Description
int 
ftp_nb_fget ( resource ftp_stream, resource handle, string remote_file, int mode [, int resumepos] )
   ftp_nb_fget() retrieves a remote file from the FTP 
   server.
  
   The difference between this function and ftp_fget() is 
   that this function retrieves the file asynchronously, so your program can 
   perform other operations while the file is being downloaded.