DATABASE SYSTEMS AND THE WEB - Database Design and Development: An Essential Guide for IT Professionals - page 595

Extensible. Extended capabilities to enable you to define your own XML elements.
You can define your own tags to suit your particular needs in the type of document
you are publishing.
Structured. Although flexible and extensible, XML's structured approach helps
conformance to rules—not a free-for-all method.
Descriptive. XML elements concentrate on meaning of the contents, not on their
presentation. The elements can describe what they contain, allowing intelligent
handling of the content by other programs.
Portable. When you define your own tags, how are you going to pass on the defin-
itions and syntax of those tags to others? XML provides simple facilities to produce
files capturing the rules of your elements and tags so that your documents can be
read properly.
Intranets and Extranets
Consider the ease with which you can publish web pages and exchange e-mails over
the Internet. The Internet provides low-cost transmission of information. The
concept of exchanging information using Internet and Web technologies need not
necessarily be confined to a specific set of users. All you need is the set of com-
ponents: a server, a browser, and a set of applet-based applications for exchanging
information. An organization needs the ability to exchange information among
internal users; it also needs information to be made available to a selected set of
outsiders such as distributors, suppliers, and customers.
So why cannot the same paradigm for exchanging information with the public
over the Internet be extended to exchanging information with internal employees
and external business partners? Intranets and extranets are the solution options.
Intranet From the time the term “intranet” was coined in 1995, this concept of a
private network has gripped the corporate world. An intranet is a private computer
network based on the data communications standards of the public Internet. An
intranet may be thought of as a set of websites belonging to an organization and
accessible only to internal users. Information exchange happens within the firewall
and, therefore, is more secure. You can have all the benefits of the popular Web
technology and still manage security better on the intranet. Intranets are less expen-
sive to build and manage.
Extranet The Internet and the intranet have been quickly followed by the extranet.
An extranet is not completely open like the Internet, nor it is restricted to internal
use like an intranet. An extranet is an intranet that is open to selective access by out-
siders. From your extranet, you can look outward to your customers, suppliers, and
other business partners. For the purpose of security, access over the extranet must be
controlled through security mechanisms such as valid user names and passwords. The
Internet itself serves as the communications infrastructure. Web technology provides
the means for publishing information. Tracking packages at the FedEx site and check-
ing balances at your bank's site are examples of extranet applications.