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Table of Contents

Introduction Where does XML come from? How does XML work? Business integration with XML XML, Browsers and RDF What XML will help to achieve

XML for Not Yet Techies

By Richard Stooker, Info Ring Press

Introduction

XML stands for Extensible Markup Language and was approved by the World Wide Web Consortium (W3C) in February 1998. Computer careers in it are just beginning.

XML is the foundation for a whole new way of communicating across the Internet, and even beyond.

So what does that mean? And why should you care? Let's say it's a few years from now.

1. You log on to the Internet to look up the phone number of a friend in Shanghai. The telephone directory web site offers you the choice to view the directory in 20 different major languages. You pick English. When your (Chinese) friend in Shanghai logs on to the same telephone directory web site to look up your phone number, he picks Mainland Chinese characters.

2. While you're traveling on a sales call, your boss looks up data on the company, which is your prospect, which is stored on your company's intranet. He sends you the report to read. Although it's 200 pages long, you are easily able to pick out the information, which you feel is relevant, and read it -- on your cell phone. When you're finished, you relax in your hotel room by watching a movie, which you selected by feeding the words "latest" and "action" into the TV's search engine.

3. You get the contract. You call in the specifications. Two engineers begin work on the project. One reads the specs as most people do. The other reads them in Braille, since she's blind.

What makes these scenarios - and many others that are presently beyond our imaginations - possible, is XML. 

Where does XML come from?

How could information take so many different forms? Different languages, different machines . . . XML is going to radically change the way we relate to "information."

OK, let me try to explain from the top. The publishing industry has been concerned for many years with standards for presenting documents. Of course, that's their business. They have used what's called the Standard General Markup Language (SGML) for many years now.

When the World Wide Web came along, someone pulled pieces of SGML and put them together to design web pages, and that's how HTML (HyperText Markup Language) was born. It's sort of a child of SGML.

Now, HTML is good at telling web browsers how to display text and other parts of a web pages. And of course it also has hypertext links. That's its job. But as the Internet has advanced, many people have clamored for more than that.

Dynamic HTML (DHTML) goes a long way toward making web sites that are more interesting and interactive, but XML is a big step beyond that.

XML is not really a new language, it's a meta-language. It's a system for defining other languages. It's for creating documents that are so structured that they are smarter than the average web site.

How does XML work?

Extensible Markup Language is about embedding the structure and classification system of information inside the document itself. Extensible Markup Language is a way for the document to carry information about itself. Documents will describe the information they contain. Now, "documents" are markings on paper or electrons on screen. We supply the intelligence.

Extensible Markup Language contains its own intelligence, which will help to maximize our use of our intelligence.

For example, if you know HTML or have seen it, you know that the way to tell a web browser to begin a new paragraph is with a "<p>" symbol placed inside the document right where you want the new paragraph to start. That "<p>" tells the browser to start a new paragraph. It does not tell the browser or the reader what the paragraph is about.

What if you could put tags into a sentence such as this: <moviestar>Drew Barrymore</moviestar> waved to the cameras. Or: <author>Drew Barrymore</> autographed her latest book.

Anybody with the least familiarity with HTML can recognize the tag structure. But <moviestar> and <author> are not standard HTML tags. Today's browsers would ignore them.

The second sentence tells the browser of the not too distant future that it is not referring to the Drew Barrymore who is a movie star, but the one who has written books. They are the same person of course, but they are two different aspects of her. The <moviestar> tags could be further subdivided into different parts of her career, say as a child in ET or as an adult, or even into individual movies.

So what, you say? You knew that already. Yes, you as a human being could read those two sentences without the tags and, knowing who Drew Barrymore is, understand. But your browser can't, yet. Soon, it will.

And what are the practical on the computer job advantages to this? What if you want to search the web for information on her first book. If you put "Drew Barrymore" in a search engine now you will get hundreds of thousands if not millions of entries. Many will concern her movie career. Some links might be about the Drew Barrymore who works at the HITech Co's research lab. I made that up, but when you search even for famous people it's not unusual to get hits for many different people.

But if you tell the search engine to look only for the "<author> tagged "Drew Barrymore"s, you will be much more successful.

In a few years, Internet newbies will not believe us when we tell them that search engines used to return thousands of sites for simple searches.

The beauty ofExtensible Markup Language is that you can define your own tags.

That sounds like anarchy, I know. How can we get away with it? You structure how your document's information is classified, as well as how it's presented. (HTML is not going to go away.) That is what the "extensible" part means. You can extend it as far as you want to take it.

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