Dynamic Extensions for Alfresco

Dynamic Extensions is a part of the Xenit Open Source Tooling around Alfresco. Xenit is company with a deep expertise and a strong team around Alfresco. If you'd like to learn more about our tools, services and products, please visit our website.

Add OSGi based hot-deploy functionality and Spring annotation based configuration to Alfresco.

Introduction

Rapid development of Alfresco repository extensions in Java. Deploy your code in seconds, not minutes. Life is too short for endless server restarts.

Dynamic Extensions adds an OSGi container to the Alfresco repository, enabling live deployment of Java code, with no need to restart the server. Alfresco itself is not "OSGi-fied" in any way; the OSGi container runs on top of the core Alfresco platform.

Standard Alfresco Platform Extensions use Spring XML based configuration. With Dynamic Extensions, developers have the ability to create Alfresco Platform Extensions using Spring's annotations based configuration.

Installing Dynamic Extensions in Alfresco

Dynamic Extensions (DE) is distributed as an Alfresco Module Package (AMP) extension that can be installed in Alfresco.

Installing the Dynamic Extensions AMP

To support multiple Alfresco versions, different AMPs for each minor Alfresco version update are build and distributed.
E.g. if you are working with Alfresco 6.0.7-ga, you should use the alfresco-dynamic-extensions-repo-60 artifact.

Maven Central Coordinates

All required artifacts, including the AMP to be installed in Alfresco, are available in Maven Central.

<dependency>
    <groupId>eu.xenit</groupId>
    <artifactId>alfresco-dynamic-extensions-repo-${alfresco-version}</artifactId>
    <version>${latest-dynamic-extensions-version}</version>
    <type>amp</type>
</dependency>

alfrescoAmp "eu.xenit:alfresco-dynamic-extensions-repo-${alfrescoVersion}:${dynamicExtensionsVersion}@amp"

These artifacts can be used to automatically install Dynamic Extensions in Alfresco using e.g. the Alfresco Maven SDK or the Alfresco Docker Gradle Plugins

Manual download and install

• Download the latest Dynamic Extensions AMP.
• Use the Module Management Tool to install the AMP in the Alfresco repository of your choosing.
• After restarting Alfresco, open the Control Panel: http://localhost:8080/alfresco/service/dynamic-extensions/.
• Accessing the Control Panel requires an admin account.

Supported Alfresco versions

Dynamic Extensions is systematically integration-tested against:

• Alfresco Enterprise & Community 7.4
• Alfresco Enterprise & Community 7.3
• Alfresco Enterprise & Community 7.2
• Alfresco Enterprise & Community 7.1
• Alfresco Enterprise & Community 7.0
• Alfresco Enterprise & Community 6.2 (Requires hotfix, see below)
• Alfresco Enterprise & Community 6.1 (Requires hotfix, see below)

Integration tests are currently only executed on our private Jenkins build server.

Known Alfresco issues that impact Dynamic Extensions

Alfresco 6.1 / 6.2 - wrong version of 'Commons annotations' used

When using DE on Alfresco 6.1 or 6.2, it is possible that it fails to startup due to following error:

Caused by: java.lang.NoSuchMethodError: javax.annotation.Resource.lookup()Ljava/lang/String;
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.<init>(CommonAnnotationBeanPostProcessor.java:621)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.lambda$buildResourceMetadata$0(CommonAnnotationBeanPostProcessor.java:383)
at org.springframework.util.ReflectionUtils.doWithLocalFields(ReflectionUtils.java:719)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.buildResourceMetadata(CommonAnnotationBeanPostProcessor.java:365)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.findResourceMetadata(CommonAnnotationBeanPostProcessor.java:350)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessMergedBeanDefinition(CommonAnnotationBeanPostProcessor.java:298)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyMergedBeanDefinitionPostProcessors(AbstractAutowireCapableBeanFactory.java:1044)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:550)

The root cause is for this problem is that Alfresco has multiple implementations of the JSR 250 specification, 'Common Annotations' in the WEB-INF/lib/ folder:

1. javax.annotation:javax.annotation-api
2. javax.annotation:jsr250-api
3. org.apache.geronimo.specs:geronimo-annotation_1.0_spec

Only the first one is up to date and contains the correct implementation of the Resource class. The other two versions contain an old implementation of the Resource class, causing the provided error to be thrown by Spring internally.

This is only an issue as of Java 11 (Alfresco 6.1) because earlier versions had an correct implementation of the Resource class embedded in the distribution, and the bootstrap classloader has the highest priority.

This issue has been reported to Alfresco: MNT-20557. Waiting for Alfresco to fix the issue, following workarounds can be used to make DE work on Alfresco 6.1 and 6.2:

• Remove the jsr250-api and geronimo-annotation_1.0_spec jars from the WEB-INF/lib folder of the Alfresco webapp.
• Install this hotfix AMP in your Alfresco distribution, which will overwrite the jsr250-api and geronimo-annotation_1.0_spec jars with empty jars.

Example Dynamic Extensions based Alfresco Platform extension

This example Web Script examines a node and passes information to a Freemarker template:

@Component
@WebScript
public ExampleWebScript {

  @Autowired
  private NodeService nodeService;

  @Uri("/show-node")
  // Example: http://localhost/alfresco/service/show-node?nodeRef=workspace://SpacesStore/12345
  public Map<String, Object> displayNodeName(@RequestParam NodeRef nodeRef) {
    Map<String, Object> model = new HashMap<String, Object>();
    model.put("properties", nodeService.getProperties(nodeRef));    
    return model; // Model is passed to Freemarker template.
  }
}

Note that this is an annotation Web Script. These types of Web Script are configured through Java annotations instead of *.desc.xml descriptors. Annotation Web Scripts are similar to Spring MVC's annotation-based controllers.

Here's the accompanying Freemarker template fragment:

<table>
  <#list properties?keys as name>    
    <tr>
      <th>${name}</th>
      <td>${properties[name]!''}</td>
    </tr>
  </#list>
</table>

This is all the code that is required; there's no need for Spring XML config or Web Script XML descriptors. Hot-reloading and reducing configuration overhead are not particularly novel concepts in the Java development world at large. Essentially, Dynamic Extensions modernizes the development of Alfresco repository extensions.

The example above may be trivial, but the point is that, behind the scenes, services are still wired together through Spring and handled by the Web Script framework. Conceptually there is no real difference between a Dynamic Extension and a regular Alfresco extension. There's just less overhead and more convenience.

Documentation

Please checkout the documentation for further instructions.

License

This project is licensed under the Apache V2 License - see the LICENSE file for details.

Useful links

• Youtube - One hour presentation on using and exploring Dynamic Extensions for Alfresco
• Dynamic Extensions custom Bundle example project