put the name of servlet in wondow.open function which is registered in your web.xml then use your servlet like this
String date=code for date;
RequestDispatcher rd = request.getRequestDispatcher("./JspPageName");//your jsp page name as registered in your web.xml file
then use this date varibale in jsp for retriving date value.
Please friends if you find anything wrong in this please let me know...Thanks a lot.