- Launch a very simple JSF app consisting of two pages, as described by the Select example from Chapter 4 of the Core JavaServer Faces book by D. Geary and C. Horstmann (no database calls).
- Allow the session to time out.
- Use your browser's back button to return to the index.faces page.
- Re-submit the form.
- Watch the app blow up with this exception:
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: viewId:/index.faces - View /index.faces could not be restored.
javax.faces.webapp.FacesServlet.service(FacesServlet.java:270)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
root cause
javax.faces.application.ViewExpiredException: viewId:/index.faces - View /index.faces could not be restored.
com.sun.faces.lifecycle.RestoreViewPhase.execute(RestoreViewPhase.java:186)
com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:104)
com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
After a lot of research on the web, the following context parameter in the web.xml file resolves it:
<context-param>
<param-name>javax.faces.STATE_SAVING_METHOD</param-name>
<param-value>client</param-value>
</context-param>
To see it in action, set your session timeout to 1 minute in web.xml:
<session-config>
<session-timeout>1</session-timeout>
</session-config>
However, be careful using this setting: You will cause the entire UI component tree to be serialized and passed to the client. This can increase download lag time, especially on more complex layouts. Also, there are times when sessions must expire (authenticated sessions), so you'd want to stick with the server for your state saving method in most cases.
