Some Simple Updates To A DataPower XSLT stylesheet.

•Robert Broeckelmann

DataPowerSOAPWeb ServicesXSLTXML

In the last post, we saw how an XML Firewall in loopback mode could be used to return a valid SOAP response to a service message.  The stylesheet used simply returned a static SOAP response that was independent of the input parameters.  The stylesheet returns a response containing the sum of two numbers based upon this WSDL.  In this post, we’ll modify the original stylesheet to return a response that is the sum of the two input parameters: arg0 and arg1.

The original stylesheet looks like the following:

<xsl:stylesheet version=“1.0”
    xmlns:xsl=“http://www.w3.org/1999/XSL/Transform”
    xmlns:dp=”http://www.datapower.com/extensions”
    xmlns:dpfunc=“http://www.datapower.com/extensions/functions”
    xmlns:dpconfig=”http://www.datapower.com/param/config”
    xmlns:func=“http://exslt.org/functions”
    extension-element-prefixes=“dp func”
    exclude-result-prefixes=“dp dpfunc dpconfig func”> 
   
    <xsl:template match=“/”> 
          <soapenv:Envelope xmlns:soapenv=“http://schemas.xmlsoap.org/soap/envelope/“ xmlns:ws=”http://ws.rcbj.com/“>
            soapenv:Header/
            soapenv:Body
                ws:sumResponse
                    6
                </ws:sumResponse>
            </soapenv:Body>
        </soapenv:Envelope>
    </xsl:template>
</xsl:stylesheet>

We can extract the the input parameters, arg0 & arg1, when the following XPath expressions, respectively:

/*[local-name()= ‘Envelope’]/*[local-name()=’Body’]/*[local-name()=’sum’]/*[local-name()=’arg0′]/text()

/*[local-name()= ‘Envelope’]/*[local-name()=’Body’]/*[local-name()=’sum’]/*[local-name()=’arg1′]/text()

The following stylesheet elements will put the extracted values in variables called arg0 and arg1, respectively:

<xsl:variable name=“arg1” select=“/*[local-name()= ‘Envelope’]/*[local-name()=’Body’]/*[local-name()=’sum’]/*[local-name()=’arg0′]/text()”/>

<xsl:variable name=“arg2” select=“/*[local-name()= ‘Envelope’]/*[local-name()=’Body’]/*[local-name()=’sum’]/*[local-name()=’arg1′]/text()”/>

The sum of these two variables can be placed in a variable called sum with the following:

<xsl:variable name=“sum” select=“$arg1 + $arg2”/>

We can log the extracted values from the input message with the following:

<xsl:message dp:priority=“’warn’”>arg0: <xsl:value-of select=“$arg0”/></xsl:message>

<xsl:message dp:priority=“’warn’”>arg1: <xsl:value-of select=“$arg1”/></xsl:message>

We can reference the value of the sum variable with the following stylesheet element:

<xsl:value-of select=“$sum”/>

Putting all of this together, we have:

<xsl:stylesheet version=“1.0”
    xmlns:xsl=“http://www.w3.org/1999/XSL/Transform”
    xmlns:dp=”http://www.datapower.com/extensions”
    xmlns:dpfunc=“http://www.datapower.com/extensions/functions”
    xmlns:dpconfig=”http://www.datapower.com/param/config”
    xmlns:func=“http://exslt.org/functions”
    extension-element-prefixes=“dp func”
    exclude-result-prefixes=“dp dpfunc dpconfig func”> 
   
    <xsl:template match=“/”>
    <xsl:variable name=“arg1” select=“/*[local-name()= ‘Envelope’]/*[local-name()=’Body’]/*[local-name()=’sum’]/*[local-name()=’arg0′]/text()”/>
    <xsl:message dp:priority=“’warn’”>arg0: <xsl:value-of select=“$arg0”/></xsl:message>
    <xsl:variable name=“arg2” select=“/*[local-name()= ‘Envelope’]/*[local-name()=’Body’]/*[local-name()=’sum’]/*[local-name()=’arg1′]/text()”/>
     <xsl:message dp:priority=“’warn’”>arg1: <xsl:value-of select=“$arg1”/></xsl:message>
    <xsl:variable name=“sum” select=“$arg1 + $arg2”/>
        <soapenv:Envelope xmlns:soapenv=“http://schemas.xmlsoap.org/soap/envelope/“ xmlns:ws=”http://ws.rcbj.com/“>
            soapenv:Header/
            soapenv:Body
                ws:sumResponse
                    <xsl:value-of select=“$sum”/>
                </ws:sumResponse>
            </soapenv:Body>
        </soapenv:Envelope>
    </xsl:template>
</xsl:stylesheet>

For the following request message:

<soapenv:Envelope xmlns:soapenv=“http://schemas.xmlsoap.org/soap/envelope/“ xmlns:ws=”http://ws.rcbj.com/“>
   soapenv:Header/
   soapenv:Body
      ws:sum
         3
         4
      </ws:sum>
   </soapenv:Body>
</soapenv:Envelope>

This stylesheet will return a response containing:

<soapenv:Envelope xmlns:ws=“http://ws.rcbj.com/“ xmlns:soapenv=”http://schemas.xmlsoap.org/soap/envelope/“>
   soapenv:Header/
   soapenv:Body
      ws:sumResponse
         7
      </ws:sumResponse>
   </soapenv:Body>
</soapenv:Envelope>

So, we have made our service simulator a little smarter.

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