A SHORT INTRODUCTION TO INTERNET TECHNOLOGYText information and data – XML (Extensible Markup Language)
When the early version of HTML was designed by Tim Berners-Lee at CERN, he based it
on the existing standard for representation of documents. This standard was SGML, the
Standard Generalised Markup Language which was ratified by the ISO in 1986. SGML
uses tags to identify the different elements of a document such as title and chapters.
HTML used a similar approach, for example the tag for title is <TITLE>. While HTML
proved powerful in providing a standard method of displaying information that was
easy to learn, it was purely presentational. It lacked the ability to describe the data on
web pages. A metadatalanguage providing data about data contained within pages
would be much more powerful. These weaknesses have been acknowledged, and in an
effort coordinated by the World Wide Web Consortium, the first XML or eXtensible
Markup Languagewas produced in February 1998. This is also based on SGML. The key
word describing XML is ‘extensible’. This means that new markup tags can be created
that facilitate the searching and exchange of information. For example, product infor-
mation on a web page could use the XML tags <NAME>, <DESCRIPTION>, <COLOUR>
and <PRICE>. The tags can effectively act as a standard set of database field descriptions
so that data can be exchanged through B2B exchanges.
The importance of XML for data integration is indicated by its incorporation by
Microsoft into its BizTalk server for B2B integration and the creation of the ebXML (elec-
tronic business XML) standard by their rival Sun Microsystems.Figure 1.15Home page index.html for The B2B Company in a web browser showing
HTML source in text editorMetadata
Literally, data about
data – a format
describing the
structure and content
of data.
XML or eXtensible
Markup Language
A standard for
transferring structured
data, unlike HTML
which is purely
presentational.