SAX2

What XML Are We Talking About?

Over the past years, there has been an explosive growth in the number of XML-related standards. Talking about XML has become confusing, because those three letters can mean so many different things. Some people actually mean what I’ve called “Greater XML.” Think of it this way: Boston is significant city, but people who don’t live there may often name Boston to refer to other nearby towns (Arlington, Cambridge, and so on). What they’re really talking about is the “Greater Boston Metropolitan Area,” or sometimes even just “Eastern Massachusetts.”

In much the same way, many people now talk about “XML” when they really mean one of dozens of related technologies built around the nucleus of XML. Some of these may even be part of the original XML vision as “SGML for the Web.” Using XML to develop documents using a DTD like DocBook (http://www.docbook.org) is clearly part of that original open systems vision. However, it’s also been trendy to market “new and improved!” software as based on XML. Such ambiguities can be confusing and can even implicitly promote vendor lock-in, rather than liberate customer data from vendor control. The simplicity at the core of XML isn’t friendly to lock-in strategies, but complex application layers on top of XML can certainly cause closed systems.

So when someone says that SAX is a great API for XML processing, exactly what part of Greater XML does that mean? Briefly, parts built with the “core” XML specifications. The ...