Generating a HTTPS header & calculate the body length

Hello,

I am generating an HTTPS header through XSLT 1.0. The content of the XML
should just be copied as body into the HTTPS header.

I would like to know how to calculate the length of the body (which is
the XML part between the <OrderRequest>?  The result would go then in
the Content-length: xxxxx

Any ideas?

Many Thanks,
Houman


<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="html" encoding="ISO-8859-1"/>
<xsl:template match="/RawData">

POST /pls/xml_api.receive_request HTTP/1.1
Content-length: xxxxxx
Content-type: multipart/form-data; boundary=vxvxv
Host: www.bt.com
Authorization:basic ZGFleDE6YXByMjAwMw==
Connection: close

--vxvxv
Content-disposition: form-data; name="p_file_in";
filename="noColonsSpacesOrAmpersandsInHere.typ"
Content-type: text/xml

<xsl:element name="OrderRequest">
	<xsl:copy-of select="*"/>
</xsl:element>
<xsl:
--vxvxv--

</xsl:template>
</xsl:stylesheet>