XML Transform Changes

3.1.1.1   .NET 1.1

In .NET 1.1, the XSL runtime often blurred the line between XML node fragements and XML node sets. So the following code worked in .NET 1.1 XSL transforms:

<xsl:variable name="VarResult">
 <html:html>
  <html:head>
   <html:title>Wow!</html:title>
  </html:head>
  <html:body>
   <html:h2>Wow!</html:h2>
  </html:body>
 </html:html>
</xsl:variable>
<xsl:variable name="VarWriteDocument" select="wwexsldoc:Document($VarResult, 'C:\test.html', 'utf-8')" />

3.1.1.2   .NET 2.0

The XSL 1.1 specification states that node fragments are distinct from node sets and XSL processors should not allow them to be used interchangably. The .NET 2.0 XSL runtime strictly enforces this policy. Therefore, XSL developers must explicitly convert node fragments to node sets via the Microsoft msxsl:node-set() method.

3.1.2.1   .NET 1.1

In .NET 1.1, XML elements were always written literally. So, XSL code to emit a non-empty element:

<xsl:element name="script" namespace="http://www.w3.org/HTML/1999">
 <xsl:attribute name="src">
  <xsl:value-of select="'scripts/webworks.js'" />
 </xsl:attribute>
</xsl:element>

results in:

<script src="scripts/webworks.js"></script>

This meant that <img> elements could be problematic because they must be empty elements:

<xsl:element name="img" namespace="http://www.w3.org/HTML/1999">
 <xsl:attribute name="src">
  <xsl:value-of select="'images/pretty.jpg'" />
 </xsl:attribute>
</xsl:element>

results in:

<img src="images/pretty.jpg"></img>

This is not appropriate for HTML or XHTML output. Therefore, two work-arounds were used in ePublisher 9.0 and 9.1:

Value Attribute Templates::

  <xsl:variable name="$VarSrc" select="'images/pretty.jpg'" />
  <img src="{$VarSrc}" />

wwexsldoc:MakeEmptyElement() extension method::

  <xsl:variable name="VarImgAsXML">
   <xsl:element name="img" namespace="http://www.w3.org/HTML/1999">
    <xsl:attribute name="src">
     <xsl:value-of select="'images/pretty.jpg'" />
    </xsl:attribute>
   </xsl:element>
  </xsl:variable>
  <xsl:variable name="VarImg" select="msxsl:node-set($VarImgAsXML)/*" />
  <xsl:copy-of select="wwexsldoc:MakeEmptyElement($VarImg)" />

Either method produces the required empty element:

<img src="images/pretty.jpg" />

3.1.2.2   .NET 2.0

In .NET 2.0, XML elements are automatically optimized by the XSL/XML runtime. So there is no need to use work-arounds such as Value Attribute Templates and wwexsldoc:MakeEmptyElement():

<xsl:element name="img" namespace="http://www.w3.org/HTML/1999">
 <xsl:attribute name="src">
  <xsl:value-of select="'images/pretty.jpg'" />
 </xsl:attribute>
</xsl:element>

results in:

<img src="images/pretty.jpg" />

Unfortunately, this is a problem for elements such as <script>, which is required to be a non-empty element in HTML and XHTML:

<xsl:element name="script" namespace="http://www.w3.org/HTML/1999">
 <xsl:attribute name="src">
  <xsl:value-of select="'scripts/webworks.js'" />
 </xsl:attribute>
</xsl:element>

results in:

<script src="scripts/webworks.js" />

There is no way to force a non-empty element without introducing white space or text. While this might work for <script> elements, it is not a suitable work-around for <a> elements.

3.1.3.1   .NET 1.1

XSL allows pretty printing of XML output as long as raw text is not emitted within a given context. So, consider the following XSL code:

<html:div>
 <html:span style="color: red;">
  <xsl:value-of select="'F'" />
 </html:span>
 <html:span style="color: blue;">
  <xsl:value-of select="'irst'" />
 </html:span>
 <html:span style="color: black;">
  <xsl:value-of select="' letter and word are different.'" />
 </html:span>
</html:div>

When emitted to XML, HTML, or XHTML, the result is:

<div>
 <span>F</span>
 <span>irst</span>
 <span>letter and word are different.</span>
</div>

While this is perfectly valid XML, where white space significance has different rules, this will not render properly in web browsers:

F irst letter and word are different.

To side-step this issue, for .NET 1.1 we emitted an empty text block to prevent the XSL/XML runtime from pretty printing in such a situation:

<html:div>
 <html:span style="color: red;">
  <xsl:value-of select="'F'" />
 </html:span>
 <xsl:text></xsl:text>
 <html:span style="color: blue;">
  <xsl:value-of select="'irst'" />
 </html:span>
 <xsl:text></xsl:text>
 <html:span style="color: black;">
  <xsl:value-of select="' letter and word are different.'" />
 </html:span>
</html:div>

which results in the expected:

First letter and word are different.

3.1.3.2   .NET 2.0

In .NET 2.0, the same code that optimizes empty elements also strips out empty text blocks. So the above work-around no longer works since:

<html:div>
 <html:span style="color: red;">
  <xsl:value-of select="'F'" />
 </html:span>
 <xsl:text></xsl:text>
 <html:span style="color: blue;">
  <xsl:value-of select="'irst'" />
 </html:span>
 <xsl:text></xsl:text>
 <html:span style="color: black;">
  <xsl:value-of select="' letter and word are different.'" />
 </html:span>
</html:div>

results in:

F irst letter and word are different.

There is no way to modify this behavior without introducing invalid markup into the output short of disabling all XML/XSL pretty print features.