Servlet waiting page, processes, then redirecting to completed page

i have a form on a jsp (lets call it formjsp.jsp)... this form will call a servlet... the problem is that this servlet will take a long time to process... therefore, i want some indicator (something like a window, doesnt have to be a popup, it can just go to that new page called waiting.jsp) that tells the user to wait and not touch anything...

however, heres the tricky part, after the servlet is finished, i need it to redirect to the completed page (call it complete.jsp)... so if waiting.jsp was a popup, i'd like to close the popup... if waiting.jsp was a page on the original browser window, i want it to redirect to complete.jsp... does that make sense?

i have tried to do both page calls within the servlet, so i would have:
//SERVLET
public void doPost ... {
    RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("waiting.jsp");
    dispatcher.include(request, response);

    //do long processing

    RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("complete.jsp");
    dispatcher.forward(request, response);
    //btw, i have also tried >> response.sendRedirect("complete.jsp"); but neither of them work
}


another way ive thought of has been to forward directly to waiting.jsp and then make it forward a hidden submission to the servlet, which then redirects to complete.jsp when it is done... however, im not quite sure how to do this hidden submission (is there any other way besides using http-equiv?) and i also do not know how to forward the POST parameters.


if anyone has any elegant ways of accomplishing what i want, please suggest them

btw, i really do not wish to use javascript

thanks so much!