XML and Related Specs: Digesting the Alphabet Soup

ThIS appendix provides a high-level overview of the various XML-related acronyms and what they mean. There is a lot of work going on around XML, so there is a lot to learn.

The current APIs for accessing XML documents either serially or in random access mode are, respectively, SAX and DOM. The specifications for ensuring the validity of XML documents are DTD (the original mechanism, defined as part of the XML specification) and various Schema Standards proposals (newer mechanisms that use XML syntax to do the job of describing validation criteria).

Other future standards that are nearing completion include the XSL standard, a mechanism for setting up translations of XML documents (for example to HTML or other XML) and for dictating how the document is rendered. The transformation part of that standard, XSLT (+XPath), is completed and covered in this tutorial. Another effort nearing completion is the XML Link Language specification (XML Linking), which enables links between XML documents.

Those are the major initiatives you will want to be familiar with. This appendix also surveys a number of other interesting proposals, including the HTML-lookalike standard, XHTML, and the meta-standard for describing the information an XML document contains, RDF. There are also standards efforts that extend XML's capabilities, such as XLink and XPointer.

Finally, there are a number of interesting standards and standards proposals that build on XML, including Synchronized Multimedia Integration Language (SMIL), Mathematical Markup Language (MathML), Scalable Vector Graphics (SVG), and DrawML, as well as a number of e-commerce standards.

The remainder of this appendix gives you a more detailed description of these initiatives. To help keep things straight, it's divided into these topics:

Skim the terms once so you know what's here, and keep a copy of this document handy to refer to whenever you see one of these terms in something you're reading. Pretty soon, you'll have them all committed to memory, and you'll be at least "conversant" with XML.