Filestash [1] was born after the infamous FTP top answer on the Dropbox launch [2]. Trying to understand why we couldn't have nice things made on top of FTP, I came out with this interface:

  type IBackend interface {
    Ls(path string) ([]os.FileInfo, error)
    Cat(path string) (io.ReadCloser, error)
    Mkdir(path string) error
    Rm(path string) error
    Mv(from string, to string) error
    Save(path string, file io.Reader) error
    Touch(path string) error
  }

and once I had the UI working nice for FTP, I made it work for every possible file transfer protocol: S3, SFTP, NFS, SMB, WebDAV, Dropbox, Google Drive, .....

[1] https://github.com/mickael-kerjean/filestash

[2] https://news.ycombinator.com/item?id=8863