code: @Override
      public void doGet(HttpServletRequest req, HttpServletResponse res)
              throws IOException {
          String source = req.getParameter("source");
          String style = req.getParameter("style");
          String clear = req.getParameter("clear-stylesheet-cache");
  
          if (clear != null && clear.equals("yes")) {
              m_cache.remove(style);
          }
  
          try {
              apply(style, source, req, res);
          } catch (Exception e) {
              res.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e
                      .getMessage());
              e.printStackTrace();
          }
      }
docs: Accept a GET request and produce a response. HTTP Request Parameters:
  <ul>
  <li>source - URL of source document</li>
  <li>style - URL of stylesheet</li>
  <li>clear-stylesheet-cache - if set to yes, empties the cache before
  running.
  </ul>
  
  @param req
  The HTTP request
  @param res
  The HTTP response