Article summary

Summary

Discusses how to create a custom AEM event handler that responds to JCR events, such as when a node is created.  

This article uses an Adobe Maven Archetype project to build an OSGi bundle. If you are not familiar with an Adobe Maven Archetype project, it is recommended that you read the following article: Creating your first AEM Service using an Adobe Maven Archetype project.

This article was updated to use this Maven command to build the OSGi bundle:

mvn archetype:generate -DarchetypeRepository=https://repo.adobe.com/nexus/content/groups/public/ -DarchetypeGroupId=com.day.jcr.vault -DarchetypeArtifactId=multimodule-content-package-archetype -DarchetypeVersion=1.0.2 -DgroupId=com.adobe.aem.events -DartifactId=eventhandler -Dversion=1.0-SNAPSHOT -Dpackage=com.adobe.aem.events -DappsFolderName=myproject -DartifactName="My Project" -DcqVersion="5.6.1" -DpackageGroup="My Company"

Digital Marketing Solution(s) Adobe Experience Manager (Adobe CQ)
Audience
Developer (intermediate)
Required Skills
Java, Maven, JCR, Sling
Tested On Adobe Experience Manager 5.5, 5.6

Introduction

You can develop a custom event handler for Adobe Experience Manager (AEM) that responds to events that occur at the JCR level. For example, you can write an event handler to respond to the following JCR events:

  • A node was added
  • A node was moved
  • A node was deleted
  • A property was added to a node
  • A property was changed
  • A property was deleted

To create an AEM event handler, create an OSGi bundle that contains a class that implements javax.jcr.observation.EventListener. For information, see EventListener.

The following illustration shows a client making a change in an AEM web page that results in a new node being created in the AEM JCR. For example, a new customer signs up that results in a new node being created within the AEM JCR. The custom event handler listens for that event and responds.

Events

This development article guides you through creating an AEM event handler that responds to the 'Add Node' event that occurs when a node is added under content/claim. Application logic that represents an Event Hander is implemented as an OSGi bundle that is built using Declarative Services (DS) and Maven. DS is used to inject a ResourceResolverFactory instance into the service. The OSGi bundle is a managed component, which means that the OSGi service container creates the ResourceResolverFactory instance.

Setup Maven in your development environment

You can use Maven to build an OSGi bundle that contains a Sling Servlet. Maven manages required JAR files that a Java project needs in its class path. Instead of searching the Internet trying to find and download third-party JAR files to include in your project’s class path, Maven manages these dependencies for you.

You can download Maven 3 from the following URL:

http://maven.apache.org/download.html

After you download and extract Maven, create an environment variable named M3_HOME. Assign the Maven install location to this environment variable. For example:

C:\Programs\Apache\apache-maven-3.0.4

Set up a system environment variable to reference Maven. To test whether you properly setup Maven, enter the following Maven command into a command prompt:

%M3_HOME%\bin\mvn -version

This command provides Maven and Java install details and resembles the following message:

Java home: C:\Programs\Java64-6\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 7", version: "6.1", arch: "amd64", family: "windows"

Note:

It is recommended that you use Maven 3.0.3 or greater. For more information about setting up Maven and the Home variable, see: Maven in 5 Minutes.

Next, copy the Maven configuration file named settings.xml from [install location]\apache-maven-3.0.4\conf\ to your user profile. For example, C:\Users\scottm\.m2\.

You have to configure your settings.xml file to use Adobe’s public repository. For information, see Adobe Public Maven Repository at http://repo.adobe.com/.

The following XML code represents a settings.xml file that you can use. 

<?xml version="1.0" encoding="UTF-8"?>

<!--
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
-->

<!--
 | This is the configuration file for Maven. It can be specified at two levels:
 |
 |  1. User Level. This settings.xml file provides configuration for a single user, 
 |                 and is normally provided in ${user.home}/.m2/settings.xml.
 |
 |                 NOTE: This location can be overridden with the CLI option:
 |
 |                 -s /path/to/user/settings.xml
 |
 |  2. Global Level. This settings.xml file provides configuration for all Maven
 |                 users on a machine (assuming they're all using the same Maven
 |                 installation). It's normally provided in 
 |                 ${maven.home}/conf/settings.xml.
 |
 |                 NOTE: This location can be overridden with the CLI option:
 |
 |                 -gs /path/to/global/settings.xml
 |
 | The sections in this sample file are intended to give you a running start at
 | getting the most out of your Maven installation. Where appropriate, the default
 | values (values used when the setting is not specified) are provided.
 |
 |-->
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" 
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
          xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">
  <!-- localRepository
   | The path to the local repository maven will use to store artifacts.
   |
   | Default: ~/.m2/repository
  <localRepository>/path/to/local/repo</localRepository>
  -->

  <!-- interactiveMode
   | This will determine whether maven prompts you when it needs input. If set to false,
   | maven will use a sensible default value, perhaps based on some other setting, for
   | the parameter in question.
   |
   | Default: true
  <interactiveMode>true</interactiveMode>
  -->

  <!-- offline
   | Determines whether maven should attempt to connect to the network when executing a build.
   | This will have an effect on artifact downloads, artifact deployment, and others.
   |
   | Default: false
  <offline>false</offline>
  -->

  <!-- pluginGroups
   | This is a list of additional group identifiers that will be searched when resolving plugins by their prefix, i.e.
   | when invoking a command line like "mvn prefix:goal". Maven will automatically add the group identifiers
   | "org.apache.maven.plugins" and "org.codehaus.mojo" if these are not already contained in the list.
   |-->
  <pluginGroups>
    <!-- pluginGroup
     | Specifies a further group identifier to use for plugin lookup.
    <pluginGroup>com.your.plugins</pluginGroup>
    -->
  </pluginGroups>

  <!-- proxies
   | This is a list of proxies which can be used on this machine to connect to the network.
   | Unless otherwise specified (by system property or command-line switch), the first proxy
   | specification in this list marked as active will be used.
   |-->
  <proxies>
    <!-- proxy
     | Specification for one proxy, to be used in connecting to the network.
     |
    <proxy>
      <id>optional</id>
      <active>true</active>
      <protocol>http</protocol>
      <username>proxyuser</username>
      <password>proxypass</password>
      <host>proxy.host.net</host>
      <port>80</port>
      <nonProxyHosts>local.net|some.host.com</nonProxyHosts>
    </proxy>
    -->
  </proxies>

  <!-- servers
   | This is a list of authentication profiles, keyed by the server-id used within the system.
   | Authentication profiles can be used whenever maven must make a connection to a remote server.
   |-->
  <servers>
    <!-- server
     | Specifies the authentication information to use when connecting to a particular server, identified by
     | a unique name within the system (referred to by the 'id' attribute below).
     | 
     | NOTE: You should either specify username/password OR privateKey/passphrase, since these pairings are 
     |       used together.
     |
    <server>
      <id>deploymentRepo</id>
      <username>repouser</username>
      <password>repopwd</password>
    </server>
    -->
    
    <!-- Another sample, using keys to authenticate.
    <server>
      <id>siteServer</id>
      <privateKey>/path/to/private/key</privateKey>
      <passphrase>optional; leave empty if not used.</passphrase>
    </server>
    -->
  </servers>

  <!-- mirrors
   | This is a list of mirrors to be used in downloading artifacts from remote repositories.
   | 
   | It works like this: a POM may declare a repository to use in resolving certain artifacts.
   | However, this repository may have problems with heavy traffic at times, so people have mirrored
   | it to several places.
   |
   | That repository definition will have a unique id, so we can create a mirror reference for that
   | repository, to be used as an alternate download site. The mirror site will be the preferred 
   | server for that repository.
   |-->
  <mirrors>
    <!-- mirror
     | Specifies a repository mirror site to use instead of a given repository. The repository that
     | this mirror serves has an ID that matches the mirrorOf element of this mirror. IDs are used
     | for inheritance and direct lookup purposes, and must be unique across the set of mirrors.
     |
    <mirror>
      <id>mirrorId</id>
      <mirrorOf>repositoryId</mirrorOf>
      <name>Human Readable Name for this Mirror.</name>
      <url>http://my.repository.com/repo/path</url>
    </mirror>
     -->
  </mirrors>
  
  <!-- profiles
   | This is a list of profiles which can be activated in a variety of ways, and which can modify
   | the build process. Profiles provided in the settings.xml are intended to provide local machine-
   | specific paths and repository locations which allow the build to work in the local environment.
   |
   | For example, if you have an integration testing plugin - like cactus - that needs to know where
   | your Tomcat instance is installed, you can provide a variable here such that the variable is 
   | dereferenced during the build process to configure the cactus plugin.
   |
   | As noted above, profiles can be activated in a variety of ways. One way - the activeProfiles
   | section of this document (settings.xml) - will be discussed later. Another way essentially
   | relies on the detection of a system property, either matching a particular value for the property,
   | or merely testing its existence. Profiles can also be activated by JDK version prefix, where a 
   | value of '1.4' might activate a profile when the build is executed on a JDK version of '1.4.2_07'.
   | Finally, the list of active profiles can be specified directly from the command line.
   |
   | NOTE: For profiles defined in the settings.xml, you are restricted to specifying only artifact
   |       repositories, plugin repositories, and free-form properties to be used as configuration
   |       variables for plugins in the POM.
   |
   |-->
  <profiles>
    <!-- profile
     | Specifies a set of introductions to the build process, to be activated using one or more of the
     | mechanisms described above. For inheritance purposes, and to activate profiles via <activatedProfiles/>
     | or the command line, profiles have to have an ID that is unique.
     |
     | An encouraged best practice for profile identification is to use a consistent naming convention
     | for profiles, such as 'env-dev', 'env-test', 'env-production', 'user-jdcasey', 'user-brett', etc.
     | This will make it more intuitive to understand what the set of introduced profiles is attempting
     | to accomplish, particularly when you only have a list of profile id's for debug.
     |
     | This profile example uses the JDK version to trigger activation, and provides a JDK-specific repo.
    <profile>
      <id>jdk-1.4</id>

      <activation>
        <jdk>1.4</jdk>
      </activation>

      <repositories>
        <repository>
          <id>jdk14</id>
          <name>Repository for JDK 1.4 builds</name>
          <url>http://www.myhost.com/maven/jdk14</url>
          <layout>default</layout>
          <snapshotPolicy>always</snapshotPolicy>
        </repository>
      </repositories>
    </profile>
    -->

    <!--
     | Here is another profile, activated by the system property 'target-env' with a value of 'dev',
     | which provides a specific path to the Tomcat instance. To use this, your plugin configuration
     | might hypothetically look like:
     |
     | ...
     | <plugin>
     |   <groupId>org.myco.myplugins</groupId>
     |   <artifactId>myplugin</artifactId>
     |   
     |   <configuration>
     |     <tomcatLocation>${tomcatPath}</tomcatLocation>
     |   </configuration>
     | </plugin>
     | ...
     |
     | NOTE: If you just wanted to inject this configuration whenever someone set 'target-env' to
     |       anything, you could just leave off the <value/> inside the activation-property.
     |
    <profile>
      <id>env-dev</id>

      <activation>
        <property>
          <name>target-env</name>
          <value>dev</value>
        </property>
      </activation>

      <properties>
        <tomcatPath>/path/to/tomcat/instance</tomcatPath>
      </properties>
    </profile>
    -->
  

<profile>

                <id>adobe-public</id>

                <activation>

                    <activeByDefault>true</activeByDefault>

                </activation>

                <repositories>

                  <repository>

                    <id>adobe</id>

                    <name>Nexus Proxy Repository</name>

                    <url>http://repo.adobe.com/nexus/content/groups/public/</url>

                    <layout>default</layout>

                  </repository>

                </repositories>

                <pluginRepositories>

                  <pluginRepository>

                    <id>adobe</id>

                    <name>Nexus Proxy Repository</name>

                    <url>http://repo.adobe.com/nexus/content/groups/public/</url>

                    <layout>default</layout>

                  </pluginRepository>

                </pluginRepositories>

            </profile>

</profiles>

  <!-- activeProfiles
   | List of profiles that are active for all builds.
   |
  <activeProfiles>
    <activeProfile>alwaysActiveProfile</activeProfile>
    <activeProfile>anotherAlwaysActiveProfile</activeProfile>
  </activeProfiles>
  -->
</settings>

Create an Experience Manager archetype project 

You can create an Experience Manager archetype project by using the Maven archetype plugin. In this example, assume that the working directory is C:\AdobeCQ. 

plugin1

To create an Experience Manager archetype project, perform these steps:

1. Open the command prompt and go to your working directory (for example, C:\AdobeCQ).

2. Run the following Maven command:

mvn archetype:generate -DarchetypeRepository=https://repo.adobe.com/nexus/content/groups/public/ -DarchetypeGroupId=com.day.jcr.vault -DarchetypeArtifactId=multimodule-content-package-archetype -DarchetypeVersion=1.0.2 -DgroupId=com.adobe.aem.events -DartifactId=eventhandler -Dversion=1.0-SNAPSHOT -Dpackage=com.adobe.aem.events -DappsFolderName=myproject -DartifactName="My Project" -DcqVersion="5.6.1" -DpackageGroup="My Company"

3. When prompted, specify Y.

4. Once done, you will see a message like:

[INFO] Finished at: Wed Mar 27 13:38:58 EDT 2013
[INFO] Final Memory: 10M/184M

5. Change the command prompt to the generated project. For example: C:\AdobeCQ\eventhandler.

6. Run the following Maven command:

mvn eclipse:eclipse

7. After you run this command, you can import the project into Eclipse as discussed in the next section.

 

Add Java files to the Maven project using Eclipse

To make it easier to work with the Maven generated project, import it into the Eclipse development environment, as shown in the following illustration. 

project

 

Note:

Be sure to work in the eventhandler-bundle project. You can delete the eventhandler-content project. Also delete src/test/java source files. Besure to work in the scr/main/java folder. 

Add event handler application logic to a new class named SimpleDSComponent class. Add this class to the com.adobe.aem.events package. Ensure this class by implements the  javax.jcr.observation.EventListener interface.

public class SimpleDSComponent implements Runnable,EventListener

For more information about an EventListener information, see EventListener.  

Java

You use an ObservationManager instance to define the characteristics of the event handler. For example, you can define the JCR location that the event handler monitors as well as the event type (for example, a node is added to the JCR). As well you can define the type of node that the event handler reacts to (for example, an nt:unstructured). In the following code example, an ObservationManager instance defines the following characteristics:

  • The event handler monitors the following JCR location: content/claims.
  • The event type is a node being added to this JCR location.
  • The type of node is nt:unstructured.

Notice that the ObservationManager object's addEventListener method is invoked.

observationManager = session.getWorkspace().getObservationManager();
final String[] types = { "nt:unstructured","sling:Folder" };
final String path = "/content/claim"; // define the path
observationManager.addEventListener(this, Event.NODE_ADDED, path, true, null, types, false);

When the event occurs, the event handler invokes the onEvent method. This method must be part of the event handler class because the class implements EventListener. In the following example, when the event occurs (a node of type nt:unstructured is added to content/claim), the event handler logs the time in the AEM log file.

//Define app logic that is fired when the event occurs - simply track the time
//when the event occurred.
public void onEvent(EventIterator itr) {

Calendar cal = Calendar.getInstance();
cal.getTime();
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");

//log the time when the event occurred
log.info("A new node was added to content/claim at : " +cal.getTime());
}

The following Java code example represents the SimpleDSComponent that defines an AEM event handler.

package com.adobe.aem.events;

import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Service;

import org.osgi.framework.BundleContext;
import org.osgi.service.component.ComponentContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.Arrays;

import javax.jcr.Node;
import javax.jcr.Repository;
import javax.jcr.RepositoryException;
import javax.jcr.Session;
import javax.jcr.observation.Event;
import javax.jcr.observation.EventIterator;
import javax.jcr.observation.EventListener;
import javax.jcr.observation.ObservationManager;
import org.apache.sling.jcr.api.SlingRepository;
import org.osgi.service.component.ComponentContext;

import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Properties;
import org.apache.felix.scr.annotations.Property;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.Service;

//Sling Imports
import org.apache.sling.api.resource.ResourceResolverFactory ; 
import org.apache.sling.api.resource.ResourceResolver; 
import org.apache.sling.api.resource.Resource; 

import java.text.SimpleDateFormat;
import java.util.Calendar;


import org.apache.sling.jcr.api.SlingRepository;

/**
 * Just a simple DS Component
 */
@Component(immediate=true)
@Service
public class SimpleDSComponent implements EventListener {
    
    private Logger log = LoggerFactory.getLogger(this.getClass());
    
    private BundleContext bundleContext;
    
    
    @Reference
    private SlingRepository repository;
    
  //Inject a Sling ResourceResolverFactory
    @Reference
    private ResourceResolverFactory resolverFactory;
    
    private Session session;
    
    private ObservationManager observationManager;
    
    public void run() {
        log.info("Running...");
    }
    
    
    //Place app logic here to define the AEM Custom Event Handler
    protected void activate(ComponentContext ctx) {
        this.bundleContext = ctx.getBundleContext();
        
        try
        {
        	  	 
        	//Invoke the adaptTo method to create a Session 
            // ResourceResolver resourceResolver = resolverFactory.getAdministrativeResourceResolver(null);
             session = repository.loginAdministrative(null);
        	 
        	// Setup the event handler to respond to a new claim under content/claim.... 
                observationManager = session.getWorkspace().getObservationManager();
                 final String[] types = { "nt:unstructured","sling:Folder" };
                 final String path = "/content/claim"; // define the path
                 observationManager.addEventListener(this, Event.NODE_ADDED, path, true, null, null, false);
                 log.info("Observing property changes to {} nodes under {}", Arrays.asList(types), path);
                          
         }
        catch(Exception e)
        {
        	e.printStackTrace(); 
         }
        }

         protected void deactivate(ComponentContext componentContext) throws RepositoryException {
             
             if(observationManager != null) {
                 observationManager.removeEventListener(this);
             }
             if (session != null) {
                 session.logout();
                 session = null;
               }
         }

        //Define app logic that is fired when the event occurs - simply track the time 
        //when the event occurred. 
     	public void onEvent(EventIterator itr) {
     		
     		//Calendar cal = Calendar.getInstance();
        	//cal.getTime();
        	//SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
        	 
        	//log the time when the event occurred 
     		log.info("A new node was added to content/claim ");
     		    		
     	}
}

Modify the Maven POM file 

Modify the POM files to successfully build the OSGi bundle. In the POM file located at C:\AdobeCQ\eventhandler, add the following dependencies.

  • org.apache.felix.scr
  • org.apache.felix.scr.annotations
  • javax.jcr.observation.EventListener
  • org.apache.sling.api.resource.ResourceResolverFactory

The following XML represents the POM file to build the custom event handler. Copy the XML code to your POM file.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd ">
    <modelVersion>4.0.0</modelVersion>
    <!-- ====================================================================== -->
    <!-- P A R E N T P R O J E C T D E S C R I P T I O N -->
    <!-- ====================================================================== -->
    <parent>
        <groupId>com.adobe.aem.events</groupId>
        <artifactId>eventhandler</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <!-- ====================================================================== -->
    <!-- P R O J E C T D E S C R I P T I O N -->
    <!-- ====================================================================== -->

    <artifactId>eventhandler-bundle</artifactId>
    <packaging>bundle</packaging>
    <name>My Project Bundle</name>

    <dependencies>
        <dependency>
            <groupId>com.day.cq</groupId>
            <artifactId>cq-search</artifactId>
            <version>5.5.4</version>
            <scope>provided</scope>
        </dependency>
          
            
        <dependency>
            <groupId>org.osgi</groupId>
            <artifactId>org.osgi.compendium</artifactId>
        </dependency>
        <dependency>
            <groupId>org.osgi</groupId>
            <artifactId>org.osgi.core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.felix</groupId>
            <artifactId>org.apache.felix.scr.annotations</artifactId>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
           
        <dependency>
         <groupId>org.apache.felix</groupId>
    
         <artifactId>org.osgi.core</artifactId>
    
         <version>1.4.0</version>
      </dependency>
          
         <dependency>
            <groupId>org.apache.sling</groupId>
            <artifactId>org.apache.sling.api</artifactId>
            <version>2.2.4</version>
            <scope>provided</scope>
        </dependency>
           
    <dependency>
    <groupId>org.apache.jackrabbit</groupId>
    <artifactId>jackrabbit-core</artifactId>
    <version>2.4.3</version>
    </dependency>
        
    <dependency>
    <groupId>org.apache.jackrabbit</groupId>
    <artifactId>jackrabbit-jcr-commons</artifactId>
    <version>2.4.3</version>
    </dependency>
    
    <dependency>
        <groupId>org.apache.sling</groupId>
        <artifactId>org.apache.sling.jcr.api</artifactId>
        <version>2.0.4</version>
      </dependency>
          
      <dependency>
         <groupId>javax.jcr</groupId>
         <artifactId>jcr</artifactId>
         <version>2.0</version>
      </dependency>
        
                
    </dependencies>

    <!-- ====================================================================== -->
    <!-- B U I L D D E F I N I T I O N -->
    <!-- ====================================================================== -->
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.felix</groupId>
                <artifactId>maven-scr-plugin</artifactId>
                <executions>
                    <execution>
                        <id>generate-scr-descriptor</id>
                        <goals>
                            <goal>scr</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.felix</groupId>
                <artifactId>maven-bundle-plugin</artifactId>
                <extensions>true</extensions>
                <configuration>
                    <instructions>
                        <Bundle-SymbolicName>com.adobe.aem.events.eventhandler-bundle</Bundle-SymbolicName>
                    </instructions>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.sling</groupId>
                <artifactId>maven-sling-plugin</artifactId>
                <configuration>
                    <slingUrl>http://${crx.host}:${crx.port}/apps/myproject/install</slingUrl>
                    <usePut>true</usePut>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-javadoc-plugin</artifactId>
                 <configuration>
                    <excludePackageNames>
                        *.impl
                    </excludePackageNames>
                 </configuration>
            </plugin>
        </plugins>
    </build>
</project>

Build the OSGi bundle using Maven

Build the OSGi bundle by using Maven. When Maven builds the bundle, it also creates a  serviceComponents.xml file based on the annotations that are included in the com.adobe.aem.sc.HandleClaimSC class. The following XML represents this file.

<?xml version="1.0" encoding="UTF-8"?>
<components xmlns:scr="http://www.osgi.org/xmlns/scr/v1.0.0">
    <scr:component enabled="true" name="com.adobe.aem.events.SimpleDSComponent">
        <implementation class="com.adobe.aem.events.SimpleDSComponent"/>
        <service servicefactory="false">
            <provide interface="java.lang.Runnable"/>
            <provide interface="javax.jcr.observation.EventListener"/>
        </service>
        <property name="service.pid" value="com.adobe.aem.events.SimpleDSComponent"/>
        <reference name="resolverFactory" interface="org.apache.sling.api.resource.ResourceResolverFactory" cardinality="1..1" policy="static" bind="bindResolverFactory" unbind="unbindResolverFactory"/>
        <reference name="repository" interface="org.apache.sling.jcr.api.SlingRepository" cardinality="1..1" policy="static" bind="bindRepository" unbind="unbindRepository"/>
    </scr:component>
</components>

There are a couple of points to note about this XML file. First, notice that the implementation class element specifies com.adobe.aem.events.SimpleDSComponent. The service element contains an interface attribute that specifies javax.jcr.observation.EventListener.

In order for the service injection to work, the reference element must be configured correctly. In this example, notice that name of the reference is resolverFactory. Also notice that it’s based on org.apache.sling.api.resource.ResourceResolverFactory, that is part of the AEM API.

To build the AEM event handler by using Maven, perform these steps:

  1. Open the command prompt and go to the C:\AdobeCQ\eventhandler folder.
  2. Run the following maven command: mvn clean install.
  3. The OSGi component can be found in the following folder: C:\AdobeCQ\eventhandler\bundle\target. The file name of the OSGi component is eventhandler-bundle-1.0-SNAPSHOT.

Deploy the bundle to Experience Manager

After you deploy the event handler, you can see it in the Experience Manager Apache Felix Web Console.

osgi

After you deploy the AEM event handler, when a new node is added under content/claim, the AEM event handler creates this log message:

17.04.2014 17:25:59.356 *INFO* [ObservationManager] com.adobe.aem.events.SimpleDSComponent A new node was added to content/claim at: Thu Apr 17 17:25:59 EDT 2014.

Note:

For testing purposes, you can use CRXDE Lite to add a node under content/claim. When you add a node of type nt:unstructured (and save the changes), the event handler logs a message in the AEM log file.  To learn how to write an AEM application that posts values to this path and trigger the event handler, see http://helpx.adobe.com/experience-manager/using/post_chars.html.

Deploy the AEM event handler by performing these steps:

  1. Login to  Apache Felix Web Console at http://server:port/system/console/bundles (default admin user = admin with password= admin).
  2. Click the Bundles tab, sort the bundle list by Id, and note the Id of the last bundle.
  3. Click the Install/Update button.
  4. Browse to the bundle JAR file you just built using Maven. (C:\AdobeCQ\eventhandler\bundle\target).
  5. Click Install.
  6. Click the Refresh Packages button.
  7. Check the bundle with the highest Id.
  8. Click Active.
  9. Your new bundle should now be listed with the status Active.
  10. If the status is not Active, check the CQ error.log for exceptions. 

Blacklist

Event handling in Sling by default may timeout your event handler. To configure your event handler to ignore a timeout, perform these tasks:

  1. Go to http://:/system/console/configMgr.
  2. Select Configuration. 
  3. Select "Apache Felix Event Admin Implementation".
  4. You should see a list for ignore timeout, specify your package in that list.

 

Viewing events

You can view AEM events by using the Events view located at: http://localhost:4502/system/console/events. 

The following illustration shows events generated when a node was added under /content/claims. 

EVENTS
An events that was created when a node was added under content/claim

See also

Congratulations, you have just created an AEM event handler by using an Adobe Maven Archetype project. Please refer to the AEM community page for other articles that discuss how to build AEM services/applications by using an Adobe Maven Archetype project.

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