Applied XML Programming for Microsoft .NET.pdf - Csbdu.in

}root.AppendChild(n);n.InnerText = "Content of "+ d.Name;Figure 5-5 demonstrates the structure of the newly created XML file.Figure 5-5: An XML file representing a directory listing created using the XML DOM API.Persisting ChangesThe final step in saving the XML document we have created is to attach the node to the rest of the document and save the document, as shown here:doc.AppendChild(root);doc.Save(fileName);To persist all the changes to a storage medium, you call the Save method, whichcontains four overloads, shown here:public virtual void Save(Stream);public virtual void Save(string);public virtual void Save(TextWriter);public virtual void Save(XmlWriter);The XML document can be saved to a disk file as well as to an output stream, includingnetwork and compressed streams. You can also integrate the class that manages thedocument with other .NET Framework applications by using writers, and you cancombine more XML documents using, in particular, XML writers.Whatever overload you choose, it is always an XML writer that does the job ofpersisting XML nodes to a storage medium. The XmlDocument class makes use of aspecialized version of the XmlTextWriter class that simply works around one of thelimitations of XML writers.XML writers do not allow you to write element and attribute nodes for which you have aprefix but an empty namespace. If the namespace URI is set to null, the writersuccessfully looks up the closest definition for that prefix and figures out thenamespace, if one exists. If the namespace is simply an empty string, however, anArgumentException exception is thrown. The XML DOM internal writer overrides theWriteStartElement and WriteStartAttribute methods. If the namespace URI is emptywhen the prefix is not, the new overrides reset the prefix to the empty string and noexception is raised.193