New session id from tomcat

Question

I have .jsp page.I use tomcat server .When session is valid and i print sessionid in jsp using function session.getId() it print session id but when session is expire then new session id is printed .I didn't understand why this behavior.I set session timeout to 5 sec fro debugging perpose .what i expect is
that session becomes null.My code is
<%     
     UserData ud=null;
     if(session == null){
     }else{
          if(session != null){
               out.println("BEFORE :" + session.getId() + "<BR>");
               //ud=(UserData) session.getAttribute("ClientObject");
               out.println("AFTER :" + session.getId() + "<BR>");
          if(ud == null){
               //response.sendRedirect("../ServletLogout");
               //response.sendRedirect("www.google.com");
               out.println("UD==NULL" + session.getId() + "<BR>");
     out.println("Welcome to tracking page");
%>
Thanks
Vijay

Answer 1

I imagine that /test and /TestSession/test/test.jsp fall under different web app context paths.
When the Servlet container creates a JSESSIONID cookie to track the session, it includes a path attribute. The path attribute controls in which requests the browser will send the cookie. By default, the path attribute is set to the web app context path. If the context path is /TestSession, the path attribute will be set to /TestSession and the browser won't include the cookie when it makes requests to /test.
You can override the cookie path with a sun-web.xml deployment descriptor:
<sun-web-app>
  <session-config>
    <cookie-properties>
      <property name="cookiePath" value="/"/>
    </cookie-properties>
  </session-config>
</sun-web-app>You could also rewrite the outbound Set-cookie: header with an Output directive in obj.conf.
A simpler, less brittle solution would be to redirect requests for /test instead of restarting them.