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

epresents the character that will be used to indent the text of the new node. By default,formatting is on and the indentation is two blanks.Note that all the XML writer's formatting is managed by the writer only before thedocument is actually opened—that is, prior to the WriteStartDocument call. Thefollowing code snippet demonstrates how to write a new XML document, indenting witha tab character any level of the hierarchy:XmlTextWriter writer = new XmlTextWriter(filename, null);writer.Formatting = Formatting.Indented;writer.Indentation = 1;writer.IndentChar = "\t";As a final note, keep in mind that XML formatting normally indents element contentsonly and does not format mixed contents.Supporting NamespacesIn the XmlTextWriter class, all the methods available for writing element nodes andattributes have overloads to work with namespaces. You simply add a new argument tothe call and specify the namespace prefix of choice. A namespace is identified by aURN and is used to qualify both attribute and node names so that they belong to aparticular domain of names.Namespace DeclarationYou insert a namespace declaration in the current node using the xmlns attribute. Youcan also optionally specify a namespace prefix. The prefix is a symbolic name thatuniquely identifies the namespace. To declare a namespace, add a special attribute tothe node that roots the target scope of the namespace, as shown here:You can write this XML text as raw text or use one of the methods of the writer object.Typically, you use one of the overloads of the WriteAttributeString method, as shownhere:public void WriteAttributeString(string prefix,string attr,string ns,string value);You can use this method to declare a namespace, but it remains primarily a method toadd attributes. To obtain a namespace declaration like the one in our earlier examples,a few exceptions to the signature apply. In particular, for an xmlns attribute beingwritten, you instruct the method to add an attribute whose name matches the prefix andwhose prefix equals xmlns.The third argument is expected to be the URN of the namespace for the attribute. Inthis case, however, the namespace prefix named xmlns points to the default XMLnamespace, so the ns argument must be set to null. Note that any attempt to set ns to anon-null value would result in an exception because the specified URN would not matchthe URN of the xmlns namespace prefix. The fourth and final argument, value, containsthe URN of the namespace you are declaring. The following code shows how to declarea sample namespace rooted in the node :writer.WriteStartElement("MyNode");writer.WriteAttributeString("xmlns", "x", null,129