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

The XslTransform ClassNow that we've seen how the XslTransform class implements the .NET Frameworkprocessor to transform XML data into arbitrary text using XSL style sheets, let's lookmore closely at its programming interface.As shown in the following code, XslTransform has only the default constructor. Inaddition, it is a sealed class, meaning that you can use it only as is and other classescan't inherit from it.public sealed class XslTransform{}⋮The programming interface of the class is fairly simple and consists of just one publicproperty and a couple of methods.Properties of the XslTransform ClassThe only property that the XslTransform class exposes is XmlResolver, which handlesan instance of the XmlResolver class. Interestingly, the XmlResolver property is writeonly—thatis, you can set it, but you can't check the currently set resolver object.As we've seen in previous chapters, the XmlResolver object is used to resolve externalreferences found in the documents being processed. In this context, the XmlResolverproperty is used only during the transformation process. It is not used, for example, toresolve external resources during load operations.If you don't create a custom resolver object, an instance of the XmlUrlResolver class isused.Methods of the XslTransform ClassTheXslTransform class supplies two methods specific to its activity—the Load andTransform methods mentioned earlier. The Load and Transform methods are describedin more detail in Table 7-5.Table 7-5: Methods of the XSLT ProcessorMethodDescriptionLoadLoads the specified XSLT style sheet document from a numberof possible sources, including remote URLs and XML readers.The method has several overloads, including overloads that letyou specify a custom XmlResolver object to load any stylesheets referenced through xsl:import and xsl:includestatements.Transform Transforms the specified XML data using the loaded XSLTstyle sheet and writes the results to a given stream. Some ofthe method's overloads let you specify an argument list asinput to the transformation.The following code snippet shows how to use an XmlResolver object with credentials toaccess a remote XSLT style sheet:XmlUrlResolver resolver = new XmlUrlResolver();NetworkCredential cred = new NetworkCredential(uid, pswd,domain);resolver.Credentials = cred;XslTransform xslt = new XslTransform();252