Datasheet

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Chapter 1 ✦ An Eagle’s Eye View of XML
HTML is also somewhat independent of the programs that read and write it, but it’s
really only suitable for browsing. Other uses, such as database input, are beyond
its scope. For example, HTML does not provide a way to force an author to include
certain required content such as the ISBN in every book. XML enables you to do
this. You can even control the order in which particular elements appear (for
example, that level 2 headers must always follow level 1 headers).
Related Technologies
XML doesn’t operate in a vacuum. Using XML as more than a data format involves
several related technologies and standards, including the following:
✦ HTML for backward compatibility with legacy browsers
✦ The CSS and XSL style sheet languages to define the appearance of XML
documents
✦ URLs and URIs to specify the locations of XML documents
✦ XLinks to connect XML documents to each other
✦ The Unicode character set to encode the text of an XML document
HTML
Mozilla 1.0, Opera 4.0, Internet Explorer 5.0, and Netscape 6.0 and later provide some
(albeit incomplete) support for XML. However, it takes about two years before most
users have upgraded to a particular release of the software (in 2004, my wife still
uses Netscape 4 on her Mac at work), so you’re going to need to convert your XML
content into classic HTML for some time to come.
Therefore, before you jump into XML, you should be completely comfortable with
HTML. You don’t need to be a hotshot graphical designer, but you should know how
to link from one page to the next, how to include an image in a document, how to
make text bold, and so forth. Because HTML is the most common output format of
XML, the more familiar you are with HTML, the easier it will be to create the effects
you want.
On the other hand, if you’re accustomed to using tables or single-pixel GIFs to
arrange objects on a page, or if you begin planning a web site by sketching out its
design in Photoshop, you’re going to have to unlearn some bad habits. As previously
discussed, XML separates the content of a document from the appearance of the
document. You develop the content first, and then design a style sheet that formats
the content. Separating content from presentation is an extremely effective technique
that improves both the content and the appearance of the document. Among other
things, it enables authors, programmers, and designers to work more independently
of each other. However, it does require a different way of thinking about the design
of a web site, and perhaps even the use of different project management techniques
when multiple people are involved.
Note
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