HTML and CSS Reference
power of XML lies not in the document-display arena, but in the world of
data capture and exchange.
Despite the billions of computers deployed worldwide, sharing data is as
tedious and error-prone as ever. Competing applications do not oper-
ate from common document-storage formats, so sending a single docu-
ment to a number of recipients is fraught with peril. Even when vendors
attempt to create an interchange format, it still tends to be propriet-
ary and often is viewed as a competitive advantage for participating
vendors. There is little incentive for vendors to release application code
for the purpose of creating easy document-exchange tools.
XML avoids these problems. It is platform neutral, is generic, and can
perform almost any data-capture task. It is equally available to all
vendors and can easily be integrated into most applications. The stabil-
ization of the XML standard and the increasing availability of XML au-
thoring and parsing tools is making it easier to create XML markup lan-
guages for document capture and exchange.
Most importantly, document exchange rarely requires document
presentation, thus eliminating "display difficulties" from the equation.
Often, an existing application uses XML to include data from another
source and then uses its own internal display capabilities to present the
data to the end user. The cost of adding XML-based data exchange to
existing applications is relatively small.
15.8.3. Connecting Systems
A level below applications, there is also a need for systems to exchange
data. As business-to-business communication increases, this need
grows even faster. In the past, this meant that someone had to design
a protocol to encode and exchange the data. With XML, exchanging data
is as easy as defining a DTD and integrating the parser into your exist-
The data sets exchanged can be quite small. Imagine shopping for a
new PC on the Web. If you could capture your system requirements as a
small document using an XML DTD, you could send that specification to