Starting Module Development

Developing modules for Liferay DXP requires:

• Creating a folder structure: A good folder structure facilitates evolving and maintaining code, especially in collaboration. Popular tools use pre-defined folder structures you’re familiar with.

• Writing code and configuration files: A manifest, Java classes, and resources. Modules stubbed out with them let you focus on implementing logic.

• Compilation: Configuring dependencies and building the module. Common build tools that manage dependencies include Gradle, Maven, and Ant/Ivy.

• Deployment: Interacting with the runtime environment to install, monitor, and modify modules.

There are several good build tools for developing modules. This tutorial demonstrates starting a new module using Liferay Workspace. It’s Liferay’s opinionated build environment based on Gradle and bnd that simplifies module development and automates much of it.

Note: Liferay lets you develop using your favorite tools. In addition to providing Liferay Workspace for those who don’t already have a preferred build environment, Liferay provides good support for Maven and Gradle. The following tutorials and samples demonstrate developing in these environments.

• Maven in Liferay Dev Studio DXP, Maven tutorials, and samples

• Gradle in Liferay Dev Studio DXP and samples

Note: Themes and Layout Templates are not built as modules. The Themes and Layout Templates tutorials demonstrate creating them.

Here are the steps for starting module development:

1. Set up a Liferay Workspace

2. Create a module

3. Build and deploy the module

On completing this tutorial you’ll have created a module and deployed it to a local Liferay DXP bundle.

Setting up a Liferay Workspace

Creating and configuring a Liferay Workspace (Workspace) is straightforward using a tool called Blade CLI (Blade). Blade is a command line tool that creates Workspaces and projects and performs common tasks.

Install Blade if you don’t already have it.

The blade executable is now in the system path.

You can create a Workspace in the current directory by executing this command:

blade init [workspaceName]

You’ve created a Workspace! Its folder structure looks like the one shown in the figure below.

Figure 1: Liferay Workspace aggregates projects so they can leverage the Gradle build environment.

Workspace can be configured to use a Liferay DXP installation bundle anywhere on the local file system. The liferay.workspace.home.dir property in gradle.properties sets the default bundle location to a folder [workspace]/bundles (not yet created). For convenience it’s suggested to install a bundle there. If you install it to a different location, uncomment the liferay.workspace.home.dir property and set it to that location.

Note: User interfaces in Liferay Dev Studio DXP let you create and import Liferay Workspace projects.

To create a project, follow the tutorial Creating a Liferay Workspace Project with Liferay Dev Studio DXP.

To import a project, use the wizard from File → Import → Liferay → Liferay Workspace Project.

The Workspace is ready for creating modules.

Creating a Module

Blade provides project templates and sample projects. The templates stub out files for different types of modules. The samples can be generated in a Workspace and demonstrate many module types. Templates and samples help you create modules fast.

Using Module Templates

The Blade command blade create -l lists the project templates.

Figure 2: Blade's `create` command generates a project based on a template. Executing `create -l` lists the template names.

Note: Liferay Dev Studio DXP’s module wizard lets you select a module project template.

Here’s the command syntax for creating a module:

blade create [options] moduleName

Module templates and their options are described here.

Here’s an example of creating a Liferay MVC Portlet module:

blade create -t mvc-portlet -p com.liferay.docs.mymodule -c MyMvcPortlet my-module

Module projects are created in the modules folder by default.

Here’s the module project anatomy:

• src/main/java/ → Java package root

• src/main/resources/content/ (optional) → Language properties root

• src/main/resources/META-INF/resources/ (optional) → Root for UI templates, such as JSPs

• bnd.bnd → Specifies essential OSGi module manifest headers

• build.gradle → Configures dependencies and more using Gradle

The figure below shows an MVC portlet project.

Figure 3: Liferay modules use the standard Maven folder structure.

Sample modules are another helpful development resource.

Using Sample Modules

An alternative to creating a module from a template is to generate a sample module. Examine them or modify them for your purposes.

This command lists the sample names:

blade samples

The figure below shows the listing.

Figure 4: The `blade samples` command lists the sample modules you can create, examine, and modify to meet your needs.

Here’s the Blade samples command syntax:

blade samples [sampleName]

It creates the sample project in a subfolder.

Building a module and deploying it to Liferay is easy.

Building and Deploying a Module

Liferay Workspace provides Gradle tasks for building and deploying modules. Blade’s blade gw command lets you invoke the Gradle wrapper from any project folder. You can use blade gw just as you would invoke gradlew, without having to specify the wrapper path.

Note: For an even simpler Gradle wrapper command, install gw.

(sudo) jpm install gw@1.0.1

Usage: gw <task>

In a module folder, execute this command to list the Gradle tasks available:

blade gw tasks

Workspace uses bnd to generate the module’s OSGi MANIFEST.MF file and package it in the module JAR. To compile the module and generate the module JAR, execute the jar Gradle task:

blade gw jar

The generated JAR is in the module project’s build/libs folder and ready for deployment.

Start your Liferay DXP server, if you haven’t already started it.

Tip: To open a new terminal window and the Workspace’s Liferay DXP server (bundled with Tomcat or JBoss/Wildfly), execute this command:

blade server start -b

Blade deploys modules to the local Liferay server. It communicates with the OSGi framework using Felix Gogo shell and deploys modules directly to the OSGi container using Felix File Install commands. The command above uses the default port 11311.

To deploy the module, execute this command:

blade deploy

It deploys modules in the current folder tree. For example, executing blade deploy in the [workspace]/modules folder deploys all the modules in that folder and its subfolders.

Liferay Dev Studio DXP lets you deploy modules by dragging them from the Package Explorer onto the Liferay server. Dev Studio DXP provides access to Liferay Workspace Gradle tasks too.

Figure 5: Liferay Dev Studio DXP lets you deploy modules using drag-and-drop.

Note: Blade CLI directly installs modules into the OSGi container. Blade stores the module differently in Liferay than if you were to copy the module into the LIFERAY_HOME/deploy folder.

Once you’ve deployed a portlet module, it’s available in the Liferay UI under the application category and name you specified via the portlet component’s com.liferay.portlet.display-category and javax.portlet.display-name properties.

Figure 6: Here's a bare-bones portlet based on a project template.

Redeploying Module Changes Automatically

Blade lets you set a watch on changes to a module project’s output files. If they’re modified, Blade redeploys the module automatically. To set a watch on a module at deployment, execute this command in the module project:

blade deploy -w

Here’s output from deploying (and watching) a module named com.liferay.docs.mymodule:

E:\workspaces\my-liferay-workspace\modules\my-module-project>blade deploy -w

:modules:my-module-project:compileJava UP-TO-DATE
:modules:my-module-project:buildCSS UP-TO-DATE
:modules:my-module-project:processResources UP-TO-DATE
:modules:my-module-project:transpileJS SKIPPED
:modules:my-module-project:configJSModules SKIPPED
:modules:my-module-project:classes UP-TO-DATE
:modules:my-module-project:jar UP-TO-DATE
:modules:my-module-project:assemble UP-TO-DATE
:modules:my-module-project:build

BUILD SUCCESSFUL

Total time: 2.962 secs
install file:/E:/workspaces/my-liferay-workspace/modules/my-module-project/build/libs/com.liferay.docs.mymodule-1.0.0.jar
Bundle ID: 505
start 505

Scanning E:\workspaces\my-liferay-workspace\modules\my-module-project

...

Waiting for changes to input files of tasks... (ctrl-d then enter to exit)

The command output indicates that the module is installed and started, reports the module’s OSGi bundle ID, and stands ready to deploy changes to the module.

Congratulations on a great start to developing your module!

Related Articles

Configuring Dependencies

Liferay Workspace

Tooling

OSGi Basics for Liferay Development

Portlets