Beginning XML - Part IV(Basic Schema Of A DTD)

In the following two articles, I'm going to wrap up my pondering
on XML. We'll explore the basic schema of a DTD, and the future
of XML.

Let's recall that some basic features of XML are:

· XML can keep data separated from your HTML
· XML can be used to store data inside your HTML documents
· XML can be used as a format to exchange information
· XML can be used to store data in files or in databases

The power and beauty of XML is that it maintains the separation
of the user interface from structured data, allowing the seamless
integration of data from diverse sources. Customer information,
purchase orders, research results, bill payments, medical
records, catalog data and other information can be converted to
XML on the middle tier, allowing data to be exchanged online as
easily as HTML pages display data today. Data encoded in XML can
then be delivered over the Web to the desktop. No retrofitting is
necessary for legacy information stored in mainframe databases or
documents, and because HTTP is used to deliver XML over the wire,
no changes are required for this function.

Once the data is on the client desktop, it can be manipulated,
edited, and presented in multiple views, without return trips to
the server. Servers now become more scalable, due to lower
computational and bandwidth loads. Also, since data is exchanged
in the XML format, it can be easily merged from different
sources - ok, this is the aspects that personally interests me.
The portability of data. Database programmer all over the world
face unlimited problems while tackling with data of multifarious
formats. If formats cease to matter, anybody, anywhere, on
whichever machine, can view and manipulate the data.

>From the previous article, we might recall the XML, unlike HTML,
does not have proprietary tags. We can go on a wild trip and
define our own tags, according to the necessity. Consider this
for example:



4/17/2001


Telling what exactly XML
means
Some Examples of XML
Some concluding text
Email the XML files to Yagna




Have something light to eat and laze around



Work on a client's web site


............
4/18/2001
..............


If you can't make out what this is all about, don't worry. This
is just an imaginary schema of a data structure that can be
represented through an XML document.

Before you get the time to come to grips with the gory XML
introduction, I present a more evolved version of the above
mentioned XML code:



mid-noon-to-evening)>

XML-Conclusion, XML-Email)>






]>

4/17/2001


Telling what exactly XML
means
Some Examples of XML
Some concluding text
Email the XML Article




Have something light to eat and laze around



Work on a client's web site


............
4/18/2001
..............


The above is a comprehensive example of a DTD - Document Type
Definition. XML provides an application independent way of
sharing data. With a DTD, independent groups of people can use a
common DTD for interchanging data. Your application can use a
standard DTD to verify that the data you receive from the outside
world is valid. You can also use a DTD to verify your own data.

In this example, the data structure is well defines. Each parent
node has a child node, and some child-nodes have grand-child
nodes and so on.