//--------< send file content each time 512 size >-------
        private bool SendFile(ICommService service, string file)
        {
            long blockSize = 512;

            try
            {
                string filename = Path.GetFileName(file);
                service.OpenFileForWrite(filename);
                FileStream fs        = File.Open(file, FileMode.Open, FileAccess.Read);
                int        bytesRead = 0;
                while (true)
                {
                    long remainder = (int)(fs.Length - fs.Position);
                    if (remainder == 0)
                    {
                        break;
                    }
                    long   size  = Math.Min(blockSize, remainder);
                    byte[] block = new byte[size];
                    bytesRead = fs.Read(block, 0, block.Length);
                    service.WriteFileBlock(block);
                }
                fs.Close();
                service.CloseFile();
                return(true);
            }
            catch (Exception ex)
            {
                Console.Write("\n  can't open {0} for writing - {1}", file, ex.Message);
                return(false);
            }
        }