Using Liferay Maven Parent Plugin Projects

Maven supports project inheritance. You can create a parent project that contains properties that child projects inherit. This saves time, since you don’t need to specify those properties in each project. It also makes your projects easier to maintain since if you have to change the value of a property belonging to each of your projects, you only need to change it in the parent 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.

This tutorial demonstrates Maven inheritance with a Liferay Maven project that includes a parent/child relationship. Whether or not you’re 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.

If you’ll be creating multiple Liferay plugins, you should create a parent project and then specify the general settings needed to build your plugins for Liferay. The parent project functions similarly to the project root of the Liferay Plugins SDK. Its pom.xml file specifies information to be used by any child plugin projects that refer to it. Of course, you can always specify information in each individual plugin’s POM, but it’s more convenient to use the parent project’s POM for sharing common information.

Follow these steps to create a Liferay Maven parent plugin project:

1. Create a directory for your parent plugin project.

2. In your new parent plugin project directory, create a POM file named pom.xml.

   For example, here’s POM XML code for a parent plugin project named sample-parent-project:

   <?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.app.server.deploy.dir>
   			${liferay.app.server.deploy.dir}
   		</liferay.app.server.deploy.dir>
   
   		<liferay.app.server.lib.global.dir>
   			${liferay.app.server.lib.global.dir}
   		</liferay.app.server.lib.global.dir>
   
   		<liferay.app.server.portal.dir>
   			${liferay.app.server.portal.dir}
   		</liferay.app.server.portal.dir>
   
   		<liferay.auto.deploy.dir>
   			${liferay.auto.deploy.dir}
   		</liferay.auto.deploy.dir>
   
   		<liferay.version>
   			${liferay.version}
   		</liferay.version>
   
   		<liferay.maven.plugin.version>
   			${liferay.maven.plugin.version}
   		</liferay.maven.plugin.version>
   	</properties>
   
   	<dependencies>
   		<dependency>
   			<groupId>com.liferay.portal</groupId>
   			<artifactId>portal-client</artifactId>
   			<version>6.2.0-GA1</version>
   		</dependency>
   		<dependency>
   			<groupId>com.liferay.portal</groupId>
   			<artifactId>portal-impl</artifactId>
   			<version>6.2.0-GA1</version>
   			<scope>provided</scope>
   		</dependency>
   		<dependency>
   			<groupId>com.liferay.portal</groupId>
   			<artifactId>portal-pacl</artifactId>
   			<version>6.2.0-GA1</version>
   			<scope>provided</scope>
   		</dependency>
   		<dependency>
   			<groupId>com.liferay.portal</groupId>
   			<artifactId>portal-service</artifactId>
   			<version>6.2.0-GA1</version>
   			<scope>provided</scope>
   		</dependency>
   		<dependency>
   			<groupId>com.liferay.portal</groupId>
   			<artifactId>portal-web</artifactId>
   			<version>6.2.0-GA1</version>
   			<type>war</type>
   			<scope>provided</scope>
   		</dependency>
   		<dependency>
   			<groupId>com.liferay.portal</groupId>
   			<artifactId>util-bridges</artifactId>
   			<version>6.2.0-GA1</version>
   		</dependency>
   		<dependency>
   			<groupId>com.liferay.portal</groupId>
   			<artifactId>util-java</artifactId>
   			<version>6.2.0-GA1</version>
   		</dependency>
   		<dependency>
   			<groupId>com.liferay.portal</groupId>
   			<artifactId>util-slf4j</artifactId>
   			<version>6.2.0-GA1</version>
   		</dependency>
   		<dependency>
   			<groupId>com.liferay.portal</groupId>
   			<artifactId>util-taglib</artifactId>
   			<version>6.2.0-GA1</version>
   		</dependency>
   	</dependencies>
   
   </project>
   

   The POM starts by specifying the model version that Maven supports, your project’s Maven coordinates, your project’s name, and your company’s URL.

   Next, the POM specifies some key Liferay property elements that your plugins require in order to be deployed to your Liferay portal. You can conveniently specify these values in a parent project for all of your child plugin projects to leverage. A plugin project can override any of its parent’s properties by specifying the desired property explicitly in the child plugin project’s POM.

   If you use contents from the above example POM, make sure to replace each Liferay property value (e.g., replace ${liferay.app.server.deploy.dir} and other dereferenced liferay.* properties) with the appropriate value based on your Liferay environment.

   Each key Liferay property is described below:

   • liferay.app.server.deploy.dir: Your app server’s deployment directory.
   • liferay.app.server.lib.global.dir: Your app server’s global library directory.
   • liferay.app.server.portal.dir: The path to Liferay’s deployment directory on the app server.
   • liferay.auto.deploy.dir: The path of your Liferay bundle’s hot-deploy directory deploy. By specifying your Liferay instance’s deploy directory in the POM, you’re telling Maven exactly where to deploy your plugin artifacts.
   • liferay.maven.plugin.version: The version of the Liferay Maven Plugin you are using.
   • liferay.version: The version of Liferay you are using.

   Here’s an example of specifying these properties for Liferay bundled with Apache Tomcat in a directory C:\liferay-portal-6.2:

   <properties>
   	<liferay.app.server.deploy.dir>
   		C:\liferay-portal-6.2\tomcat-7.0.42\webapps
   	</liferay.app.server.deploy.dir>
   
   	<liferay.app.server.lib.global.dir>
   		C:\liferay-portal-6.2\tomcat-7.0.42\lib\ext
   	</liferay.app.server.lib.global.dir>
   
   	<liferay.app.server.portal.dir>
   		C:\liferay-portal-6.2\tomcat-7.0.42\webapps\root
   	</liferay.app.server.portal.dir>
   
   	<liferay.auto.deploy.dir>
   		C:\liferay-portal-6.2\deploy
   	</liferay.auto.deploy.dir>
   
   	<liferay.maven.plugin.version>
   		6.2.0
   	</liferay.maven.plugin.version>
   
   	<liferay.version>
   		6.2.0
   	</liferay.version>
   </properties>
   

   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 of the Using Maven From Liferay IDE tutorial.

   The Liferay plugins that you develop depend on several Liferay artifacts. You can include them in individual dependency elements within the POM’s dependencies element. All of 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.

You’ve configured your parent plugin project.

Related Topics:

Developing Plugins with Liferay IDE Developing with Maven