Custom Aggregator in Mule

  Custom Aggregator in Mule

Aggregator is used to reassemble the parts of the original message.In Custom Aggregator we can write our own aggregator by java class.

flow of custom aggregator

In below example XML input payload is splitted and stored in a folder and custom aggregator finally aggregates the data again in original form.



Custom aggregator configuration :

Just we need to give path of java class in which we have written aggregator logic.



Custom Aggregator java class located in src/main/java

package test_customagg;

import org.mule.api.MuleContext;
import org.mule.routing.AbstractAggregator;
import org.mule.routing.correlation.EventCorrelatorCallback;
import org.mule.DefaultMuleEvent;
import org.mule.DefaultMuleMessage;
import org.mule.api.MuleContext;
import org.mule.api.MuleEvent;
import org.mule.api.store.ObjectStoreException;
import org.mule.api.transformer.TransformerException;
import org.mule.routing.AbstractAggregator;
import org.mule.routing.AggregationException;
import org.mule.routing.EventGroup;
import org.mule.routing.correlation.CollectionCorrelatorCallback;
import org.mule.routing.correlation.EventCorrelatorCallback;
import org.mule.util.concurrent.ThreadNameHelper;

import java.util.Iterator;

public class TestAggregator extends AbstractAggregator
{

@Override
    protected EventCorrelatorCallback getCorrelatorCallback(MuleContext muleContext)
    {
        return new CollectionCorrelatorCallback(muleContext,storePrefix)
        {
            @Override
            public MuleEvent aggregateEvents(EventGroup events) throws AggregationException
            {
                StringBuffer buffer = new StringBuffer(128);

                try
                {
                    for (Iterator<MuleEvent> iterator = events.iterator(); iterator.hasNext();)
                    {
                        MuleEvent event = iterator.next();
                        try
                        {
                           buffer.append(event.transformMessageToString());
                        }
                        catch (TransformerException e)
                        {
                            throw new AggregationException(events, null, e);
                        }
                    }
                }
                catch (ObjectStoreException e)
                {
                    throw new AggregationException(events,null,e);
                }

                logger.debug("event payload is: " + buffer.toString());
                return new DefaultMuleEvent(new DefaultMuleMessage
                  (buffer.toString(), muleContext), events.getMessageCollectionEvent());
            }
        };
    }
}

URL : http://localhost:8085/api/customagg

Method : POST

Input :

<Employees> <Employee> <FirstName>Himanshu</FirstName> <LastName>Pal</LastName> <Salary>120000</Salary> </Employee> <Employee> <FirstName>Sonam</FirstName> <LastName>Sharma</LastName> <Salary>200000</Salary> </Employee> <Employee> <FirstName>Piyush</FirstName> <LastName>Joshi</LastName> <Salary>300000</Salary> </Employee> <Employee> <FirstName>Vinod</FirstName> <LastName>Shukla</LastName> <Salary>800000</Salary> </Employee> <Employee> <FirstName>Kunal</FirstName> <LastName>Verma</LastName> <Salary>500000</Salary> </Employee> </Employees>

Output :

XML project code :


<?xml version="1.0" encoding="UTF-8"?> <mule xmlns:mulexml="http://www.mulesoft.org/schema/mule/xml" xmlns:file="http://www.mulesoft.org/schema/mule/file" xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:spring="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mulesoft.org/schema/mule/xml http://www.mulesoft.org/schema/mule/xml/current/mule-xml.xsd http://www.mulesoft.org/schema/mule/file http://www.mulesoft.org/schema/mule/file/current/mule-file.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd"> <http:listener-config name="HTTP_Listener_Configuration" host="0.0.0.0" port="8085" basePath="/api" doc:name="HTTP Listener Configuration"/> <file:connector name="File" writeToDirectory="src/main/resources/splitted" autoDelete="true" streaming="true" validateConnections="true" doc:name="File"/> <flow name="test_customaggFlow"> <http:listener config-ref="HTTP_Listener_Configuration" path="/customagg" doc:name="HTTP"/> <splitter expression="#[xpath('//Employee')]" doc:name="Splitter"/> <mulexml:dom-to-xml-transformer doc:name="DOM to XML"/> <file:outbound-endpoint path="src/main/resources/splitted" connector-ref="File" responseTimeout="10000" doc:name="File"/> <custom-aggregator failOnTimeout="true" class="test_customagg.TestAggregator" doc:name="Custom Aggregator"/> <mulexml:dom-to-xml-transformer doc:name="DOM to XML"/> </flow> </mule>