Connect Vaadin and HttpServlets

Hello guys,

i work with very old web app (15+ years) that was made using HttpServlets and applet, i replaced applet that work as menu (it has links to different HttpServlets) with Vaadin Tree and works. But now i have problem: when user click node in tree it should redirect certain HttpServlet.
All HttpServlets not registred in web.xml they are called one from another through html tags.
Also i use Vaadin 6 as app deployed on WAS 6.1 where only java 1.5 is possible, so i need solution Vaadin 6.

    tree.addListener(new ItemClickListener() {
        public void itemClick(ItemClickEvent event) {
            if(event.getItemId().equals("Report")) {
                //redirect to HttpServlet 

I tried mad idea: implemented HttpServletRequestListener and in onRequestEnd() redirect to HttpServlet, but that dont work.

Any ideas ?