Using Liferay IDE with Maven

Wouldn’t it be nice if you could manage your Liferay Maven projects from Liferay IDE? You can! Liferay IDE 2.0 introduces the Maven project configurator (m2e-liferay), or the added support of configuring Maven projects as full Liferay IDE projects. Let’s explore what the Maven project configurator does, how to install it, and how to install its dependencies.

Installing Maven Plugins for Liferay IDE

In order to properly support Maven projects in the IDE, you first need a mechanism to recognize Maven projects as Liferay IDE projects. IDE projects are recognized in Eclipse as faceted web projects that include the appropriate Liferay plugin facet. Therefore, all IDE projects are also Eclipse web projects (faceted projects with web facet installed). In order for the IDE to recognize the Maven project and for it to be able to leverage Java EE tooling features (e.g., the Servers view) with the project, the project must be a flexible web project. Liferay IDE requires that the following Eclipse plugins be installed in order for Maven projects to meet these requirements:

• m2e-core (Maven integration for Eclipse)
• m2e-wtp (Maven integration for WTP)

When you install the m2e-liferay plugin, these dependencies are installed by default. We’ll flesh out the installation process soon, but first, let’s get a deeper understanding of how these plugins work to give us our IDE/Maven compatibility.

The m2e-core plugin is the standard Maven tooling support for Eclipse. It provides dependency resolution classpath management and an abstract project configuration framework for adapters. Also, in order for a Liferay Maven project to be recognized as a flexible web project, the Maven project must be mapped to a flexible web project counterpart. The m2e-wtp plugin. provides project configuration mapping between the Maven models described in the Maven project’s POMs and the corresponding flexible web project supported in Eclipse. With these integration features in place, the only remaining requirement is making sure that the m2e-core plugin can recognize the extra lifecycle metadata mappings necessary for supporting Liferay’s custom goals. Let’s break down the lifecycle mappings just a bit to get a better understanding of what this means.

Both Maven and Eclipse have their own standard build project lifecycles that are independent from each other. Therefore, for both to work together and run seamlessly within Liferay IDE, you need a lifecycle mapping to link both lifecycles into one combined lifecycle. Normally, this would have to be done manually by the user. However, with the m2e-liferay plugin, the lifecycle metadata mapping and Eclipse build lifecycles are automatically combined providing a seamless user experience. The lifecycle mappings for your project can be viewed by right-clicking your project and selecting Properties → Maven → Lifecycle Mapping.

Figure 9.6: View your project's lifecycle mappings to verify successful plugin execution.

When first installing Liferay IDE, the installation startup screen lets you select whether you’d like to install the Maven plugins automatically. Did you miss this during setup? No problem! To install the required Maven plugins, navigate to Help → Install New Software. In the Work with field, insert the following: Liferay IDE repository - http://releases.liferay.com/tools/ide/latest/milestone/.

If the m2e-liferay plugin does not appear, this means you already have it installed. To verify, uncheck the Hide items that are already installed checkbox and look for m2e-liferay in the list of installed plugins. Also, if you’d like to view everything that is bundled with the m2e-liferay plugin, uncheck the Group items by category checkbox.

Figure 9.7: You can install the `m2e-liferay` plugin by searching for software on Liferay IDE's repository.

Awesome! The required Maven plugins are installed and your IDE instance is ready to be mavenized! Next, let’s learn how to configure an existing Maven project.

Configuring your Liferay Maven Project

Now your Liferay IDE instance is Maven-ready and you have an existing Maven project. Let’s investigate what is going on under the hood and configure your project. Note, if you’d like to learn how to create a new Maven project in the IDE, visit the Creating Liferay Plugins with Maven section. Furthermore, you can import an existing Maven project by navigating to File → Import → Maven and selecting the location of your Maven project source code.

Note: Due to the lifecycle mapping of Eclipse and Maven, it is unsafe to manually insert or overwrite the .classpath and .project files and .settings folder. IDE automatically generates these files when a project is imported and updates them appropriately.

The m2e-core plugin delegates your Liferay Maven plugin’s project configuration to the m2e-liferay project configurator. The m2e-wtp project configurator then converts your Liferay WAR package into an Eclipse flexible web project. Next, the m2e-liferay configurator looks for the Liferay Maven plugin to be registered on the POM effective model for WAR type packages. If no Liferay Maven plugin is configured on the effective POM for the project, project configuration ceases. If the plugin is configured, the project configurator validates your project’s configuration, checking it’s POM, parent POM, and the project’s properties. The configurator detects invalid properties and reports them as errors in the IDE’s POM editor. There are a list of key properties that your project must specify in order for it to become a valid Liferay IDE project. The next section titled Using a Parent Plugin Project identifies these properties and explains how they are used.

There are various ways to satisfy these properties–the Maven profile in the Global settings.xml file (recommended), in the User settings.xml file, in the parent pom.xml, or in the project pom.xml directly. You can think of these choices as a hierarchy for how your Maven plugins receive their properties. The project pom.xml overrides the parent pom.xml, the parent pom.xml overrides the User settings.xml file, and the User settings.xml file overrides the Global settings.xml file.

Global settings.xml: provides configuration for all plugins belonging to all users on a machine. This file resides in the ${MAVEN_HOME}/conf/settings.xml directory.

User settings.xml: provides configuration for all plugins belonging to a single user on a machine. This file resides in the ${USER_HOME}/.m2/settings.xml directory.

Parent pom.xml: provides configuration for all modules in the parent project.

Project pom.xml: provides configuration for the single plugin project.

Note that if a profile is active from your settings.xml, its values will override your properties in a POM. If you’d like to specify the properties in a POM, see the next section Using a Parent Plugin Project for more details.

Here’s an example of what a Maven profile looks like inside the settings.xml file.

<profiles>
    <profile>
        <id>sample</id>
            <properties>
                <plugin.type>portlet</plugin.type>
                <liferay.version>6.2.0</liferay.version>
                <liferay.maven.plugin.version>6.2.0</liferay.maven.plugin.version>
                <liferay.auto.deploy.dir>E:\liferay-portal-tomcat-6.2.0-ce-ga1\deploy</liferay.auto.deploy.dir>
                <liferay.app.server.deploy.dir>E:\liferay-portal-tomcat-6.2.0-ce-ga1\tomcat-7.0.42\webapps</liferay.app.server.deploy.dir>
                <liferay.app.server.lib.global.dir>E:\liferay-portal-tomcat-6.2.0-ce-ga1\tomcat-7.0.42\lib\ext</liferay.app.server.lib.global.dir>
                <liferay.app.server.portal.dir>E:\liferay-portal-tomcat-6.2.0-ce-ga1\tomcat-7.0.42\webapps\ROOT</liferay.app.server.portal.dir>
            </properties>
    </profile>
</profiles>

Once you have a Maven profile configured in the ${USER_HOME}/.m2/settings.xml file, you can activate the profile by right-clicking on your project → Properties → Maven and entering the profile IDs that supply the necessary settings into the Active Maven Profiles text field. For example, to reference the profile and properties we listed above, you’d enter sample for the Active Maven Profile. Once you’ve specified all the values, the configurator (m2e-liferay) validates the properties. If there are errors in the pom.xml file, the configurator marks them in Liferay IDE’s POM editor. If you fix a project error, update the project to persist the fix by right-clicking the project → Maven → Update Project.

After your POM configuration meets the requirements, the configurator installs the Liferay plugin facet and your Maven project is officially a Liferay IDE project!

Once you have your Maven project configured, you may want to execute a specific Maven goal such as liferay:build-lang or liferay:build-db that is associated with your build phase. To access your project’s Maven goals and execute them, right-click your project → Liferay → Maven and select the goal to execute. To learn more about Maven’s build lifecycle and plugin goals, visit Apache’s Build Lifecycle Basics guide.

When working with your pom.xml file in the IDE, you’ll notice several different viewing modes to work with:

pom.xml: provides an editable POM as it appears on the file system.

Effective POM: provides a read-only version of your project POM merged with its parent POM(s), settings.xml, and the settings in Eclipse for Maven.

Overview: provides a graphical interface where you can add to and edit the pom.xml file.

Dependencies: provides a graphical interface for adding and editing dependencies in your project, as well as modifying the dependencyManagement section of the pom.xml file.

Dependency Hierarchy: provides hierarchical view of project dependencies and interactive list of resolved dependencies.

Figure 9.8: Liferay IDE provides five interactive modes to help you edit and organize your POM.

By taking advantage of these interactive modes, modifying and organizing your POM and its dependencies has never been easier!

Next, we’ll consider the benefits of using a Maven parent project with your plugin projects.