private void doFilterHibernate(ServletRequest request, ServletResponse response, FilterChain chain)
         throws IOException, ServletException {
      // before processing filter chain:
      // create a hibernate session and open a jdbc connection
      // (in some cases, jdbc connections may not be needed:
      // switch lazyDatabase to true)
      try {
         HibernateUtil.getInstance().createSession();
         if (!lazyDatabase)
            HibernateUtil.getInstance().currentSession();
      } catch (DatabaseException e) {
         LOG.fatal("Error creating hibernate session", e);
      }
      try {
         // process filter chain
         chain.doFilter(request, response);
      } finally {
         // after processing filter chain:
         // close the current hibernate session
         // (an underlying jdbc connection will be closed as well
         // if it has been opened)
         try {
            HibernateUtil.getInstance().closeSession();
         } catch (DatabaseException e) {
            LOG.fatal("Error closing hibernate session", e);
         }
      }
   }

   /**
    * Processes the filtering for http requests. If configured,
    * further filtering is synchronized according to the current session.
    * That means that, for one user (represented through a http session) only
    * one http request is processed at the same time.
    *
    * Only one jdbc connection can be open per user if synchronized.
    *
    * @param request A HttpServletRequest containing the session that is to be synchronized.
    * @param response The HttpServletResponse object.
    * @param chain The FilterChain object.
    * @throws IOException
    * @throws ServletException
    */
   public void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException,
         ServletException {
      if (synchronizeUserSession) {
         HttpSession session = request.getSession();
         synchronized(session) {
            doFilterHibernate(request, response, chain);
         }
      } else {
         doFilterHibernate(request, response, chain);
      }
   }

   /* (non-Javadoc)
    * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
    */
   public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
         ServletException {
      // no synchronization needed as no http session exists
      doFilterHibernate(request, response, chain);
   }