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Load Balancing with Message Forwarding Processor

This example demonstrates how the message forwarding processor handles load balancing.

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.

Proxy Service

<proxy xmlns="http://ws.apache.org/ns/synapse" name="StockQuoteProxy"
              transports="https http"
              startOnLoad="true">
    <description/>
    <target>
       <inSequence>
          <property name="FORCE_SC_ACCEPTED" value="true" scope="axis2"/>
          <property name="OUT_ONLY" value="true"/>
          <store messageStore="JMSMS"/>
       </inSequence>
       <outSequence/>
       <faultSequence/>
    </target>
 </proxy>

Endpoint 1

<endpoint xmlns="http://ws.apache.org/ns/synapse" name="SimpleStockQuoteService1">
  <address uri="http://localhost:9001/services/SimpleStockQuoteService"/>
</endpoint>

Endpoint 2

<endpoint xmlns="http://ws.apache.org/ns/synapse" name="SimpleStockQuoteService2">
  <address uri="http://localhost:9002/services/SimpleStockQuoteService"/>
</endpoint>

Endpoint 3

<endpoint xmlns="http://ws.apache.org/ns/synapse" name="SimpleStockQuoteService3">
  <address uri="http://localhost:9003/services/SimpleStockQuoteService"/>
</endpoint>

Message Store

<messageStore xmlns="http://ws.apache.org/ns/synapse" class="org.apache.synapse.message.store.impl.jms.JmsStore" name="JMSMS">
  <parameter name="java.naming.factory.initial">org.apache.activemq.jndi.ActiveMQInitialContextFactory</parameter>
  <parameter name="store.jms.cache.connection">false</parameter>
  <parameter name="java.naming.provider.url">tcp://localhost:61616</parameter>
  <parameter name="store.jms.JMSSpecVersion">1.1</parameter>
  <parameter name="store.jms.destination">JMSMS</parameter>
</messageStore>

Message Processor 1

<messageProcessor xmlns="http://ws.apache.org/ns/synapse" class="org.apache.synapse.message.processor.impl.forwarder.ScheduledMessageForwardingProcessor"
                         name="Forwarder1"
                         targetEndpoint="SimpleStockQuoteService1"
                         messageStore="JMSMS">
  <parameter name="client.retry.interval">1000</parameter>
  <parameter name="interval">1000</parameter>
  <parameter name="is.active">true</parameter>
</messageProcessor>

Message Processor 2

<messageProcessor xmlns="http://ws.apache.org/ns/synapse" class="org.apache.synapse.message.processor.impl.forwarder.ScheduledMessageForwardingProcessor"
                         name="Forwarder2"
                         targetEndpoint="SimpleStockQuoteService2"
                         messageStore="JMSMS">
  <parameter name="client.retry.interval">1000</parameter>
  <parameter name="interval">1000</parameter>
  <parameter name="is.active">true</parameter>
</messageProcessor>

Message Processor 3

<messageProcessor xmlns="http://ws.apache.org/ns/synapse" class="org.apache.synapse.message.processor.impl.forwarder.ScheduledMessageForwardingProcessor"
                         name="Forwarder3"
                         targetEndpoint="SimpleStockQuoteService3"
                         messageStore="JMSMS">
  <parameter name="client.retry.interval">1000</parameter>
  <parameter name="interval">1000</parameter>
  <parameter name="is.active">true</parameter>
</messageProcessor>

Build and run

Create the artifacts:

1. Set up ESB Integration Studio.
2. Create an integration project with an ESB Configs module and an Composite Exporter.
3. Create the proxy service, endpoints, message stores and message processors with the configurations given above.
4. Deploy the artifacts in your Micro Integrator.

Configure the ActiveMQ broker.

You can analyze the message sent by the Micro Integrator to the secure service using TCPMon.

On successful execution of the placeorder request, you will see the following message on the back-end:

Sun Aug 18 10:58:00 IST 2013 samples.services.SimpleStockQuoteService :: Accepted order #5 for : 18851 stocks of WSO2 at $ 61.782478265721714

If you send the placeorder request to the proxy service several times and observe the log on the back-end server, you will see that the messages are distributed among the back-end nodes.

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