The Duke’s Bookstore database access object returns the following exceptions:
BookNotFoundException: Returned if a book can’t be located in the bookstore database. This will occur if you haven’t loaded the bookstore database with data or the server has not been started or has crashed. You can populate the database by running ant create-tables.
BooksNotFoundException: Returned if the bookstore data can’t be retrieved. This will occur if you haven’t loaded the bookstore database with data or if the database server hasn’t been started or it has crashed.
UnavailableException: Returned if a servlet can’t retrieve the web context attribute representing the bookstore. This will occur if the database server hasn’t been started.
Because you have specified an error page, you will see the message
The application is unavailable. Please try later.
If you don’t specify an error page, the web container generates a default page containing the message
A Servlet Exception Has Occurred
and a stack trace that can help you diagnose the cause of the exception. If you use errorpage.html, you will have to look in the server log to determine the cause of the exception.