Functions in xsl:sort

Question

Is it possible to use extension functions in the select attribute of xsl:sort? This way I could sort the nodes based on a computed value.
e.g. <xsl:sort select="myns:myextfunc(ELEM1, ELEM2)">
I tried using a standard XSL function like
<xsl:sort select="concat(ELEM1, ELEM2)"/> and it seems to work but when I try to use an extension function it fails.
TIA
null

Answer 1

With XML Parser 9.0.1 Production, this works for me:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:ext="http://www.oracle.com/XSL/Transform/java/Ext">
<xsl:output method="text"/>
<xsl:template match="/">
<xsl:for-each select="/Employees/Emp">
<!--
| Due to a bug, need to declare the extension namespace on
| the <xsl:sort> element itself.
+-->
<xsl:sort data-type="number" order="descending" select="ext:max(Salary,Bonus)"
xmlns:ext="http://www.oracle.com/XSL/Transform/java/Ext"/>
<xsl:value-of select="Name"/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
public class Ext
public static double max( double n, double m ) {
return n > m ? n : m;
<Employees>
<Emp>
<Name>B</Name>
<Salary>10</Salary>
<Bonus>12</Bonus>
</Emp>
<Emp>
<Name>C</Name>
<Salary>25</Salary>
<Bonus>12</Bonus>
</Emp>
<Emp>
<Name>A</Name>
<Salary>10</Salary>
<Bonus>2</Bonus>
</Emp>
</Employees>If I make sure Ext.class is in my CLASSPATH, and transform the above XML by the above stylesheet, I get:
CBA
which is the reverse-numerically-sorted list of max() calculations.