.NET & XML

Creating an XmlDocument

Although XmlNode sits at the top of the inheritance tree, XmlDocument is the top-level node in an actual document object tree. The XmlDocument has child nodes, which are accessible through the XmlNode type’s various properties and methods. One of these child nodes, accessible through the DocumentElement property, is an ordinary XmlElement representing the root element of the tree. There may also be a document type node (such as <!DOCTYPE inventory SYSTEM "inventory.dtd">), represented by an XmlDocumentType, accessible through the DocumentType property. Finally, some XML documents will have an XML declaration (such as <?xml version="1.0" encoding="utf-8" standalone="no">), represented by an XmlDeclaration, and accessible only as an ordinary child node of the XmlDocument. Figure 5-3 represents a typical XML document tree structure in memory.

Figure 5-3. Document tree

You can create an XmlDocument in memory either by calling its constructor or by calling XmlImplementation.CreateDocument( ). Both of these methods are overloaded to take an XmlNameTable, and the XmlDocument constructor is also overloaded to take an XmlImplementation.

Tip

XmlNameTable is used to store atomized element and attribute names. It provides a more efficient way to compare the names than using strings. If you create two XmlDocument instances using the same XmlImplementation, they will ...