Third Tutorial--Let there be XML!

Third Tutorial

The birth of XML and its application

the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters. And God said, Let there be light：and there was light. And God saw the light, that it was good：and God divided the light from the darkness.
Genesis, Bible

At the time when everybody was frustrated with the chaotic webpages, and browser producers and software engineer were exhausted with endless updates, there came a group of men, who said:" No! Wait a minute! " and launched a brand new web standard--XML. The future of the web then had been changed for ever.

So let's see how XML solved the problems HTML had given us. Firstly, according to the standard, XML tag should not contain any style definition. Therefore, the definition of style is seperated from the content. It makes the whole XML fiile clean and tidy. When reading it, you can focus only on the contents for presentation, leaving all those visual design to another people. In addition, the separation of content and design makes it extremely easy to either apply a coherent style to multiple files or change the style of many elements all at the same time. Thus, a lot of manual work is saved.

Secondly, rather than allowing syntax mistakes spreading around in the webpage like HTML is doing, XML, on the other hand, strictly forbids any misuse of the language. The rules include every tag should be ended correctly, e.g. a <student> tag must be followed by a </student> tag in later coding, and the correct nesting of of tags, etc. Any syntax mistake is not tolerated in XML. If you try, you may see an error statement telling you what's going wrong, conspicuously. The strictness of syntax also entitles XML to be applied to various types of browsers. For many cases, the same XML may be viewed from computers, TV screens, PDAs, and even digital cameras, probably in the same way if it has correct style definition. On the contrary, HTML sometimes even look extremely different among different computers.

Thirdly, XML relieves browser programers from endless updates, and gives page coders full flexibility to program in their webpages. Perhaps it's why it has its name, XML--eXtensible Markup Language. Instead of listening to vast users to decide whether to have a new tag included in the new version of language, XML allows users to define their own tags. It is a marvellous idea since it has ended the arguments of tags theoretically. Of course, if you intend to invent a new tag, you should add some definition to tell the browser what you've added. That is the .DTD file, or to say, the XML schemas. Updates of browsers now seem unnecessary. XML, when giving the web a clear, strict standard of its accessibility, also brings us great flexibility in our own charge.

Generally speaking, XML is not an language but actually a standard. Scientists begin to apply XML into various kind of programming, from webpages, to desktop application, to mobilephone, etc. It enlightens people to see a brilliant future of web programming and applications. Let there be XML!

referrence: XHTML--Example by Example

Link: development history of XML