public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
		// client browser will request the page every 60 seconds
		HttpSession session = request.getSession();
		Long times = (Long) session.getAttribute("times");
		if (times == null) {
			session.setAttribute("times", new Long(0));
		}
		long temp = 1;
		if (times != null) {
			temp = (times.longValue()) + 1;
		}
		if(temp<5){
			response.addHeader("Refresh", "15");
		}
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out.println("<html><head><title>Client Refresh</title></head><body>");
		out.println("You've viewed this page " + temp + " times.");
		session.setAttribute("times", new Long(temp));
		out.println("</body></html>");
	}