summary>
    /// Get 'Folder' by it's id
    /// </summary>
    /// <param name="id"></param>
    /// <returns></returns>
    public Folder GetFolder(Guid id)
    {
        return _folderRepository.Find(id);
    }

    #endregion

    #region File Methods

    /// <summary>
    /// Add a new 'File'
    /// </summary>
    /// <param name="userReference"></param>
    /// <param name="folder"></param>
    /// <param name="data"></param>
    /// <param name="name"></param>
    /// <param name="title"></param>
    /// <param name="keywords"></param>
    /// <param name="shared"></param>
    public void AddFile(UserReference userReference, Folder folder, FileData data, string name, string title = "", IEnumerable<string> keywords = null, bool shared = false)
    {
        var file = new File
        {
            Name = name,
            Folder = folder,
            FileData = data,
            CreatedBy = userReference,
            Type = data.Type
        };

        if (keywords != null)
        {
            file.Keywords = keywords.Select(keyword =>
                new Keyword
                {
                    File = file,
                    Type = "web",
                    Value = keyword,
                }).ToList();
        }

        folder.Files.Add(file);
        folder.Updated = DateTime.UtcNow;

        _folderRepository.InsertOrUpdate(folder);

        //save
        _folderRepository.UnitOfWork.Save();
    }

    /// <summary>
    /// Get 'File' by it's id
    /// </summary>
    /// <param name="id"></param>
    /// <returns></returns>
    public File GetFile(Guid id)
    {
        return _fileRepository.Find(id);
    }

    #endregion
}

总结一下： 我应该使用该服务来创建文件夹对象。或者服务应该只使用工厂，它负责创建对象并将创建的对象发送到存储库？那么服务中的依赖注入怎么样，我应该从UI层注入我的服务和IOC容器，比如 Unity ，还是我应该硬编码服务中的依赖项？

由于