Using the WAB Generator

You can create applications for Liferay DXP as Java EE-style Web Application ARchive (WAR) artifacts or as Java ARchive (JAR) OSGi bundle artifacts. Some portlet types, however, limit your flexibility. Portlets like Spring MVC and JSF must be packaged as WAR artifacts because their frameworks are designed for Java EE. Therefore, they expect a WAR layout and require Java EE resources such as the WEB-INF/web.xml descriptor.

Liferay provides a way for these WAR-styled plugins to be deployed and treated like OSGi modules by Liferay’s OSGi runtime. They can be converted to WABs.

Liferay DXP supports the OSGi Web Application Bundle (WAB) standard for deployment of Java EE style WARs. Simply put, a WAB is an archive that has a WAR layout and contains a META-INF/MANIFEST.MF file with the Bundle-SymbolicName OSGi directive. A WAB is an OSGi bundle. Although the project source has a WAR layout, the artifact filename may end with either the .jar or .war extension.

Liferay only supports the use of WABs that have been auto-generated by the WAB Generator. The WAB Generator transforms a traditional WAR-style plugin into a WAB during deployment. So what exactly does the WAB Generator do to a WAR file to transform it into a WAB?

The WAB Generator detects packages referenced in the plugin WAR’s JSPs, descriptor files, and classes (in WEB-INF/classes and embedded JARs). The descriptor files include web.xml, liferay-web.xml, portlet.xml, liferay-portlet.xml, and liferay-hook.xml. The WAB Generator verifies whether the detected packages are in the plugin’s WEB-INF/classes folder or in an embedded JAR in the WEB-INF/lib folder. Packages that aren’t found in either location are added to an Import-Package header in the WAB’s META-INF/MANIFEST.MF file.

To import a package that is only referenced in the following types of locations, you must add an Import-Package OSGi header to the plugin’s WEB-INF/liferay-plugin-package.properties file and add the package to that header’s list of values.

  • Unrecognized descriptor file
  • Custom or unrecognized descriptor element or attribute
  • Reflection code
  • Classloader code

The WAB folder structure and WAR folder structure differ. Consider the following folder structure of a WAR-style portlet:

  • my-war-portlet
    • src
      • main
        • java
        • webapp
          • WEB-INF
            • classes
            • lib
            • resources
            • views
            • faces-config.xml
            • liferay-display.xml
            • liferay-plugin-package.properties
            • liferay-portlet.xml
            • portlet.xml
            • web.xml

When a WAR-style portlet is deployed to Liferay and processed by the WAB Generator, the portlet’s folder structure is transformed to something like this

  • my-war-portlet-that-is-now-a-wab
    • META-INF
      • MANIFEST.MF
    • WEB-INF
      • classes
      • lib
      • resources
      • views
      • faces-config.xml
      • liferay-display.xml
      • liferay-plugin-package.properties
      • liferay-portlet.xml
      • portlet.xml
      • web.xml

The major difference is the addition of the META-INF/MANIFEST.MF file. The WAB Generator automatically generates an OSGi-ready MANIFEST.MF file. If you want to affect the content of the manifest file, you can place bnd directives and OSGi headers directly into your plugin’s liferay-plugin-package.properties file. It’s pointless to add a bnd.bnd file or a build-time plugin (e.g., bnd-maven-plugin) to your WAR plugin, because the generated WAB cannot use of them.

Do you want to try generating a WAB? Follow the steps below to see the WAB Generator in action.

  1. Create a WAR-style plugin that follows a similar structure to the one outlined above. You can download an example WAR-style portlet here, for demonstration.

  2. Open your Liferay DXP instance in a file explorer and add a portal-ext.properties file with the following properties:

    module.framework.web.generator.generated.wabs.store=true
    module.framework.web.generator.generated.wabs.store.dir=${module.framework.base.dir}/wabs
    

    These properties store your generated WAB into your Liferay instance’s osgi/wabs folder. You can learn more about these properties in the Module Framework Web Application Bundles properties section. Restart Liferay to use these properties.

  3. Copy your WAR plugin in your Liferay instance’s deploy folder.

  4. Navigate to your Liferay instance’s osgi/wabs folder and inspect the generated WAB.

Awesome! You’ve seen the WAB Generator in action!

Configurable Applications

« Waiting on Lifecycle EventsService Trackers »
この記事は役に立ちましたか?
0人中0人がこの記事が役に立ったと言っています