code: public void write(byte []buf, int offset, int length, boolean isEnd)
      throws IOException
    {
      OutputStream os = _os;
      
      if (os != null) {
        os.write(buf, offset, length);
      }
    }
docs: Writes a buffer to the underlying stream.
  
  @param buffer the byte array to write.
  @param offset the offset into the byte array.
  @param length the number of bytes to write.
  @param isEnd true when the write is flushing a close.