Creating Plugins to Extend Plugins

For Liferay plugins, you can create a new plugin that extends an existing one. By extending a plugin, you can use all its features in your new plugin while keeping your changes/extensions separate from the existing plugin’s source code.

To create a plugin that extends another, follow these steps:

1. Create a new empty plugin in the Plugins SDK. Visit the Developing with the Plugins SDK tutorials for information on how to develop plugins using the Plugins SDK.

2. Remove all the auto-generated files except build.xml and the docroot folder, which should be empty.

3. Copy the original WAR file of the plugin you’d like to extend (e.g., social-networking-portlet-6.2.0.1.war) to the root folder of your new plugin.

4. Add the following line to your build.xml inside the <project> tag to reference the original WAR file you are going to extend:

    <property
        name="original.war.file"
        value="social-networking-portlet-6.2.0.1.war"
    />
   

5. Copy any files from the original plugin that you’re overwriting to your new plugin (using the same folder structure) and run the Ant target merge. Please note that the merge target is called whenever the plugin is compiled. All you have to do is check the Ant output:

    user@host:~/sdk/portlets/my-social-networking-portlet$ ant war
    Buildfile:
    /home/user/sdk/portlets/my-social-networking-portlet/build.xml
   
    compile:
   
    merge:
    [mkdir] Created dir:
    /home/user/sdk/portlets/my-social-networking-portlet/tmp
    [mkdir] Created dir:
    /home/user/sdk/portlets/my-social-networking-portlet/tmp/WEB-INF/
    classes 
    [mkdir] Created dir:
    /home/user/sdk/portlets/my-social-networking-portlet/tmp/WEB-INF/
    lib 
   
    merge-unzip:
    [unzip] Expanding:
    /home/user/sdk/portlets/my-social-networking-portlet/social-
    networking-portlet-6.2.0.1.war into /home/dsanz/sdk/
    portlets/my-social-networking-portlet/tmp 
    [copy] Copying 2 files to
    /home/user/sdk/portlets/my-social-networking-portlet/tmp 
    [mkdir] Created dir:
    /home/user/sdk/portlets/my-social-networking-portlet/docroot/
    WEB-INF/classes
   
    ...
   

6. If the plugin that you’re extending contains a service, you need to overwrite the ClpSerializer.java file. The Service Builder-generated ClpSerializer.java file contains a hard-coded project for _servletContextName. You need to change this to the name of your plugin.

This generates a plugin (you can find the WAR file in the /dist folder of your plugins SDK) which combines the original one with your changes.

Related Topics

Customizing JSPs by Extending the Original

Overriding and Adding Struts Actions

What is Service Builder?