Sample 15: Using the Enrich Mediator for Message Copying and Content Enrichment

Introduction

This sample demonstrates how to copy message content to a property as well as how to enrich a message from a given source.

Prerequisites

For a list of prerequisites, see prerequisites for starting the ESB Samples.

Building the sample

The XML configuration for this sample is as follows: 

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://ws.apache.org/ns/synapse">
    <sequence name="main">
        <in>
            <enrich>
                <source type="custom"
                        xpath="//m0:getQuote/m0:request/m0:symbol/text()"
                        xmlns:m0="http://services.samples"/>
                <target type="property" property="ORIGINAL_REQ"/>
            </enrich>
            <enrich>
                <source type="body"/>
                <target type="property" property="REQUEST_PAYLOAD"/>
            </enrich>

            <enrich>
                <source type="inline" key="init_req"/>
                <target xmlns:m0="http://services.samples"
                        xpath="//m0:getQuote/m0:request/m0:symbol/text()"/>
            </enrich>
            <send>
                <endpoint>
                    <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
                </endpoint>
            </send>
            <drop/>
        </in>
        <out>
            <header xmlns:urn="http://synapse.apache.org" name="urn:lastTradeTimestamp" value="foo"/>
            <enrich>
                <source type="custom"
                        xpath="//ns:getQuoteResponse/ns:return/ax21:lastTradeTimestamp"
                        xmlns:ns="http://services.samples"
                        xmlns:ax21="http://services.samples/xsd"/>
                <target xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
                        xmlns:urn="http://synapse.apache.org"
                        xpath="/soapenv:Envelope/soapenv:Header/urn:lastTradeTimestamp"/>
            </enrich>
             <log level="full"/>
            <log>
                <property name="Original Request Symbol" expression="get-property('ORIGINAL_REQ')"/>
                <property name="Request Payload" expression="get-property('REQUEST_PAYLOAD')"/>
            </log>
            <send/>
        </out>
    </sequence>
    <localEntry key="init_req">MSFT</localEntry>
    <localEntry key="price_req">
        <m0:symbol xmlns:m0="http://services.samples">MSFT</m0:symbol>
    </localEntry>
</definitions>

This configuration file  synapse_sample_15.xml is available in the <EI_HOME>/samples/service-bus directory. 

To build the sample

1. Start the ESB with the sample 15 configuration. For instructions on starting a sample ESB configuration, see Starting the ESB with a sample configuration.
   
   The operation log keeps running until the server starts, which usually takes several seconds. Wait until the server has fully booted up and displays a message similar to "WSO2 Carbon started in n seconds."

2. Start the Axis2 server. For instructions on starting the Axis2 server, see Starting the Axis2 server.

3. Deploy the back-end service SimpleStockQuoteService. For instructions on deploying sample back-end services, see Deploying sample back-end services.

   Now you have a running ESB instance and a back-end service deployed. In the next section, we will send a message to the back-end service through the ESB using a sample client.

Executing the sample

The sample client used here is the Stock Quote Client, which can operate in several modes. For further details on this sample client and its operation modes, see Stock Quote Client.

To execute the sample client

• Run the following command from the <EI_HOME>/samples/axis2Client directory.

  ant stockquote -Dtrpurl=http://localhost:8280/services/StockQuote

Analyzing the output

When you analyze the debug log output on the ESB console, you will see that the original IBM request is changed to MSFT using the enrich mediator.

According to the configuration file synapse_sample_15.xml, the original payload and the symbol is stored as synapse properties. Once the reply comes to synapse, the lastTradeTimestamp value of the response is added as a soap header in order to show the functionality of the enrich mediator. Also the request payload and request symbol values are logged in the out sequence.

Different parts of the message are stored in or copied to properties inside the in-sequence. Just before sending the message to the a back-end service the request value is modified based on the local entry.  Then in the out-sequence, the enrich mediator is used to enrich the soap header based on the lastTradeTimestamp value of the response.