How to Split Messages and Aggregate Responses

This example scenario uses a back-end service with two stock quote inventories (IBM and SUN). A proxy service is configured in the Micro Integrator with the Iterate mediator (to split the incoming message) and the Aggregate mediator (to aggregate the responses).

When a stock quote request is received by the Micro Integrator, the proxy service will read the message payload and first identify the parts of the message that are intended for each of the inventories. The Iterate mediator will then split the message and route the parts to the relevant inventories in the backend. These messages will be processed asynchronously.

When the response messages are received from the backend, the Aggregate mediator will aggregate the responses into one and send to the client.

Synapse configuration

Listed below are the synapse configurations (proxy service) for implementing this scenario. See the instructions on how to build and run this example.

Proxy ServiceEndpoint

<?xml version="1.0" encoding="UTF-8"?>
<proxy name="SplitAggregateProxy" startOnLoad="true" transports="http https" xmlns="http://ws.apache.org/ns/synapse">
    <target>
        <inSequence>
            <iterate attachPath="//m0:getQuote" expression="//m0:getQuote/m0:request" preservePayload="true" xmlns:m0="http://services.samples">
                <target>
                    <sequence>
                        <header name="Action" action="set" scope="default" value="urn:getQuote"/>
                        <call>
                            <endpoint key="SimpleStockQuoteServiceEp"/>
                        </call>
                        <property name="enclose" scope="default" type="OM">
                            <ns:Results xmlns:ns="http://services.samples"/>
                        </property>
                    </sequence>
                </target>
            </iterate>
            <aggregate>
                <completeCondition timeout="0">
                    <messageCount max="-1" min="-1"/>
                </completeCondition>
                <onComplete aggregateElementType="root" enclosingElementProperty="enclose" expression="$body/*[1]">
                    <respond/>
                </onComplete>
            </aggregate>
        </inSequence>
        <faultSequence/>
    </target>
</proxy>

<?xml version="1.0" encoding="UTF-8"?>
<endpoint name="SimpleStockQuoteServiceEp" xmlns="http://ws.apache.org/ns/synapse">
    <address uri="http://localhost:9000/services/SimpleStockQuoteService">
        <suspendOnFailure>
            <initialDuration>-1</initialDuration>
            <progressionFactor>1</progressionFactor>
        </suspendOnFailure>
        <markForSuspension>
            <retriesBeforeSuspension>0</retriesBeforeSuspension>
        </markForSuspension>
    </address>
</endpoint>

Build and run

Create the artifacts:

1. Launch Visual Studio Code with the Micro Integrator for VS Code extension (MI for VS Code) installed.

   Info

   Follow the Install Micro Integrator for VS Code documentation for a complete installation guide.

2. Create an integration project.

3. Create the proxy service with the configurations given above.
4. Deploy the artifacts in your Micro Integrator.

Set up the back-end service:

1. Download the back-end service.
2. Extract the downloaded zip file.
3. Open a terminal, navigate to the axis2Server/bin/ directory inside the extracted folder.

4. Execute the following command to start the axis2server with the SimpleStockQuote back-end service:

   On MacOS/LinuxOn Windows

   sh axis2server.sh
   

   axis2server.bat
   

Invoke the sample proxy service:

HTTP method: POST 
Request URL: http://localhost:8290/services/SplitAggregateProxy
Content-Type: text/xml;charset=UTF-8
SOAPAction: "urn:mediate"
CustomHeader: application/json
Message Body:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
   <soapenv:Header/>
   <soapenv:Body>
   <m0:getQuote xmlns:m0="http://services.samples" xmlns:xsd="http://services.samples/xsd">
        <m0:request>
            <m0:symbol>IBM</m0:symbol>
        </m0:request>
        <m0:request>
            <m0:symbol>SUN</m0:symbol>
        </m0:request>
    </m0:getQuote>
   </soapenv:Body>
</soapenv:Envelope>

You can then observe that the response from the proxy service is the aggregated response received for each of the getQuote requests that were sent to the backend.

<?xml version='1.0' encoding='UTF-8'?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
    <soapenv:Body>
        <ns:Results xmlns:ns="http://services.samples">
            <ns:getQuoteResponse>
                <ns:return xmlns:ax21="http://services.samples/xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="ax21:GetQuoteResponse">
                    <ax21:change>-2.7541403681043874</ax21:change>
                    <ax21:earnings>13.316362583010434</ax21:earnings>
                    <ax21:high>-69.86552971310732</ax21:high>
                    <ax21:last>70.56563752927664</ax21:last>
                    <ax21:lastTradeTimestamp>Wed Jul 24 21:06:42 IST 2024</ax21:lastTradeTimestamp>
                    <ax21:low>-70.33199361844859</ax21:low>
                    <ax21:marketCap>3.731387687008923E7</ax21:marketCap>
                    <ax21:name>IBM Company</ax21:name>
                    <ax21:open>-69.18324170577428</ax21:open>
                    <ax21:peRatio>25.158635261126836</ax21:peRatio>
                    <ax21:percentageChange>4.1163339082481105</ax21:percentageChange>
                    <ax21:prevClose>-66.90760345232864</ax21:prevClose>
                    <ax21:symbol>IBM</ax21:symbol>
                    <ax21:volume>16901</ax21:volume>
                </ns:return>
            </ns:getQuoteResponse>
            <ns:getQuoteResponse>
                <ns:return xmlns:ax21="http://services.samples/xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="ax21:GetQuoteResponse">
                    <ax21:change>-2.401012800717323</ax21:change>
                    <ax21:earnings>12.160630064213766</ax21:earnings>
                    <ax21:high>197.42220037969906</ax21:high>
                    <ax21:last>189.55943936957652</ax21:last>
                    <ax21:lastTradeTimestamp>Wed Jul 24 21:06:42 IST 2024</ax21:lastTradeTimestamp>
                    <ax21:low>195.30882072296137</ax21:low>
                    <ax21:marketCap>5.364948639721981E7</ax21:marketCap>
                    <ax21:name>SUN Company</ax21:name>
                    <ax21:open>194.5745817372284</ax21:open>
                    <ax21:peRatio>-17.563343313834807</ax21:peRatio>
                    <ax21:percentageChange>1.328464451789101</ax21:percentageChange>
                    <ax21:prevClose>-180.73594648948068</ax21:prevClose>
                    <ax21:symbol>SUN</ax21:symbol>
                    <ax21:volume>17559</ax21:volume>
                </ns:return>
            </ns:getQuoteResponse>
        </ns:Results>
    </soapenv:Body>
</soapenv:Envelope>