Working with ESB XSLT Mediator

What is ESB XSLT Mediator ? 

ESB XLST Mediator supports mediates the messages  when there are dynamic (not predefined/ not static) request for  ESB proxy. The XLST  mediator applies specified XLST transformation to a selected element of current message payload.

Working with XSLT Mediator

This blog post explains how XSLT mediator works, with a simple example.

Let's assume we have a simple calculator service which defines to  work only for "a" and "b" payloads for all four  operations. Assume this service is hosted in WSO2 Application server.

<add>
         <a>?</a>
         <b>?</b>
 </add>

<divide>        
         <a>?</a>
         <b>?</b>
</divide>

<multiply>        
         <a>?</a>
         <b>?</b>
</multiply>

<subtract>
         <a>?</a>
         <b>?</b>
 </subtract>

But what happens if we give payloads as "c" and "d" ? The calculator service won't identify the payloads and give us error response. As a solution for this we can use  ESB XSLT mediator.

This is the created XSLT file for solve  the above problem and save that in ESB local entries.

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:p="http://ws.myeclipseide.com" version="1.0">
      <xsl:output method="xml" encoding="utf-8" indent="yes"></xsl:output>
      <xsl:template match="p:add">
         <p:addition xmlns="http://ws.apache.org/ns/synapse">
            <p:c>
               <xsl:value-of select="p:a"></xsl:value-of>
            </p:c>
            <p:d>
               <xsl:value-of select="p:b"></xsl:value-of>
            </p:d>
         </p:addition>
      </xsl:template>
   </xsl:stylesheet>

Please note this XSLT  representation only for "add" operation.

Create a proxy service in ESB by adding XSLT mediator as follows.

<?xml version="1.0" encoding="UTF-8"?>
<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="testR"
       transports="https,http"
       statistics="disable"
       trace="disable"
       startOnLoad="true">
   <target>
      <inSequence>
         <xslt key="xsltNew"/>
         <send>
            <endpoint>
               <address uri="http://localhost:8280/services/Calculator/"/>
            </endpoint>
         </send>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
   </target>
   <publishWSDL uri="http://localhost:9764/services/Calculator?wsdl"/>
   <description/>
</proxy>

Now create a new project in SoapUI by adding the WSDL of the created calculator  service.

Invoke the calculator service by sending the payloads as "c" and "d". Now the requests are receiving to ESB as "c" and "d" . The XSLT mediator in ESB proxy converts this to "a"and "b" and send to the Application server where the calculator service is hosted. Inside Application  server the calculations are  done and the respond is send back to the ESB. Then the XSLT mediator in ESB Proxy service understands that, this is the the response for "c" and "d" and it send the answer to the client.

How to get a JSON response for XML request using SoapUI

This is a small tip on how to  get a JSON response from XML request while you are working with soapUI.

1. Download and start the latest version of Application server. (at the moment its 5.2.1) . In order to get the JSON response you need to change the following configurations.

2.Add following parameter to 'axis2_client.xml' in AppServer_HOME}/repository/conf/axis2/' directory. because the default is set to false.

'<parameter name="httpContentNegotiation">true</parameter>'

3. Now restart the server.

4. Deploy the Jaxrs_Basic service to simulate this.

5.Open SoapUI and create a new project for Jaxrs_Basic service.

6. Now the new REST project is created and you need to set the  media type to "application /xml"

7. Add header name value pairs  Name :" Accept" Value :"application/json"

 

you can see the converted response to JSON.

8.Same as you can convert the JSON request to XML

How to capture SOAP / XML messages with WireShark

When you are debugging a web service calls some times you may want to capture requests and responses . Using WireShark you can see exactly what requests are coming and what are the responses are going out from service. This blog explains how to capture SOAP /XML  message using wire shark.

First you need to start a web service in your machine. Here the used service is Jaxrs_Basic and deploy it in your machine.

1. Open SOAP UI , get the WADL of Jaxrs_Basic service and create a new SOAP UI project.

2. Open WireShark in your machine giving “sudo wireshark”

3. Create a “ Capture Filter” as follows.

• Select Capture from menu bar → Interfaces → Select your interface where your web service is running
• Click options on “Capture Interface Menu”-> It will direct you to “wireshark capture options” window.
• Click on the selected interface and it directs to the edit interface settings window.
• Set your capture filter as display in screen shot.
  
  

4.Enable network name resolution (makes identifying traffic much easier)

Now we are ready to capture required packets.

5. Invoke the Jaxrs_Basic service using SOAP UI.

6. Here you can see packets are receiving through WireShark.

7. Now you need to filter the SOAP/XML messages. To do this just type the filter “xml” at filter box and click at Apply. This will capture the soap messages in invoked web service.

8. Select one message-> right click on it ->”Select follow TCP Stream” from available menu.

9. You can view the soap/xml  message clearly.