Add a very basic pom.xml file to your new Maven project as follows:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>sample</groupId>

    <artifactId>gadget</artifactId>

    <packaging>war</packaging>

    <version>1.0</version>

    <name>Hello Gadget sample</name>

    <build>

        <finalName>hello-gadget</finalName>

    </build>

</project>

Add a very basic web.xml file to the src/main/webapp/WEB-INF directory of your project:

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

<web-app version="3.0" metadata-complete="true"

 xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

    <display-name>hello-gadget</display-name>

</web-app>

Add the following content to the HelloGadget.xml under the src/main/webapp/gadgets/HelloGadget directory:

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

<Module>

  <ModulePrefs author="eXoPlatform" 

               title="Hello World"

               directory_title="Hello World"

               description="The simplest gadget">

  </ModulePrefs>

  

  <Content type="html">

  <![CDATA[

    <div class='hello'>

      <h2>Hello</h2>

      <h6>Welcome to Hello World gadget!</h6>

      <p><i>Powered by eXo Platform.</i></p>

    </div>

  ]]>

  </Content>

</Module>

Add the following content to the gadget.xml file under the src/main/webapp/WEB-INF directory:

<gadgets

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

    xsi:schemaLocation="http://www.gatein.org/xml/ns/gatein_objects_1_0 http://www.gatein.org/xml/ns/gadgets_1_0"

    xmlns="http://www.gatein.org/xml/ns/gadgets_1_0">

  <gadget name="HelloGadget">

    <path>/gadgets/HelloGadget/HelloGadget.xml</path>

  </gadget>

</gadgets>

Create the target war with the Maven command: mvn clean install.

Follow custom-extension section to create custom-extension-config.jar that declares the hello-gadget.war as a portal dependency.

Deploy the hello-gadget.war and custom-extension-config.jar files into the deployment folders where you unpacked the eXo Platform installation.

Select Administration → Applications, then add this gadget into a specific category to bring it in use:

Go to the Dashboard to insert the gadget in the page. Open the Dashboard Workspace by clicking the Add Gadgets link and choose the Hello World gadget. The result is as below: