18.1.5- Breaking Beyond Data Display

Breaking Beyond Data Display

Up to now, it may seem as though we have been concentrating on how XML can be an alternative to HTML. Let's quickly expand this view a little and see the other effects of marking up our data as XML. We will then take a look at some of the associated specifications and techniques that you need to learn.

As XML is just stored and transferred as plain text it has strong advantages over most other data formats. For example, because it is pure text it is not a proprietary format that can only be used on certain platforms or with limited applications – any application could be written to accept pure text. Also, the data is easy to validate. You may recall that we said SGML uses a DTD to define the rules of any markup language written in SGML. Well, so does XML. This means that applications can verify the structure and content of an XML file.

This universality is one of the main reasons why XML is an ideal subject for applications, as well as displaying data on the web. It can transcend different operating systems and is ideal for distributed computing environments.

So, not only are we seeing XML being used as a way of presenting data that is marked up as HTML, it is also being used for many other purposes, including:

• Data transfer, from the book details we could send details of orders and financial transactions, in XML, that will be able to be understood by any platform
• Re-usable data storage in plain text files rather than pre-purposed formats, such as HTML and proprietary word processor files
• Interface descriptors for components, as you have seen with Windows Script Components

Of course, we cannot cover all of the reasons in this chapter. But what we will do is teach you enough to get you using XML. From this point you will be able to see how it can help you in your programming activities.

Perhaps you've already decided that XML is something you definitely need to find out more about. In which case you might want to refer to two other books published by Wrox : Professional XML ISBN 0-471-77777-3 is an excellent new resource as is Beginning XML 4th Edition ISBN 0-470-11487-8. Both of these books are current and are available from Wrox or your favorite retailer.