It's a fact of life that XML, which stands for eXtensible Markup Language, is invading our lives more and more as programmers, and I feel this is a good thing. The reason being XML has the ability to cross all sorts of boundaries, and probably the only chance we have to obtain a truly independent, cross-platform data transfer format.
Parts of an XML document: The various building blocks of an XML document is shown in the document below. And this will be a recap to what we have already learnt.
The Prolog consisits of two internal blocks : • The first block defines the XML version declaration which is optional. <?xml version = "1.0" ?> • DTD (document type definition) OR SCHEMA
PROLOG
VERSION
DECLARATION
DTD OR SCHEMA
<ROOT>
BODY…..
</ROOT>
XML Style Sheets
XML documents, unlike HTML, contain absolutely no formatting directives. Instead, an XSL (XML style sheet) is applied to the XML document. Think of a style sheet as a pre-processor for the actual graphical flow-engine that creates the final layout. The style sheet contains functions and rules for every element type. The functions are written in Scheme (a programming language derived from LISP) and have access to the full structure of the XML document being processed. This means that elements can be processed conditionally, for example, based upon their parent-element type (or some other relevant factor).
It is beyond the scope of this document to discuss XSL style sheets. However, the concept of applying a style sheet as part of the server-side processing is in fact extremely interesting and relevant to the discussion vis-a-vis server-side XML processing. I like to think of style sheets as transformation engines, which are capable of transforming an XML document into something else--for instance, a database record--or an HTML document.
