server might not be accessible, or there may be insufficient memory or disk
 storage to handle requests. A system administrator may need to take corrective action.

 <p>
 Servlet containers can safely treat both types of unavailable exceptions in the same way. However, treating temporary
 unavailability effectively makes the servlet container more robust. Specifically, the servlet container might block
 requests to the servlet or filter for a period of time suggested by the exception, rather than rejecting 