Introduction to Surf Extension Modules

If you look in the tomcat/webapps/share/WEB-INF/classes/SkyVault directory of your SkyVault installation, then you’ll notice a number of files ending with -config.xml, such as for example share-config.xml. These files contain configuration that is loaded into a Spring bean when SkyVault starts and is accessed by Share code to dictate many different aspects of its behaviour.

To customize this configuration you would not normally change these files directly, but instead make your changes in the tomcat/shared/classes/alfresco/web-extension/share-config-custom.xml file, which overrides the default configuration in the exploded Share webapp. Changes to web-extension/share-config-custom.xml can be done at runtime and take effect after a Share Web Script Refresh. However, there is no way from the UI to disable or enable configuration, you need file system access. There is also no easy and straight forward way to split up the configuration in different units, name them, and version them.

Further on, with the web-extension/share-config-custom.xml file it is not possible to work with Surf pages and components. You can for example not add a component to a page, update a component, or hide a component.

This is where Spring Surf Extension Modules comes into the picture, they enable dynamic control of the Share configuration at runtime from the user interface. Extension Modules also give you full control over a Surf Page in that you can add, update, and remove components that it is made up of. These modules can be deployed and un-deployed without restarting the server. Note however that installing a new module requires a server restart.

Extension modules makes it more straight forward to organize, name, version, and manage your configuration. Instead of having everything in one long share-config-custom.xml file, configuration can now be named and kept in different modules so it is easy for an Administrator to deploy and un-deploy different configuration settings at runtime.

Each module is processed for every request that comes into the Share web application to determine what configuration that should be applied. If a module should only be processed for certain requests, then evaluators can be used to determine when a module should be processed. This is an improvement to how the share-config-custom.xml configuration works, which is applied to all requests and you cannot add any evaluators.

Extension modules are defined in XML files that are stored under the tomcat/shared/classes/alfresco/web-extension/site-data/extensions directory.

Now, let's look at how to use an extension module to implement a Share customization. In the following sample customization we want to hide the External User Invite functionality in a site. The following picture illustrates what component we want to hide in the Invite Users page:

To hide this component we need to find out the region-id, source-id, and scope for it so we can use that when defining the extension module. If you are not up to speed on Surf see Spring Surf deep dive. We can get to this information by using a tool called SurfBug (more info on how to enable this tool). When this tool is enabled, and we refresh the page, red lines will show up and mark the different components on the page:

Clicking the component area brings up an information window with all the Surf data that we need:

<extension>
    <modules>
        <module>
            <id>Hide Add External Users</id>
            <auto-deploy>true</auto-deploy>
            <components>
                <component>
                    <region-id>addemail</region-id>
                    <source-id>invite</source-id>
                    <scope>template</scope>
                    <sub-components>
                        <sub-component id="default">
                            <evaluations>
                                <evaluation id="disable-add-external-users">
                                    <render>false</render>
                                </evaluation>
                            </evaluations>
                        </sub-component>
                    </sub-components>
                </component>
            </components>
        </module>
    </modules>
</extension>    

<extension>
    <modules>
        <module>
            <id>Override Document Library</id>
            <auto-deploy>true</auto-deploy>
            <configurations>
                <config evaluator="string-compare" condition="DocumentLibrary">
                    <create-content>
                         <content id="plain-text" mimetype="text/plain" label="Create an Acme Document" itemid="acme:doc"/>
                    </create-content>
                </config>

<extension>
    <modules>
        <module>
            <id>Override Document Library</id>
            <auto-deploy>true</auto-deploy>
            <customizations>
                <customization>
                    <targetPackageRoot>org.alfresco.components.documentlibrary</targetPackageRoot>
                    <sourcePackageRoot>org.alfresco.training.components.documentlibrary.customization</sourcePackageRoot>

<extension>
    <modules>
        <module>
            <id>Override Document Library</id>
            <auto-deploy>true</auto-deploy>
            <customizations>
                <customization>
                    <targetPackageRoot>org.acme</targetPackageRoot>
                    <dependencies>
                        <css>/res/demo/dependencies/styles.css</css>
                        <js>/res/demo/dependencies/script.js</js>
                    </dependencies>

The following table compares share-config-custom.xml with Surf Extension modules: