In the previous issue of Java Jazz Up, you have read about the JAXP APIs and learned how an XML document is parsed using the serially access mode (SAX) parser. Now you will learn how the DOM parser works with the same xml document. Lets quickly focus on the overview
of XML parser.

Introduction to XML Parser:

In computing terms, a parser is a program that takes input in the form of sequential instructions, tags, or some other defined sequence of tokens, and breaks them up into
easily manageable parts. XML parser is used to read, update, create and manipulate an XML document. Whenever the XML document executes, the parser recognizes and responds to each XML structure taking
some specified action based on the structure type.

XML parsers can be validating or nonvalidating. Validating parser checks the contents of a document against a set of specific rules i.e. in what order they must appear. These rules appear in an XML document either as an optional XML structure called a document type definition,
or DTD, or as an XML Schema.

Nonvalidating parsers are smaller and faster, but they do not check documents against the DTD. They only check whether the XML document is structurally well formed or not. Parsing XML Documents

To manipulate an XML document, XML parser is needed. The parser loads the document into the computer’s memory. Once the document is loaded, its data can be manipulated using the appropriate parser.

In this section, we will discuss about DOM parsers of JAXP APIs and for accessing XML documents in random access mode. The specifications to ensure the validity of XML documents are DTDs and the Schemas.

DOM (Document Object Model)

The XML Document Object Model (XML DOM) defines a standard way to access and manipulate XML documents using any programming language (and a parser for that
language).