I mentioned in my last blog post that you can use scripts in XSLT, so I just wanted to show shortly how you can use scripts to show the power it can yield.
Firstly – add a namespace to your XSLT file:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:msxsl="urn:schemas-microsoft-com:xslt"
                xmlns:scripts="urn:scripts.this">

Then you can use the scripts in various situations.
For example, I had to parse some "Yes" and "No" into Boolean strings "true" and "false" (for business logic reasons) so I made a script for that in the bottom of my XSLT file (I made the scripts in C# syntax):

<msxsl:script language="C#" implements-prefix="scripts">
    <![CDATA[
        //return true or false as string instead of "yes" and "no"
    public string getBooleanString(string s0)
    {
      if ((String.Equals(s0, "yes", StringComparison.OrdinalIgnoreCase))
      { return "true"; }
      if (String.Equals(s0, "no", StringComparison.OrdinalIgnoreCase))
      { return "false"; }
      return s0;
    }
    ]]>
</msxsl:script>

Now, I could use this script in my XSLT matching like this:

<xsl:value-of select ="scripts:getBooleanString(./VALUE)"/>

This makes a call to the C# script “getBooleanString” with the value, the script will test it for “Yes” and “No” and return “true” or “false” respectively, or the string itself it it wasn’t one of the two.
Some of the other things I used this for was to compare strings case with case insensitive, and to hold temporary values to avoid having to run through my XSLT file multiple time in the transformation process.  I also had to convert some number formats to use period as decimal point instead (due to language specific settings), so I made a script which changes between period and comma.

It is a powerful tool to have in the XSLT toolbox.

I have been working quite a bit with doing XSLT on some large XML files lately.
During this I worked with the XslCompiledTransform class in .NET, which make transformations really easy and it works very fast.

An advantage of this class is also that it enables you to utilize scripts within your XSLT file, which enables you to make for example C# functions, for various tasks. I’ll write more about that in a later blog entry to keep this one simple and to the point.

The syntax (in vb.net) for doing a transformation using XslCompiledTransform is as simple as the following:

    'Create settings which eanble scripting in the XSLT file
    Dim xmlSettings As New XsltSettings
    xmlSettings.EnableScript = True
    'create a XML reader for the XLST file
    Dim xsltFile As XmlReader = XmlReader.Create("XSLT FILE")
    'create a Transform object
    Dim xslTransform As New XslCompiledTransform
    'Load XSLT file with Settings into transform object
    xslTransform.Load(xsltFile, xmlSettings, Nothing)
    'Do the transformation.
    xslTransform.Transform("INPUT XML FILE", "OUTPUT XML FILE")  

The main disadvantage I’ve found for using this transformation is the huge memory usage it uses.
In my own situation, the process used about 3.5 times as much memory as my source XML file, meaning that a source file about 450MB my .NET process was killed on a 32 bit computer with an out of memory exception.

The actual memory usage will of course vary depending on how complex your transformation is, so the 3.5 number is not meant to be nothing more than an indicator that it is memory intensive.
It is however very fast, and I managed to transform very large files in a manner of seconds, thus if you can live with the memory consumption it is quite effective.