code: @Override
      public String beginFileUpload() throws TException {
          String fileLoc = null;
          try {
              String path;
              String key = UUID.randomUUID().toString();
              path = StormConfig.masterInbox(conf) + "/" + key;
              FileUtils.forceMkdir(new File(path));
              FileUtils.cleanDirectory(new File(path));
              fileLoc = path + "/stormjar-" + key + ".jar";
  
              data.getUploaders().put(fileLoc, Channels.newChannel(new FileOutputStream(fileLoc)));
              LOG.info("Begin upload file from client to " + fileLoc);
              return path;
          } catch (FileNotFoundException e) {
              LOG.error("File not found: " + fileLoc, e);
              throw new TException(e);
          } catch (IOException e) {
              LOG.error("Upload file error: " + fileLoc, e);
              throw new TException(e);
          }
      }
docs: prepare to upload topology jar, return the file location