How to use Java scrip mediator to modify outgoing message body during mediation flow - WSO2 ESB/ API Manager

Here in this post we will see how we can use Java scrip mediator to modify outgoing message body during mediation flow.

Below is the sample API configuration i used for this sample. As you can see here i will extract password field from incoming message and send it as symbol to back end service. Since i need to check what actually pass to back end server i added TCPMon between gateway and back end server. That is why 8888 port is appear there. 

  <api name="TestAPI" context="/test">
      <resource methods="POST" url-mapping="/status" faultSequence="fault">
         <inSequence>
            <script language="js">var symbol = mc.getPayloadXML()..*::password.toString();
               mc.setPayloadXML(
                  &lt;m:getQuote xmlns:m="http://services.samples/xsd"&gt;
                     &lt;m:request&gt;
                        &lt;m:symbol&gt;{symbol}&lt;/m:symbol&gt;
                     &lt;/m:request&gt;
                  &lt;/m:getQuote&gt;);</script>
            <send>
               <endpoint name="test-I_APIproductionEndpoint_0">
                  <http uri-template="http://127.0.0.1:8888/"/>
               </endpoint>
            </send>
         </inSequence>
         <outSequence>
            <send/>
         </outSequence>
      </resource>
   </api>

Then i send request as follows. As you can see here password will have some data and i'm sending post request.

curl -v -X POST -H "Content-Type: application/json" -d '{"username":"xyz","password":"xyz & abc"}' http://127.0.0.1:8280/test/status

I can see my values pass to back end properly. Since i added TCPMon between ESB and back end to verify out going message i can see what going out from ESB. Also following is wore logs captured for my message.

[2016-08-10 14:30:21,236] DEBUG - wire >> "POST /test/status HTTP/1.1[\r][\n]"
[2016-08-10 14:30:21,236] DEBUG - wire >> "Host: 127.0.0.1:8280[\r][\n]"
[2016-08-10 14:30:21,236] DEBUG - wire >> "User-Agent: curl/7.43.0[\r][\n]"
[2016-08-10 14:30:21,236] DEBUG - wire >> "Accept: */*[\r][\n]"
[2016-08-10 14:30:21,236] DEBUG - wire >> "Content-Type: application/json[\r][\n]"
[2016-08-10 14:30:21,236] DEBUG - wire >> "Content-Length: 41[\r][\n]"
[2016-08-10 14:30:21,237] DEBUG - wire >> "[\r][\n]"
[2016-08-10 14:30:21,237] DEBUG - wire >> "{"username":"xyz","password":"xyz & abc"}"
[2016-08-10 14:30:21,245] DEBUG - wire << "POST /status HTTP/1.1[\r][\n]"
[2016-08-10 14:30:21,245] DEBUG - wire << "Content-Type: application/json[\r][\n]"
[2016-08-10 14:30:21,246] DEBUG - wire << "Accept: */*[\r][\n]"
[2016-08-10 14:30:21,246] DEBUG - wire << "Transfer-Encoding: chunked[\r][\n]"
[2016-08-10 14:30:21,246] DEBUG - wire << "Host: 127.0.0.1:8888[\r][\n]"
[2016-08-10 14:30:21,246] DEBUG - wire << "Connection: Keep-Alive[\r][\n]"
[2016-08-10 14:30:21,246] DEBUG - wire << "User-Agent: Synapse-PT-HttpComponents-NIO[\r][\n]"
[2016-08-10 14:30:21,246] DEBUG - wire << "[\r][\n]"
[2016-08-10 14:30:21,246] DEBUG - wire << "2f[\r][\n]"
[2016-08-10 14:30:21,247] DEBUG - wire << "{"getQuote":{"request":{"symbol":"xyz & abc"}}}[\r][\n]"
[2016-08-10 14:30:21,247] DEBUG - wire << "0[\r][\n]"
[2016-08-10 14:30:21,247] DEBUG - wire << "[\r][\n]"

TCPMon output.