Unused namespaces begone!

We recently ran into a tricky problem with SOA Suite 11g: unused namespaces in XML files. Consider a simple input file like this one:

<?xml version="1.0" encoding="ISO-8859-1" ?>
<a:A xmlns="http://www.example.org/A" xmlns:a="http://www.example.org/A"
     xmlns:b="http://www.example.org/B">
   <b:B xmlns="http://www.example.org/B">
      <Name>Name 1</Name>
   </b:B>
</a:A>

Now, we want to transform it into an output file that consists of the element B. The transformation is simple:

<?xml version="1.0" encoding="ISO-8859-1" ?>
<xsl:stylesheet version="1.0" xmlns:a="http://www.example.org/A"
                xmlns:b="http://www.example.org/B"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                exclude-result-prefixes="a b">
  <xsl:template match="b:B">
    <xsl:copy-of select="."/>
  </xsl:template>
</xsl:stylesheet>

Unfortunately the result is not so good:

<?xml version = '1.0' encoding = 'UTF-8'?>
<b:B xmlns="http://www.example.org/B" xmlns:b="http://www.example.org/B"
     xmlns:a="http://www.example.org/A">
      <Name>Name1</Name>
</b:B>

The resulting file refers to namespace A. This is allowed by the XSLT specification, but some XML engines fail to read the resulting file as they choke on the unknown namespace. What to do?

Fortunately SOA Suite 11g supports XSLT 2, at least partly. Change version to 2.0 and add copy-namespaces to the copy-of statement:

<?xml version="1.0" encoding="ISO-8859-1" ?>
<xsl:stylesheet version="2.0"
                xmlns:a="http://www.example.org/A"
                xmlns:b="http://www.example.org/B"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                exclude-result-prefixes="a b">
  <xsl:template match="b:B">
    <xsl:copy-of select="." copy-namespaces="no"/>
  </xsl:template>
</xsl:stylesheet>

This produces the desired result. XSLT 2 has many other useful features, so it is well worth investigating even though it is not fully supported in SOA Suite yet.