Anatomy of an Ext Plugin

There are two ways you can structure your Ext plugin. The war-core-ext project template/archetype creates the default layout:

• [project name]-ext/
  • src/
    • extImpl/
      • resources/
    • extKernel/
      • resources/
    • extUtilBridges/
      • resources/
    • extUtilJava/
      • resources/
    • extUtilTaglib/
      • resources/
    • main/
      • webapp/
        • WEB-INF/
          • ext-web/
            • docroot/

You can also follow the legacy layout that was used for Ext plugins created with the Plugins SDK in past versions:

• [project name]-ext/
  • docroot/
    • WEB-INF/
      • ext-impl/
        • src/
      • ext-kernel/
        • src/
      • ext-util-bridges/
        • src/
      • ext-util-java/
        • src/
      • ext-util-taglib/
        • src/
      • ext-web/
        • docroot/
          • WEB-INF/

Although the folder names are slightly different, they work the same. This article will refer to the default structure and naming. Here are detailed explanations of the subfolders:

• extImpl: Contains the custom implementation classes and classes that override core classes from portal-impl.jar.

• extKernel: Contains classes that should be available to other plugins. In advanced scenarios, this folder can be used to hold classes that overwrite classes from portal-kernel.jar.

• extUtilBridges, extUtilJava and extUtilTaglib: These folders are needed only in scenarios where you must customize these Liferay libraries: util-bridges.jar, util-java.jar and util-taglib.jar, respectively. If you’re not customizing any of these libraries, you can ignore these folders.

• main/webapp/WEB-INF/ext-web/docroot: Contains the web application’s configuration files, including WEB-INF/struts-config-ext.xml, which lets you customize Liferay’s core struts classes. Note that for Liferay DXP 7.1, there are very few entities left to override in the struts-config.xml file. Any JSPs that you’re customizing also belong here.

By default, several files are also added to the plugin. Here are the most significant files:

• build.gradle/pom.xml: The build file for the Ext plugin project.

• src/main/webapp/WEB-INF/liferay-plugin-package.properties: Contains plugin-specific properties, including the plugin’s display name, version, author, and license type.

• src/main/webapp/WEB-INF/ext-web/docroot/WEB-INF files:

  • liferay-portlet-ext.xml: This file is similar to portlet-ext.xml, but is for additional definition elements specific to Liferay. The liferay-portlet.xml file contains very few definition elements in Liferay DXP 7.1 because portlets were modularized and moved out of core. To override the remaining definition elements, copy the complete definition of the desired portlet from liferay-portlet.xml in Liferay’s source code, then apply the necessary changes.

  • portlet-ext.xml: Used to overwrite the definition of a build-in portlet. The portlet.xml file contains very few portlet configurations in Liferay DXP 7.1 because portlets were modularized and moved out of core. To override this file, copy the complete definition of the desired portlet from portlet-custom.xml in Liferay’s source code, then apply the necessary changes.

  • struts-config-ext.xml and tiles-defs-ext.xml: These files are used to customize the struts actions used by core portlets. Since most portlets were modularized and moved out of core in Liferay DXP 7.1, the struts-config.xml and tiles-defs.xml files are sparsely used.

  • web.xml: Used to overwrite web application configurations and servlet information for Liferay DXP 7.1.

Note: After creating an Ext plugin, remove the files from docroot/WEB-INF/ext-web/docroot/WEB-INF that you don’t need to customize. Removing files you’re not customizing prevents incompatibilities that could manifest from Liferay DXP updates.

Great! Now you’re familiar with an Ext plugin’s folder structure and its most significant files.