Validating vs non validating parsers with xml
XML validation is the process of checking a document written in XML (e Xtensible Markup Language) to confirm that it is both well-formed and also "valid" in that it follows a defined structure.
Now that you know how to make use of an XML Schema definition, we'll turn our attention to the kinds of errors you can see when the application is validating its incoming data. Since you don't have one yet, it's value is "null".
For now, think of these attributes as the "magic incantation" you use to validate a simple XML file that doesn't use them.
Once you've learned more about namespaces, you'll see how to use XML Schema to validate complex documents that use them.
Validating parsers perform more rigorous checks, such as making sure the document conforms to the rules laid out by its document type definition (DTD).
Validating parsers also can use information from the DTD to provide extra capabilities, such as entity substitution and attribute defaulting.