Obtaining the complete XML message as xs:string with XSLT

At a recent project I needed to implement functionality which would store an incoming message in a relational database. Since we were using the WSO2 platform I created a WSO2 DataService for this by generating a Data WebService based in my MySQL table. Each message supplied to this service in the following XML format would be inserted in a MySQL database.

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="originalMessage" type="originalMessageType"/>
  <xs:complexType name="originalMessageType">
    <xs:sequence>
      <xs:element type="xs:string" name="id"/>
      <xs:element type="xs:string" name="content"/>
    </xs:sequence>
  </xs:complexType>
</xs:schema>

Of course it was a little more complex XML but the idea remains. The content of these two elements were stored in a table ‘ARCHIVE’ which had 2 columns ‘ID’ and ‘MESSAGE’. The tricky part was how to get the original XML message in the ‘content’ element of the ‘Data Service’ format. The original message format was:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="message" type="messageType"/>
  <xs:complexType name="messageType">
    <xs:sequence>
      <xs:element type="xs:string" name="messageID"/>
      <xs:element type="xs:string" name="order"/>
      <xs:element type="xs:string" name="price"/>
    </xs:sequence>
  </xs:complexType>
</xs:schema>

Well, it turned out to be quite easy (although not possible with my favorite mapping tool Altova Mapforce). I just had to ‘escape’ the XML that is put in the ‘content’ element as CDATA part. The XSLT that does this looks like:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:template match="/">
        <originalMessage>
            <id>
                <xsl:value-of select="/message/messageID" />
            </id>
            <content>
                <xsl:text disable-output-escaping="yes">&lt;![CDATA[</xsl:text>
                <xsl:copy-of select="/"/>
                <xsl:text disable-output-escaping="yes">]]&gt;</xsl:text>
            </content>
        </originalMessage>
    </xsl:template>
</xsl:stylesheet>

This will transform an input XML message like this:

<message>
    <messageID>123</messageID>
    <order>abc</order>
    <price>123,45</price>
</message>

To the result XML:

<?xml version="1.0" encoding="UTF-8"?>
<originalMessage>
    <id>123</id>
    <content><![CDATA[<message>
    <messageID>123</messageID>
    <order>abc</order>
    <price>123,45</price>
</message>]]></content>
</originalMessage>

And this XML can be stored in the database by the WSO2 Data Service without a problem as it complies with the XSD of the Data Service.

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