Using a Parent Plugin Project

Maven supports project inheritance. You can create a parent project that contains properties child projects have in common, and child projects inherit those properties from the parent project. This saves time, since you don’t need to specify those properties in each project. If you develop more than one project, it makes sense to leverage project inheritance so that all projects can share properties they have in common.

Our example demonstrates project inheritance; we’ll build a project with a parent/child relationship. Even if you’re not going to leverage Maven’s project inheritance capabilities when you build your Liferay plugins with Maven, the process is the same for creating any Liferay plugin with Maven’s Liferay artifacts. For more information on project inheritance, see Maven’s documentation at http://maven.apache.org/pom.html#Inheritance.

Let’s create our parent project, and then specify the general settings you’ll need to build your plugins for Liferay. The parent project is similar to the project root of the Liferay Plugins SDK. Its pom.xml file can specify information to be used by any plugin projects that refer to it. You can always specify information in each plugin’s POM, but it’s more convenient to use the parent project’s POM for sharing common information.

Let’s create a parent project named sample-parent-project:

1. Create a new directory for your parent project. For this example, we’ll name the directory sample-parent-project. You can place the directory anywhere on your file system.

2. Inside the sample-parent-project directory, create a pom.xml file and insert the following lines:

   <?xml version="1.0" encoding="UTF-8"?>
   <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/xsd/maven-4.0.0.xsd">
       <modelVersion>4.0.0</modelVersion>
   
       <groupId>com.liferay.sample</groupId>
       <artifactId>sample-parent-project</artifactId>
       <version>1.0-SNAPSHOT</version>
       <packaging>pom</packaging>
   
       <name>sample-parent-project</name>
       <url>http://www.liferay.com</url>
   
       <properties>
           <liferay.auto.deploy.dir>${liferay.auto.deploy.dir}</liferay.auto.deploy.dir>
           <liferay.version>${liferay.version}</liferay.version>
       </properties>
   
       <dependencies>
           <dependency>
               <groupId>com.liferay.portal</groupId>
               <artifactId>portal-client</artifactId>
               <version>6.1.30</version>
           </dependency>
           <dependency>
               <groupId>com.liferay.portal</groupId>
               <artifactId>portal-impl</artifactId>
               <version>6.1.30</version>
               <scope>provided</scope>
           </dependency>
           <dependency>
               <groupId>com.liferay.portal</groupId>
               <artifactId>portal-service</artifactId>
               <version>6.1.30</version>
               <scope>provided</scope>
           </dependency>
           <dependency>
               <groupId>com.liferay.portal</groupId>
               <artifactId>portal-web</artifactId>
               <version>6.1.30</version>
               <type>war</type>
               <scope>provided</scope>
           </dependency>
           <dependency>
               <groupId>com.liferay.portal</groupId>
               <artifactId>util-bridges</artifactId>
               <version>6.1.30</version>
           </dependency>
           <dependency>
               <groupId>com.liferay.portal</groupId>
               <artifactId>util-java</artifactId>
               <version>6.1.30</version>
           </dependency>
           <dependency>
               <groupId>com.liferay.portal</groupId>
               <artifactId>util-taglib</artifactId>
               <version>6.1.30</version>
           </dependency>
       </dependencies>
   
   </project>
   

   If you use this example POM, replace the <version> values with the version of Liferay applicable to the plugins you’re developing.

   You can also specify these key properties in your Global or User settings.xml file. To learn more about this method, visit the Configuring Your Liferay Maven Project section.

3. Modify the values of the properties to match your Liferay environment.

   Fill in the <liferay.auto.deploy.dir>...</liferay.auto.deploy.dir> tags with the path of your Liferay bundle’s deploy directory. This is the auto-deploy directory you will eventually copy your plugin to deploy on Liferay.

   Fill in the <liferay.version>...</liferay.version> tags with the version of Liferay you are using.

   Your POM’s properties should look similar to the following:

   <properties>
       <liferay.auto.deploy.dir>E:\liferay-portal-6.1.30-ee-ga3\deploy</liferay.auto.deploy.dir>
       <liferay.version>6.1.30</liferay.version>
   </properties>
   

By specifying your Liferay instance’s deploy directory in the POM, you’re telling Maven exactly where to deploy your plugin artifacts.

Your parent project now specifies common dependencies on required Liferay Maven artifacts. All your parent project’s modules (i.e., projects that refer to this parent) can leverage these dependencies.

Note: You could just as easily include such dependencies in the POM of each of your plugin projects, but specifying them in a parent project makes them accessible to child projects through inheritance.

Now you’re able to specify dependencies on required Liferay artifacts; let’s create a Liferay plugin project using the archetypes provided by Liferay.