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PRB: XSL Transformations with XmlDataDocument May Perform More Slowly Than XPathDocument

Article ID: 318580 - View products that this article applies to.

This article was previously published under Q318580

SYMPTOMS

XSL transformations (XSLT) with System.Xml.XmlDataDocument may run more slowly than XSLT with XPathDocument or XmlDocument.

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CAUSE

XmlDataDocument is primarily designed to act as the bridge between the DataSet and XML.

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Run XSL transformations by using the XmlDocument or XPathDocument classes instead of XmlDataDocument. Microsoft recommends that you use XPathDocument, because it is highly optimized for XSL transformations. See the "More Information" section of this article for a code sample that uses the XPathDocument.

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STATUS

This behavior is by design. The XmlDataDocument class is primarily designed for synchronizing XML with DataSet. Microsoft is looking into improving its performance for transformations in the next major release of Visual Studio .NET.

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MORE INFORMATION

The following is a Visual Basic .NET code sample that shows you how to apply XSL transformations on a DataSet by using the XPathDocument class. The sample initially loads the data from the Customers table and the Order table of the Northwind database into to a DataSet, and then the DataSet is transformed with the XmlDataDocument and XPathDocument classes.

Steps to Reproduce the Behavior

Create a new Visual Basic .NET Console application project.

Copy and paste the following into a file, and then save the file as Transform.xsl in the bin directory of the application:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">

<xsl:template match="CustomerOrders">
  <HTML>
  <STYLE>
  BODY {font-family:verdana;font-size:9pt}
  TD   {font-size:8pt}
  </STYLE>
    <BODY>
    <TABLE BORDER="1">
      <xsl:apply-templates select="Customers"/>
    </TABLE>
    </BODY>
  </HTML>
</xsl:template>

<xsl:template match="Customers">
    <TR><TD>
      <xsl:value-of select="ContactName"/>, <xsl:value-of select="Phone"/><BR/>
    </TD></TR>
      <xsl:apply-templates select="Orders"/>
</xsl:template>

<xsl:template match="Orders">
  <TABLE BORDER="1">
    <TR><TD valign="top"><B>Order:</B></TD><TD valign="top"><xsl:value-of select="OrderID"/></TD></TR>
    <TR><TD valign="top"><B>Date:</B></TD><TD valign="top"><xsl:value-of select="OrderDate"/></TD></TR>
    <TR><TD valign="top"><B>Ship To:</B></TD>
        <TD valign="top"><xsl:value-of select="ShipName"/><BR/>
        <xsl:value-of select="ShipAddress"/><BR/>
        <xsl:value-of select="ShipCity"/>, <xsl:value-of select="ShipRegion"/>  <xsl:value-of select="ShipPostalCode"/><BR/>
        <xsl:value-of select="ShipCountry"/></TD></TR>
  </TABLE>
</xsl:template>

</xsl:stylesheet>

Replace the code in Module1.vb file with the following.

Imports System.IO
Imports System.Data
Imports System.Data.SqlClient
Imports System.Xml
Imports System.Xml.Xsl
Imports System.Xml.XPath

Module Module1

   Sub Main()

      Try
         ' Fill a DataSet with data from Customers and Orders tables of northwind database
         Dim nwindConn As SqlConnection = New SqlConnection("Password=;User ID=sa;Initial Catalog=Northwind;Data Source=localhost")
         nwindConn.Open()

         Dim myDataSet As DataSet = New DataSet("CustomerOrders")
         Dim custDA As SqlDataAdapter = New SqlDataAdapter("SELECT * FROM Customers", nwindConn)

         custDA.Fill(myDataSet, "Customers")

         Dim ordersDA As SqlDataAdapter = New SqlDataAdapter("SELECT * FROM Orders", nwindConn)
         ordersDA.Fill(myDataSet, "Orders")
         nwindConn.Close()

         myDataSet.Relations.Add("CustOrders", _
                                 myDataSet.Tables("Customers").Columns("CustomerID"), _
                                 myDataSet.Tables("Orders").Columns("CustomerID")).Nested = True
         ' Load the stylesheet 
         Dim xslTran As XslTransform = New XslTransform()
         xslTran.Load("transform.xsl")
         ' Create a writer to stream the results to a file
         Dim writer As XmlTextWriter = New XmlTextWriter("xslt_output.html", System.Text.Encoding.UTF8)

         ' I. Transform the DataSet data with XmlDataDocument
         Dim startTime As DateTime
         ' Synchronize an XmlDataDocument with the DataSet
         Dim xmlDataDoc As XmlDataDocument = New XmlDataDocument(myDataSet)
         startTime = DateTime.Now
         xslTran.Transform(xmlDataDoc, Nothing, writer)
         Console.WriteLine("Time taken with XmlDataDocument: " + ((DateTime.Now).Subtract(startTime)).TotalSeconds.ToString())

         ' II. WORKAROUND: Use XPathDocument to transform the DataSet data
         Dim xpathDoc As XPathDocument = New XPathDocument(New StringReader(myDataSet.GetXml()))
         startTime = DateTime.Now
         xslTran.Transform(xpathDoc, Nothing, writer)
         Console.WriteLine("Time taken with XPathDocument  : " + ((DateTime.Now).Subtract(startTime)).TotalSeconds.ToString() + vbNewLine)
         Console.ReadLine()
         writer.Close()

      Catch e As Exception
         Console.WriteLine("{0}", e.Message)
      End Try

   End Sub
End Module

Modify the connection string to suit your database settings. Compile and run the application. Read the inline comments to understand the functionality of the code.

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