As I’ve pointed out, Books is an application that’s maintained by just one author, who should know about the expected data. So there’s no user interface that gives an immediate response after each input or that offers lots of hints. Of course, those features are essential for an application intended for potentially unknown users. Later on, when developing a second application called Alumni , I’ll cover those features in detail. Right now, validation will be useful in preventing a user from entering data that might not fit the database.
Remember the JSF lifecycle ...
