Mule ESB Example

Example: Hello World

In this example, we will create a simple Mule application to implement the following flow:



The flow accepts HTTP requests, sets a payload on the message, applies some transformation on the payload, and finally returns a response to the end user.
So we will use  :

• HTTP endpoint : it allows, in the beginning of the flow, to receive request from the end user, and, in the end of the flow, to return the message as response to the end user.
• Java Transformer : to apply a custom transformation on the payload : "Hello " + {payload}
• Echo component : to display the message payload.

1. Technologies used

• Anypoint Studio
• JDK 1.7

2. Mule XML Editor

The following is the flow in XML representation:

<?xml version="1.0" encoding="UTF-8"?>

<mule 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" version="EE-3.5.0"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="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">

    <flow name="mulehelloworldexampleFlow1" doc:name="mulehelloworldexampleFlow1">

        <http:inbound-endpoint exchange-pattern="request-response"

            host="localhost" port="8081" doc:name="HTTP" />

        

        <custom-transformer class="com.keylesson.transformer.KeyTransformer"

            doc:name="Key Transformer" />

        

        <echo-component doc:name="Echo" />

    </flow>

</mule>

3. Java Transformer

To apply a custom transformation on the message payload, we have used Java Transformer.

The following is the class called by the Java Transformer :

package com.keylesson.transformer;

import org.mule.api.transformer.TransformerException;

import org.mule.transformer.AbstractTransformer;

public class KeyTransformer extends AbstractTransformer {

    @Override

    protected Object doTransform(Object src, String enc)

            throws TransformerException {

        return "Hello " + src.toString().substring(1);

    }

}

<?xml version="1.0" encoding="UTF-8"?><mule 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" version="EE-3.5.0