Visual Basic 2005: A Developer's Notebook

Use the New XPathDocument and XPathNavigator

.NET provides a range of options for dealing with XML in the System.Xml namespaces. One common choice is XmlDocument, which lets you navigate in-memory XML as a collection of node objects. For more efficient performance, the XmlWriter and XmlReader classes offer a streamlined way to read and write a stream of XML. Unfortunately, neither solution is perfect. The XmlDocument consumes too much memory, and navigating its structure requires too much code. Furthermore, because the XmlDocument is based on a third-party standard (the XML DOM, or document object model), it's difficult to improve it without breaking compatibility. On the other hand, the XmlWriter and XmlReader are too restrictive, forcing you to access information linearly from start to finish. They also make it prohibitively difficult for a developer to provide an XML interface to non-XML data.

Note

Talk about an improvement! The revamped XPathDocument sets a new standard for XML parsing in . NET.

.NET 2.0 proposes a solution with the System.Xml.XPath.XPathDocument. The XPathDocument is a cursor-based XML reader that aims to become the only XML interface you need to use. It gives you the freedom to move to any position in a document, and it provides blistering speed when used with other XML standards such as XQuery, XPath, XSLT, and XML Schema validation.

How do I do that?

To use an XPathDocument, you begin by loading the document from a stream, XmlReader, or URI (which can ...