Getting prefix of a namespace - xslt

Question

I'm developing an application and I need to add several elements into the header of soap message I receive. The problem is I don't know which prefix the namespace I'm using for adding these elements is using, but it's sure there will be several elements in the body using this prefix, so the namespace is already declared in the message.
For example, I'm receiving this message:
<soapenv:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:enterprise.soap.sforce.com" xmlns:urn1="urn:sobject.enterprise.soap.sforce.com">
<soapenv:Header/>
<soapenv:Body>
<urn:operation>
</urn:operation>
</soapenv:Body>
</soapenv:Envelope>
And the xpath expression I use for adding these elements in the header is:
<xsl:stylesheet version="1.0" exclude-result-prefixes="xsi xsl" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<xsl:output method="xml" encoding="UTF-8" indent="yes" omit-xml-declaration="yes"/>
<xsl:param name="Getsed">aBcDeFgHiJkLmNñOpQrStUvWxYz</xsl:param>
<xsl:template match="#* | node()">
<xsl:copy>
<xsl:apply-templates select="#* | node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="//*[local-name()='Header']">
<xsl:copy>
<urn:SH xmlns:urn="urn:enterprise.soap.sforce.com">
<urn:sed><xsl:value-of select="$Getsed"/></urn:sed>
</urn:SH>
<xsl:apply-templates select="node()|#*"/>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
I would like to use the prefix (urn) already declared for the namespace urn:enterprise.soap.sforce.com.
Could you please give me a hand?

Answer 1

I believe a silly workaround like <xsl:value-of select="substring-before(name(//*[namespace-uri() = 'urn:enterprise.soap.sforce.com']), ':')" /> will fit your needs.
Thus your template can be rewrited that way:
<xsl:template match="*[local-name()='Header']">
<!-- this will retrieve the namespace prefix in source document -->
<xsl:variable name="ns-sforce">
<xsl:value-of select="substring-before(name(//*[namespace-uri() = 'urn:enterprise.soap.sforce.com']), ':')" />
</xsl:variable>
<xsl:copy>
<!-- create prefixed elements with the same value as before -->
<xsl:element name="{$ns-sforce}:SH" namespace="urn:enterprise.soap.sforce.com">
<xsl:element name="{$ns-sforce}:sed" namespace="urn:enterprise.soap.sforce.com">
<xsl:value-of select="$Getsed"/>
</xsl:element>
</xsl:element>
<xsl:apply-templates select="node()|#*"/>
</xsl:copy>
</xsl:template>
Note: <xsl:template match="//*[local-name()='Header']"> can be replaced by <xsl:template match="*[local-name()='Header']">