DevGuru XML DOM Introduction

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Welcome to the XMLDOM Quick Reference guide. This is a valuable 239 page reference detailing all the interfaces deemed by W3C to be basic to any implementation of the DOM (including HTML), as well as XML-specific interfaces and Microsoft's own, further extensions to the Document Object Model. Each object is fully described with working examples that clearly illustrate how its properties and methods (and in the case of Microsoft's extension, event handlers) can be used to manipulate actual XML documents.

For an introduction to XML, please read the tutorial:
A Beginners Guide to Creating and Displaying Your First XML Document.

XML was developed by the W3C between 1996 and 1998 to provide a universal format for describing structured documents and data; in other words, it allows data to be self-describing. It is basically a simplified subset of the Standard Generalized Markup Language. SGML was designed back in 1986 as a metalanguage to describe other languages, and XML was to enable generic SGML to be processed on the web in much the same way as is currently the case with HTML.

XML describes a class of data objects called XML documents and the XMLDOM provides you, the programmer, with the means to manipulate them through code, either on web pages or in applications. The nesting of tags creates a tree-like structure which means that the handling of these documents is greatly simplified, as the examples in this Quick Reference clearly demonstrate.

One of XML's great advantages is that it allows the creation of a markup language from scratch, meaning that different industries and professions can develop custom languages that accurately handle their industry-specific data. This is well reflected in the recent proliferation of new markups ending in 'ML' such as Wireless Markup Language, Chemical Markup Language, Speech Synthesis Markup Language, Gene Expression Markup Language, and the not-to-be-taken-seriously Mind Reading Markup Language.

In the past two years since XML's completion, it has been adopted across the board with great enthusiasm in the anticipation that it will herald the dawn of a new era in information and document exchange over the internet (in fact, the next version of HTML is expected to be an XML application). Its advocates are confident that XML will provide greater flexibility in transfering data between different applications on different platforms and machines, and greatly increase the accuracy of web searches. Add to that the fact that its reliance on Unicode makes it international and this enthusiasm is easy to understand.

The DOM Structure Model
Level 1 of the Document Object Model (Core) represents documents as a hierarchy of Node objects. (This applies to HTML as well as XML documents.) Some of these Node objects may have child nodes of various types, while others are 'leaf' nodes which can have nothing below them. These Node objects and any child nodes they may have are listed below.

Attr
Text, EntityReference
CDATASection
No Children
Comment
No Children
Document
Element, ProcessingInstruction, Comment, DocumentType
DocumentFragment
Element, ProcessingInstruction, Comment, Text, CDATASection,
EntityReference
DocumentType
No Children
Element
Element, ProcessingInstruction, Comment, Text, CDATASection,
EntityReference
Entity
Element, ProcessingInstruction, Comment, Text, CDATASection,
EntityReference
EntityReference
Element, ProcessingInstruction, Comment, Text, CDATASection,
EntityReference
Notation
No Children
ProcessingInstruction
No Children
Text
No Children

Fundamental Interfaces
The following interfaces are considered fundamental and, as such, must be included in any conforming implementation of the DOM, including HTML implementations.

Extended Interfaces
The following interfaces, while forming part of the DOM Level 1 Core specification, are not required by a purely HTML implementation of the DOM, as there are no objects to expose them, but they do form part of an XML implementation.

Microsoft Interfaces
The following interfaces are Microsoft extensions to the W3C DOM.