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Using the Message Sampling Processor¶

This example demonstrates the usage of the message sampling processor.

Synapse configuration¶

Following are the artifact configurations that we can use to implement this scenario. See the instructions on how to build and run this example.

Send Sequence

<sequence xmlns="http://ws.apache.org/ns/synapse" name="send_seq">
    <send>
        <endpoint>
            <address uri="http://localhost:9000/services/SimpleStockQuoteService">
                <suspendOnFailure>
                <errorCodes>-1</errorCodes>
                <progressionFactor>1.0</progressionFactor>
                </suspendOnFailure>
            </address>
        </endpoint>
    </send>
</sequence>

Proxy Service

<proxy xmlns="http://ws.apache.org/ns/synapse" name="StockQuoteProxy" transports="https http" startOnLoad="true" trace="disable">
          <description />
    <target>
       <inSequence>
            <log level="full"/>
            <property name="FORCE_SC_ACCEPTED" value="true" scope="axis2"/>
            <property name="OUT_ONLY" value="true"/>
            <store messageStore="MyStore"/>
        </inSequence>
        <outSequence>
             <send />
        </outSequence>
    </target>
</proxy>

Message Store

<messageStore xmlns="http://ws.apache.org/ns/synapse" name="MyStore"/>

Message Processor

<messageProcessor xmlns="http://ws.apache.org/ns/synapse"
     class="org.apache.synapse.message.processor.impl.sampler.SamplingProcessor"
     name="SamplingProcessor" messageStore="MyStore">
    <parameter name="interval">20000</parameter>
    <parameter name="sequence">send_seq</parameter>
    <parameter name="is.active">true</parameter>
</messageProcessor>

Build and run¶

Create the artifacts:

Set up ESB Integration Studio.
Create an integration project with an ESB Configs module and an Composite Exporter.
Create the proxy service, mediation sequences, message store, and message processor with the configurations given above.
Deploy the artifacts in your Micro Integrator.

Configure the ActiveMQ broker and set up the JMS Sender.

Set up the back-end service:

Download the back-end service.
Extract the downloaded zip file.
Open a terminal, navigate to the axis2Server/bin/ directory inside the extracted folder.
Execute the following command to start the axis2server with the SimpleStockQuote back-end service:
On MacOS/Linux/CentOS
```
sh axis2server.sh
```
On Windows
```
axis2server.bat
```

Send the following request to invoke the service:

POST http://localhost:9090/services/StockQuoteProxy HTTP/1.1
Accept-Encoding: gzip,deflate
Content-Type: text/xml;charset=UTF-8
SOAPAction: "urn:getQuote"
Content-Length: 492
Host: localhost:9090
Connection: Keep-Alive
User-Agent: Apache-HttpClient/4.1.1 (java 1.5)

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ser="http://services.samples" xmlns:xsd="http://services.samples/xsd">
   <soapenv:Header/>
   <soapenv:Body>
      <ser:getQuote xmlns:ser="http://services.samples" xmlns:xsd="http://services.samples/xsd">
         <ser:request>
            <xsd:symbol>IBM</xsd:symbol>
         </ser:request>
      </ser:getQuote>
   </soapenv:Body>
</soapenv:Envelope>

When you send the request, the message will be dispatched to the proxy service. In the proxy service, the store mediator will store the getQuote request message in the "MyStore" message store. The message processor will consume the messages, and forward them to the "send_seq" sequence in configured rate. You will observe that the service invocation rate is not changing when we increase the rate of proxy service invocation.

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