For those reasons, developers who are writing a user-oriented application that displays an XML document and possibly modifies it will want to use the DOM mechanism described in Chapter 3, Document Object Model.
However, even if you plan to build DOM applications exclusively, there are several important reasons for familiarizing yourself with the SAX model: It is helpful to understand the SAX event model when you want to convert existing data to XML.
So if the application does not generate an exception, then the default error-event handler generates one.
But for nonfatal errors and warnings, exceptions are never generated by the default error handler, and no messages are displayed.
In general, such parsers work well when you simply want to read data and have the application act on it.The parser can generate three kinds of errors: a fatal error, an error, and a warning.