Eddú Meléndez

How to Start With Mule ESB

What is an ESB?

It’s a software architecture. ESB or Enterprise Service Bus is a Enterprise Integration Pattern (EIP) solves the spaghetti integration pattern.

What is Mule ESB?

It is a Open Source Enterprise Service Bus (ESB), which allow to integrate lot of technologies.

Mule main parts:

  • Component
  • Transport
  • Transformers
  • Inbound/Outbound Routers

Mule also provide rich set of:

  • Routers
  • Transformers
  • Filters

Using Maven

Make sure you have set the Mulesoft’s repository in settings.xml

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<repositories>
  <repository>
    <id>mulesoft-release</id>
    <name>Mulesoft Release Repository</name>
    <url>https://repository.mulesoft.org/nexus/content/repositories/public/</url>
  </repository>
</repositories>

Also, check you have the pluginGroup org.mule.tools.

Now, you are able to run the following command your terminal:

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mvn mule-project-archetype:create -DartifactId=helloWorld -DmuleVersion=3.5.0

Using Gradle

Make sure you have a build.gradle file inside the folder with the following content:

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buildscript {
    dependencies {
        classpath group: 'org.mulesoft.build', name: 'mule-gradle-plugin', version: '1.1.0'
    }

    repositories {
        maven {
            url 'http://repository.mulesoft.org/releases'
        }
    }
}

apply plugin: 'mule'

mule.version = '3.5.0'

mule.muleEnterprise = false

After that you can execute:

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gradle initMuleProject

By default, mule.muleEnterprise is set to true.

For more information you can visit mule-gradle-plguin documentation.

Using maven or gradle you will be able to see the project like this

Differences between maven and gradle plugin

Maven Gradle
Provide mule packaging Provide mule plugin
Allow to deploy in local mule standalone Allow to deploy in local mule standalone, Mule Management Console and Cloudhub
- Allow to run application with a simple command

Testing

mule-config.xml is placed inside of src/main/app. Here you will find a http service which will return Hello World! message.

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<?xml version="1.0" encoding="UTF-8"?>
<!-- created by the gradle mule plugin -->

<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-3.4.2" 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="mule-configFlow1" doc:name="mule-configFlow1">
    <http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8081" doc:name="HTTP"/>
    <set-payload doc:name="Set Payload" value="Hello World!"/>
  </flow>
</mule>

Then, proceed to write a test for the existing flow. As you can see response will be validated.

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import org.hamcrest.core.Is;
import org.junit.Assert;
import org.junit.Test;
import org.mule.api.MuleMessage;
import org.mule.api.client.MuleClient;
import org.mule.tck.junit4.FunctionalTestCase;

public class MuleTest extends FunctionalTestCase {

  @Override
  protected String getConfigFile() {
    return "src/main/app/mule-config.xml";
  }

  @Test
  public void testMuleConfigFlow1() throws Exception {
    MuleClient client = muleContext.getClient();
    MuleMessage message = client.request("http://localhost:8081", 3000L);
    String payload = message.getPayloadAsString();
    Assert.assertThat(payload, Is.is("Hello World!"));
  }
}

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