title: validation before rendering page
body: <p>I'm new to JSF and using JSF2 to build a webapp which has several pages. I'm using a session scoped bean to keep some parameters that were set by going through the different pages. </p>
  
  <p>When the session times out (or I redeploy the app) and I go to a specific page then this page is not able to render correctly because some data is missing from the session. At this point I want the home page to be shown.</p>
  
  <p>I want to use this mechanism for all pages. So in general I want to do some validation before rendering a page and direct the user to the home page if the validation fails.</p>
  
  <p>How should I handle this?</p>