XML – The universal data format

By : |April 30, 1999 0



XML – The universal data format
eXtensible Markup Language (XML) is a standard for defining data and metadata. In
W3C’s own words, it is “a common syntax for expressing structure in data.”
To make any sense of that, read on!

The Story So Far
Standard Generalized Markup Language (SGML) is an international standard for
creating and using tagged document formats. The key idea is to separate content from
presentation. SGML is not a document language by itself, but only a description of how to
specify one. One such well-known derived format is Hyper Text Markup Language (HTML). XML
is another.

SGML documents were extensible, structured, and could be validated. For the sake
of simplicity, HTML did away with those features. HTML is not extensible; you cannot
define your own tags. Because it has no well-defined structure, it becomes difficult to
extract data from it. Lastly, browsers aren’t very strict about validating HTML
documents. Most of the time they simply ignore syntax errors.

While this has made HTML the lingua franca of the Web, people wanting to share
data have been crippled by the inconsistencies. The WWW Consortium’s effort to
promote XML is an effort to combine SGML’s robustness with HTML’s simplicity.

Getting the weather across the Net
XML looks very much like HTML, until you take a closer look. It provides
features that enable users to share data across networks, especially on the Internet and
on intranets, in a user-defined manner.

Suppose a meteorological office records live weather feeds on their web site.
One way of accessing this data would be using a Web browser. If XML was used to record
this data, it would be in a standardized format, and that makes it more accessible. A TV
station can program its computers to read the data every minute, and broadcast it
immediately on its weather channel. Elsewhere, an aircraft’s onboard computer can
query the site, and display the information on the dashboard. The most important thing
here is that we will no longer be limited by the kind of hardware or software we have, or
by proprietary formats of data recording.

Where is XML now?
Chartware Inc. has made headway in using XML to generate patients’
records using their clinical record keeping software. The main benefit of this system is
that it allows doctors and healthcare groups to arrive at better solutions through
collaboration of data and ideas on the Internet easily and economically. This does away
with the need for a private network.

Microsoft Office 2000 uses XML to store data such as spreadsheet formulae a
document is saved in HTML format for publication on the web or on an intranet. In Office
97, formulae, macros, etc. would have been lost. Also, Internet Explorer uses XML to
recognize the parent software (whether Word, Excel, or PowerPoint) that created the HTML
file in the first place.

At the end of the day…
With a little luck, XML should replace HTML as the standard for the web
when it comes to publishing data. The ability to use a powerful platform-independent
document language over the Internet holds great promise for the future of network
computing.

XML vs. HTML
The key idea behind XML is to separate content from
presentation.

With HTML you cannot define your own tags and people
wanting to share data have been crippled by HTML’s inconsistencies.

The WWW Consortium’s effort to promote XML is an effort to combine
SGML’s robustness with HTML’s simplicity.

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