[WSO2 ESB]How to Aggregate 2 XMLs Based on a Element Value Using XSLT Mediator

The XSLT Mediator applies a specified XSLT transformation to a selected element of the current message payload.

Suppose you are getting 2 XML responses from 2 service endpoints like below.

summary.xml

   
 <?xml version="1.0" encoding="UTF-8"?>  
 <policyList xmlns="http://insurance.org/policyservice">  
   <policy>  
    <policyType>Life</policyType>  
    <holderName>Ann Frank</holderName>  
    <policyId>SWXU9124</policyId>  
    <premium>100000</premium>  
   </policy>  
   <policy>  
    <policyType>Life</policyType>  
    <holderName>Shane Watson</holderName>  
    <policyId>SWXABS4</policyId>  
    <premium>70000</premium>  
   </policy>  
 </policyList>  
   

detail.xml

   
 <?xml version="1.0" encoding="UTF-8"?>  
 <policyList xmlns="http://insurance.org/policyservice">  
   <policy>  
    <policyType>Life</policyType>  
    <policyId>SWXABS4</policyId>  
    <validityPeriod>3Years</validityPeriod>  
    <startedDate>10/10/2014</startedDate>  
    <claims>  
      <claim>  
       <id>2016AAASI900</id>  
       <date>01/06/2016</date>  
       <claimAmount>1400</claimAmount>  
      </claim>  
    </claims>  
   </policy>  
   <policy>  
    <policyType>Life</policyType>  
    <policyId>SWXU9124</policyId>  
    <validityPeriod>1Years</validityPeriod>  
    <startedDate>01/01/2016</startedDate>  
    <claims>  
      <claim>  
       <id>2016TABSI981</id>  
       <date>15/02/2016</date>  
       <claimAmount>9900</claimAmount>  
      </claim>  
    </claims>  
   </policy>  
 </policyList>  
   

Above two responses are dynamic responses. So, above 2 XMLs should be aggregated to one xml before applying XSLT mediator. For that you can use PayloadFactory Mediator, and get aggregated XML like below.

   
 <?xml version="1.0" encoding="UTF-8"?>  
 <policyList xmlns="http://insurance.org/policyservice">  
   <summary>  
    <policy>  
      <policyType>Life</policyType>  
      <holderName>Ann Frank</holderName>  
      <policyId>SWXU9124</policyId>  
      <premium>100000</premium>  
    </policy>  
    <policy>  
      <policyType>Life</policyType>  
      <holderName>Shane Watson</holderName>  
      <policyId>SWXABS4</policyId>  
      <premium>70000</premium>  
    </policy>  
   </summary>  
   <details>  
    <policy>  
      <policyType>Life</policyType>  
      <policyId>SWXABS4</policyId>  
      <validityPeriod>3Years</validityPeriod>  
      <startedDate>10/10/2014</startedDate>  
      <claims>  
       <claim>  
         <id>2016AAASI900</id>  
         <date>01/06/2016</date>  
         <claimAmount>1400</claimAmount>  
       </claim>  
      </claims>  
    </policy>  
    <policy>  
      <policyType>Life</policyType>  
      <policyId>SWXU9124</policyId>  
      <validityPeriod>1Years</validityPeriod>  
      <startedDate>01/01/2016</startedDate>  
      <claims>  
       <claim>  
         <id>2016TABSI981</id>  
         <date>15/02/2016</date>  
         <claimAmount>9900</claimAmount>  
       </claim>  
      </claims>  
    </policy>  
   </details>  
 </policyList>  
   

Assume you want to get the response as follows.

   
 <?xml version="1.0" encoding="UTF-8"?>  
 <ns:policyList xmlns:ns="http://insurance.org/policyservice">  
   <policy xmlns="http://insurance.org/policyservice">  
    <policyType>Life</policyType>  
    <holderName>Ann Frank</holderName>  
    <policyId>SWXU9124</policyId>  
    <premium>100000</premium>  
    <claims>  
      <claim>  
       <id>2016TABSI981</id>  
       <date>15/02/2016</date>  
       <claimAmount>9900</claimAmount>  
      </claim>  
    </claims>  
    <startedDate>01/01/2016</startedDate>  
    <validityPeriod>1Years</validityPeriod>  
   </policy>  
   <policy xmlns="http://insurance.org/policyservice">  
    <policyType>Life</policyType>  
    <holderName>Shane Watson</holderName>  
    <policyId>SWXABS4</policyId>  
    <premium>70000</premium>  
    <claims>  
      <claim>  
       <id>2016AAASI900</id>  
       <date>01/06/2016</date>  
       <claimAmount>1400</claimAmount>  
      </claim>  
    </claims>  
    <startedDate>10/10/2014</startedDate>  
    <validityPeriod>3Years</validityPeriod>  
   </policy>  
 </ns:policyList>  
   

You can use the XSLT mediator to above transformation. Use below XSL file with XSLT mediator. Upload following XSL file into registry.

merger.xslt

   
 <?xml version="1.0" encoding="UTF-8"?>  
 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:sn="http://insurance.org/policyservice" version="1.0">  
   <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes" />  
   <xsl:strip-space elements="*" />  
   <xsl:key name="policy-by-id" match="sn:details/sn:policy" use="sn:policyId" />  
   <!-- identity transform -->  
   <xsl:template match="@*|node()">  
    <xsl:copy>  
      <xsl:apply-templates select="@*|node()" />  
    </xsl:copy>  
   </xsl:template>  
   <xsl:template match="/sn:policyList">  
    <xsl:copy>  
      <xsl:apply-templates select="sn:summary/sn:policy" />  
    </xsl:copy>  
   </xsl:template>  
   <xsl:template match="sn:policy">  
    <xsl:copy>  
      <xsl:apply-templates />  
      <xsl:copy-of select="key('policy-by-id', sn:policyId)/sn:claims" />  
      <xsl:copy-of select="key('policy-by-id', sn:policyId)/sn:startedDate" />  
      <xsl:copy-of select="key('policy-by-id', sn:policyId)/sn:validityPeriod" />  
    </xsl:copy>  
   </xsl:template>  
 </xsl:stylesheet>  
   

Define XSLT mediator like this in your sequence

   
  <xslt key="gov:/xslt/merger.xslt"/>