Chapter 1: XML Overview: The Big Picture

XML Overview: The Big Picture

What's Wrong with HTML?

HTML has proven effective for information sharing over the internet. However, its limitations are starting to be felt:

Poor separation of content and format. Much markup is actually rendering information.
Cumbersome for representing specialized, structured documents.
Lacks features for processing information automatically.

The web is ready for its next-generation markup language.

Advantages of XML

It offers strict separation between content and format.
You can produce different formats from the same document.
It is highly structured, thus enables powerful automatic manipulation of data.
CambridgeDocs explains these advantages in a succinct white paper, Why Create/Convert Documents to XML?

So What Is XML?

XML (eXtensible Markup Language) is not a markup language. It is a metalanguage, i.e. a syntax for describing markup languages.
It enables you to create markup languages specific to an industry or application.
It is based on the SGML standard (Standard Generalized Markup Language).

It provides a standardized way for different applications in different locations to share data.

Current W3C XML Recommendations
Standard Abbreviation Specification Status Purpose

XML XML Recommendation XML Specification

XML Namespaces XML-NS Recommendation Prevent name conflicts

XML Linking Language XLink Candidate Recommendation Document linking

XML Path Language XPath Recommendation Addressing parts of a document

XML Stylesheet Language XSL Working Draft Document presentation

XSL Transformation XSLT Recommendation Data modification

XML Schema Candidate Recommendation Improved DTDs

**Current W3C XML Recommendations**
Standard	Abbreviation	Specification Status	Purpose
XML	XML	Recommendation	XML Specification
XML Namespaces	XML-NS	Recommendation	Prevent name conflicts
XML Linking Language	XLink	Candidate Recommendation	Document linking
XML Path Language	XPath	Recommendation	Addressing parts of a document
XML Stylesheet Language	XSL	Working Draft	Document presentation
XSL Transformation	XSLT	Recommendation	Data modification
XML Schema		Candidate Recommendation	Improved DTDs

Internet Explorer Support

Today, the only browser that supports XML is IE (5.0 and above).

IE5 doesn't yet support the latest standards:

Standards Supported by IE5
Standard Version Supported

XML XML 1.0 - Second Edition (Latest Version)

XLink Not Supported

XSL Limited version of the 16 Dec 98 Working Draft

Schemas 5 Jan 98 Note

**Standards Supported by IE5**
Standard	Version Supported
XML	XML 1.0 - Second Edition (Latest Version)
XLink	Not Supported
XSL	Limited version of the 16 Dec 98 Working Draft
Schemas	5 Jan 98 Note

What this course uses:

XML 1.0 Second Edition (latest Recommendation)
Namespaces: 14 Jan 99 Recommendation (latest Recommendation)
Schemas: 5 Jan 98 Note (version supported by IE5)
XSL: 18 Oct 00 Working Draft (latest Working Draft)
XLink 3 Mar 98 Working Draft
XPath 9 July 99 Working Draft