programs is of less concern. For these reasons as well as
the increasing computer sophistication of managers, the
use of 4 GLs (by whatever name) will continue to grow.
The strongest element of growth will come from end-user
computing, but IS departments will also shift toward
4 GLs, especially for infrequently used applications.
BEYOND THE FOURTH GENERATION LANGUAGES
What comes after the 4 GLs? We already have markup lan-
guages, object-oriented programming languages, and lan-
guages for developing Web applications, and we will turn
to these types of languages next. Another possibility is the
development of natural languages,in which users write
their programs in ordinary English (or something very close
to it). Users will need little or no training to program using
a natural language; they simply write (or perhaps verbalize)
what they want done without regard for syntax or form
(other than that incorporated in ordinary English). At pres-
ent, there are no true natural languages, but some restricted
natural language products have been developed that can be
used with a variety of database management systems and
4 GLs. Commercial developments in the natural language
area have, however, been slower than expected.
Markup Languages
Before turning to object-oriented programming languages,
we should mention the markup languages, which are nei-
ther 3 GLs, 4 GLs, nor OOP languages. Currently the best
known of the markup languages is Hypertext Markup
Language (HTML).HTML is used to create World Wide
Web pages, and it consists of special codes inserted in the
text to indicate headings, bold-faced text, italics, where
images or photographs are to be placed, and links to other
Web pages. HTML version 5, currently under develop-
ment, allows for the embedding of video in HTML files.
Virtual Reality Modeling Language (VRML) provides the
specifications for displaying three-dimensional objects on
the Web; it is the 3-D equivalent of HTML. HTML and the
other markup languages are not really programming lan-
guages in the sense that we have been using this term; they
are simply codes to describe the nature of the associated
data or the way the completed product (the Web page, the
3-D object, and so on) is to appear.
eXtensible Markup Language (XML)is destined
to become even more important than HTML. XML is used
to facilitate data interchange among applications on the
Web; it is really a metalanguage standard for specifying a
document markup language based on plain-text tags. XML
was developed by W3C, the World Wide Web Consortium,
whose goal is to develop open standards for the Web. Other
W3C standards include Hypertext Transfer Protocol
(HTTP)and HTML.
XML is a pared-down version of Standard
Generalized Markup Language (SGML), which was itself
developed by the International Standards Organization
(ISO) in 1986. HTML is another subset of SGML with
which we are more familiar. Both HTML and XML
employ plain-text tags (i.e., made up of ordinary letters,
numbers, and special characters) as a way to “mark up” a
document. However, the similarities between HTML and
XML end there. HTML tags tell a Web browser how to
display various elements on a Web page, while XML tags
identify the nature of the associated data. For example, one
XML tag might identify a customer name as a customer
name, another might identify a customer’s address as an
address, another might identify a number as a product
number, and yet another might identify the quantity sold as
the quantity sold. Entire sets of XML tags are being
defined for particular industries and situations. For exam-
ple,eXtensible Business Reporting Language (XBRL)
is being developed as the standard for publicly traded com-
panies to submit financial documents to the Securities and
Exchange Commission.
The key is that XML is a metalanguage: For each
industry or unique situation, a set of XML tags can be
created to identify the data elements employed in that situ-
ation. XML makes it relatively easy to identify and share
data in order to achieve data integration across organiza-
tional boundaries. XML is “extensible” in that new tags
can be defined as needed, and XML allows the separation
of the presentation of the data from the data themselves.
Through the use of text tags, for example, a company can
identify specific pieces of data on a Web page (such as a
customer order) and can extract the desired data for use
in another application. Thus, XML provides an easy and
effective way to identify and share data.
An XML specification (like HTML) consists of tags
(enclosed in angle brackets: < >). However, XML tags are
intended to convey the meaning of data, not the presenta-
tion format. For example, an HTML tag such as<H1>This data to be displayed in Heading 1 format</H1>
tells the browser to display data using the Heading 1 format.
By contrast, the XML tags given below are an attempt to
represent the meaning of the data related to games.
<Game type=“College Football” date=“9/26/2009”>
Indiana vs. Michigan.
<Score team=“Indiana”>33</Score>
<Score team=“Michigan”>36</Score>
</Game>The top-level tag <Game> specifies that what follows are
details about a game. The attributes for Game (type and48 Part I • Information Technology