You use XLinks to create links in XML, like HTML hyperlinks but considerably more extended. Any XML element can be an XLinkall you have to do is to use the correct attributes. The one required attribute, xlink:type , sets the type of XLink, and the possible values are simple , extended , locator , arc , resource , title , or none .
XPointers let you narrow down your searches even more, down to specific nodes or even specific characters in text. The XPointer specification is divided into three Recommendationsthe XPointer framework, the element scheme, and the namespace schemealong with the Working Draft for the general XPointer scheme. This division was made to make XPointers easier to implement.
The XPointer framework shows how you can use element namesreferred to as barenamesas XPointers, the element scheme shows how you can identify elements by ID, and the namespace scheme shows how to use namespaces in XPointers.
The general XPointer scheme is where the full power of XPointers appears because you can use full XPath 1.0 expressions here. General XPointers are so powerful because they support full XPath expressions, as well as two more data typespoints and ranges.
On the other hand, the other technique we looked at in this chapterXQueryis really where the future action is going to be when it comes to data access. Although still just in W3C Working Draft stage, XQuery is generating a lot of excitement, and we got a good introduction to it here. Using the Galax XQuery processor, we were able to create XQuery variables and functions, and used them to successfully query the data in an XML document and extract what we wanted.
