title: Tomcat session expired handling
body: <p>I have a question about session in Tomcat.</p>
  
  <p>When Tomcat default session expired time is 30 min I know.</p>
  
  <p>I want to show session expired message page to users.</p>
  
  <p>How can I handle it?</p>
  
  <p>If session expired error code is exists, please guide to me.</p>
  
  <p>I googled about session expired error code, but I couldn't found it.</p>
  
  <p>please teach me your way.</p>