code: @Override
      public OutputStream receiveUpload(String filename,
              String MIMEType) {
          FileOutputStream fos; // Output stream to write to
          try {
              file = File.createTempFile("upload",
                      filename.substring(filename.lastIndexOf('.')));
              // Open the file for writing.
              fos = new FileOutputStream(getFile());
          } catch (FileNotFoundException ex) {
              // Error while opening the file. Not reported here.
              LOG.log(Level.SEVERE, null, ex);
              return null;
          } catch (IOException ex) {
              // Error while opening the file. Not reported here.
              LOG.log(Level.SEVERE, null, ex);
              return null;
          }
          return fos; // Return the output stream to write to
      }
docs: Callback method to begin receiving the upload.