1. lv2ftp isn's serious, just a test and benchmark of the sntllv2
2. there are few stages:
2.1 Simple v.1
    This protocol is enough to donwload a directory subtree with files.
2.1.1 Directory workout
    * Open directory stream: (dir-open "<dir-name>")
      * Return: error, or rapidly replies with (dir-stream <id>)
    * Read directory entry: (dir-read <id>)
      * Return: error, or rapidly replies with the following:
        * (dir-end <id>)
        * (dir-entry "<filename>" "<filetype>"), where filetype the following:
          * regular - regular file
          * directory - directory
          * block - block device
          * char - char device
          * fifo - named pipe
          * link - symbolic link
          * socket - socket
          * unknown - unknown file type
     * Close directory entry: (dir-close <id>)
       * Return: error or SNE_SUCCESS
2.1.2 File workout
     * Open file: (file-open "<file-name>")
       * Return: error, or rapidly replies with (file-id <id>)
     * Get simple stat: (file-stat <id>)
       * Return error, or rapidle replies with (file-stat <id> <size>)
     * Read file data: (file-read <id> <offset>)
       * Return error, or rapidly replies with 30k(raw data, in base64 it will be more) (file-data <id> <offset> "<B64encoded data>")
     * Close file: (file-close <id>)
       * Return error or SNE_SUCCESS