How to apply an XSL Transformation to XML for streaming by using Visual Basic .NET

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Requirements

• Microsoft Visual Studio .NET
• Microsoft Visual Studio .NET Software Development Kit (SDK) QuickStarts

• XML terminology
• Creating and reading an XML file
• XML Path Language (XPath) syntax
• XSL

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How to apply XSL Transformations

1. Create a new Console Application in Visual Basic .NET.
2. Make sure that the project contains a reference to the System.Xml namespace, and add a reference if it does not.
3. Use the Imports statement on the Xml, XPath, and Xsl namespaces so that you are not required to qualify declarations in those namespaces later in your code. You must use the Imports statement prior to any other declarations:

   Imports System.Xml
   Imports System.Xml.XPath
   Imports System.Xml.Xsl
   					

4. Declare the appropriate variables. Declare an XPathDocument object to hold the XML document and an XslTransform object to transform XML documents. Add the declaration code in the Main procedure of Module1:

   Dim myXslTransform As XslTransform
   Dim myXPathDocument As XPathDocument
   					

5. Populate an XPathDocument object with the sample file, Books.xml. The XPathDocument class provides a fast and performance-oriented cache to process XML documents using XSLT. The XPathDocument class is similar to an XML Document Object Model (DOM) but is highly optimized for XSLT processing and the XPath data model.

   'Open the XML.	
   myXPathDocument = New XPathDocument("books.xml")
   					

6. Construct a new XslTransform object. The XslTransform class is an XSLT processor that implements the XSL Transformations (XSLT) version 1.0 recommendation:

   myXslTransform = New XslTransform()
   					

7. Use the Load method to load the XslTransform object with the style sheet. This style sheet transforms the details of the Books.xsl document into a simple International Standard Book Number (ISBN) list of books:

   myXslTransform.Load("books.xsl")
   					

8. Create an XmlTextWriter class with the new, transformed XML file name. Call the Transform method to initiate the transformation.

   Dim writer as XmlTextWriter
   writer = New XmlTextWriter("ISBNBooks.xml",System.Text.Encoding.UTF8)
   myXslTransform.Transform(myXPathDocument,Nothing, writer)
   writer.Flush()
   writer.Close()
   					

9. Alternately, you can send the transformed XML document into an XmlReader, Stream, or TextWriter class. The following code sample sends the XML transformation to an instance of the StringWriter (a derivative of TextWriter), which in turn writes the transformation to the console window.

   Dim stWrite As System.IO.StringWriter = New System.IO.StringWriter()
   myXslTransform.Transform(myXPathDocument, Nothing, stWrite)
   Console.WriteLine(stWrite.ToString)
   Console.ReadLine() 'Pause
   						

   NOTE: The complete code listing uses the preceding code instead of the code in step 8.
10. Build and run your project.The results of the transformation are displayed in the console window as follows:

       <root><bookstore><book ISBN="1-861003-11-0"><price>8.99</price>
    			</book><book ISBN="0-201-63361-2"><price>11.99</price>
    			</book><book ISBN="1-861001-57-6"><price>9.99</price>
    			</book></bookstore></root>
    					

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Complete code listing

Imports System.Xml
Imports System.Xml.XPath
Imports System.Xml.Xsl
Module Module1

    Sub Main()
        Dim myXslTransform As XslTransform
        Dim myXPathDocument As XPathDocument
        myXPathDocument = New XPathDocument("books.xml")
        myXslTransform = New XslTransform()
        myXslTransform.Load("books.xsl")
        Dim stWrite As System.IO.StringWriter = New System.IO.StringWriter()
        myXslTransform.Transform(myXPathDocument, Nothing, stWrite)
        Console.WriteLine(stWrite.ToString)
        Console.ReadLine()
    End Sub

End Module 
				

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