Article summary

Summary

Discusses how to create a custom DAM media handler that responds to digital assets being uploaded to the AEM DAM.

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.

Digital Marketing Solution(s) Adobe Experience Manager (Adobe CQ)
Audience
Developer (intermediate)
Required Skills
Java, Maven, JCR, Sling
Version Adobe Experience Manager 5.5,5.6, 6.x 
Video https://youtu.be/AEIq759seq8

Introduction

You can create a custom Adobe Experience Manager (AEM) DAM media handler that is invoked when you upload a digital asset to the AEM DAM. A DAM media handle processes a digital asset when it’s uploaded to the AEM DAM. For example, an DAM handler can generate a thumbnail generation and extract metadata.

DamHandler

This development article guides you through creating an AEM DAM media handler that responds to a digital asset being uploaded to the AEM DAM. Application logic that represents a custom DAM media handler is implemented as an OSGi bundle that is built using Maven. The OSGi bundle contains a class that extends com.day.cq.dam.commons.handler.AbstractAssetHandler. For information, see AbstractAssetHandler.

To create an AEM DAM media handler, perform these tasks:

Setup Maven in your development environment

You can use Maven to build an OSGi bundle that contains a DAM media handler. 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.dam -DartifactId=damhandler -Dversion=1.0-SNAPSHOT -Dpackage=com.adobe.dam -DappsFolderName=myproject -DartifactName="My Project" -DcqVersion="5.6.1" -DpackageGroup="My Company"

3. When prompted for additional information, 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\damhandler.

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 damhandler-bundle project. You can delete the damhandler-content project from the Eclipse IDE. Besure to work in the scr/main/java folder as opposed to the src/test/java folder.  Finally delete all default JAVA files in this package. 

The next step is to add a Java file to the com.adobe.dam package that extends com.day.cq.dam.commons.handler.AbstractAssetHandler. This class represents the basis for the dam media handler and provides common functionality. Create a class named MyHandler that extends AbstractAssetHandler. For information, see AbstractAssetHandler.

To ensure that your custom DAM media handler is called, and not the default ones that are available with AEM, you can use Constants.SERVICE_RANKING value. Set the intValue value to an integer value. The priority is given to the higher value, as shown in this code example.

@Component
@Service

@Properties({
    @Property(name = Constants.SERVICE_RANKING , intValue = 100) })

public class MyHandler extends AbstractAssetHandler {

Note:

For CQ 5.5, set the rank to -100.

Because MyHandler extends AbstractAssetHandler, create a method named extractMetadata. This method is invoked by the ExtractMetadataProcess, which is part of the DAM Update Asset workflow during import or update of a digital asset. This method returns a com.day.cq.dam.api.metadata.ExtractedMetadata object, which may be empty if no metadata is extracted, or contains the metadata values extracted from the binary being imported/updated at the time. You can define application logic that specifies which and how many metadata values are extracted.

The parameter that is passed to the extractMetadata method is a com.day.cq.dam.api.Asset object. This value represents the digital asset that is uploaded to the AEM DAM.   

public ExtractedMetadata extractMetadata(com.day.cq.dam.api.Asset asset)

To extract metadata, convert the Asset to a Node, invoke the getInputStream method, and pass the Node, as shown in the following code.

public ExtractedMetadata extractMetadata(com.day.cq.dam.api.Asset asset)
{
ExtractedMetadata extractedMetadata = new ExtractedMetadata();

//Convert the asset to a node to get an InputStream
Node node = asset.adaptTo(Node.class);
InputStream data = this.getInputStream(node);

Once you have an InputStream object that represents the uploaded digital asset, you can perform various tasks. For example, you can retrieve the text located in the digital asset, as shown in the following code.

InputStream data = this.getInputStream(node);
long wordCount = 0;
try {
// read text data

InputStreamReader reader = new InputStreamReader(data);
char[] buffer = new char[4096];
String text = "";
while (reader.read(buffer) != -1) {
    text += new String(buffer);
}

You can use the text value to set the ExtractedMetaData object's text property by invoking its setProperty method.  

extractedMetadata.setProperty("text", text);  

To determine what type of ditigal asset your DAM media handler responds to, define the getMimeTypes method, as shown in this code example.

/** * @see com.day.cq.dam.api.handler.AssetHandler#getMimeTypes() */
public String[] getMimeTypes() {
    return new String[] {"text/plain"};
}

This method returns a String array of MIME types that your DAM handler responds to. In this example, the DAM handler responds to a digital asset with a MIME type of text/plain.  

The following Java code represents the entire MyHandler class. Copy this Java code to your MyHandler file.  

package com.adobe.dam;

import java.awt.Color; 
import java.awt.Rectangle; 
import java.awt.image.BufferedImage; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import javax.jcr.Node; 
import javax.jcr.RepositoryException; 
import javax.jcr.Session; 
import org.apache.commons.io.IOUtils; 
import org.slf4j.Logger; 
import org.slf4j.LoggerFactory; 

import com.day.cq.dam.api.metadata.ExtractedMetadata; 
import com.day.cq.dam.commons.handler.AbstractAssetHandler;
import com.day.cq.dam.api.handler.AssetHandler;
import com.day.image.Font; 
import com.day.image.Layer; 
import com.day.cq.wcm.foundation.ImageHelper; 

import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Service;
import org.apache.felix.scr.annotations.Properties;
import org.apache.felix.scr.annotations.Property;
import org.osgi.framework.Constants;

@Component
@Service

@Properties({
  @Property(name = Constants.SERVICE_RANKING , intValue  = 100) })

public class MyHandler extends AbstractAssetHandler  { 
    
	/** * Logger instance for this class. */
	protected final Logger log = LoggerFactory.getLogger(this.getClass());
    
    /** * Music icon margin */
    private static final int MARGIN = 10; 
    
    /** * @see com.day.cq.dam.api.handler.AssetHandler#getMimeTypes() */
    public String[] getMimeTypes() {
        return new String[] {"text/plain"}; 
    }

    public ExtractedMetadata extractMetadata(com.day.cq.dam.api.Asset asset)
    {
 	ExtractedMetadata extractedMetadata = new ExtractedMetadata(); 
 	
 	//convert  the asset to a node to that we can get an InputStream
	Node node = asset.adaptTo(Node.class); 
    InputStream data = this.getInputStream(node); 
    long wordCount = 0;  
    try { 
        // read text data 
    	
    	InputStreamReader reader = new InputStreamReader(data); 
        char[] buffer = new char[4096]; 
        String text = ""; 
        while (reader.read(buffer) != -1) { 
            text += new String(buffer); 
        } 
        reader.close(); 
        wordCount = this.wordCount(text); 
        extractedMetadata.setProperty("Title", "Text File"); 
        extractedMetadata.setProperty("text", text); 
        extractedMetadata.setMetaDataProperty("Word Count",wordCount); 
        setMimetype(extractedMetadata, asset); 
    } catch (Throwable t) { 
        log.error("handling error: " + t.toString(), t); 
    } finally { 
        IOUtils.closeQuietly(data); 
        //Log the number of words in the Digial Assets uploaded to the DAM
        log.info("Here in the DAM Hander - the text asset had this many words "+wordCount);
    } 
 	return extractedMetadata; 
    }
   
      
       
    
     
/**
 * This method counts the number of words in a string
 *
 * @param text the String whose words would like to be counted
 @return the number of words in the string
 */
 private long wordCount(String text) {
 // We need to keep track of the last character, if we have two white spaces in a row we dont want to double count 
 // The starting of the document is always a whitespace 
 boolean prevWhiteSpace = true;
 boolean currentWhiteSpace = true;
 char c;
 long numwords = 0;
 int j = text.length();
 int i = 0;
 while (i < j) {
	 c = text.charAt(i++);
	 if (c == 0) { break; }
	 currentWhiteSpace = Character.isWhitespace(c);
	 if (currentWhiteSpace && !prevWhiteSpace)
	 	{ numwords++; }
	 prevWhiteSpace = currentWhiteSpace;
 	} // If we do not end with a white space then we need to add one extra word 
 if (!currentWhiteSpace) 
 	{ numwords++; }
 return numwords;
 }
 
     
      
     
     //
    // This method cuts lines if the text file is too long..
     //*
     //* @param text * text to check
     //@param height * text box height (px)
     //@param fontheight * font height (px)
     //@return the text which will fit into the box
     
     private String getDisplayText(String text, int height, int fontheight) {
    	 String trimmedText = text.trim();
    	 int numOfLines = height / fontheight;
    	 String lines[] = trimmedText.split("\n");
     
    	 	if (lines.length <= numOfLines) { return trimmedText; }
    	 	else {
    	 			StringBuilder cuttetTextBuilder = new StringBuilder();
    	 			for (int i = 0; i < numOfLines; i++)
    	 			{ cuttetTextBuilder.append(lines[i]).append("\n"); }
    	 	return cuttetTextBuilder.toString();
    	 	}
     }  
      
     @Override
     protected BufferedImage getThumbnailImage(Node node) {
    	 ExtractedMetadata metadata = extractMetadata(node);
    	 final String text = (String) metadata.getProperty("text");
    	 // create text layer 
    	 final Layer layer = new Layer(500, 600, Color.WHITE);
    	 layer.setPaint(Color.black);
    	 Font font = new Font("Arial", 12);
    	 String displayText = this.getDisplayText(text, 600, 12);
    	 if (displayText != null && displayText.length() > 0)
    	 { // commons-gfx Font class would throw IllegalArgumentException on empty or null text layer.drawText(10, 10, 500, 600, displayText, font, Font.ALIGN_LEFT, 0, 0); }
    		 // create watermark and merge with text layer 
    		 
    		 Layer watermarkLayer;
    		 try
    		 { 
    		  final Session session = node.getSession();
    		  watermarkLayer = ImageHelper.createLayer(session, "/content/dam/geometrixx/icons/certificate.png"); 
    		  watermarkLayer.setX(MARGIN); watermarkLayer.setY(MARGIN); 
    		  layer.merge(watermarkLayer); 
    		 }
    		 catch (Exception e)
    	     {  
    	    	 e.printStackTrace();
    	     }
    	}
     
     layer.crop(new Rectangle(510, 600));
     return layer.getImage();
     }
     
       
}

Note:

When this DAM media handler is invoked, it logs this message in the AEM log file: com.adobe.handle.MyHandler Here in the DAM Hander - the text asset had this many words 2932.

Modify the Maven POM file 

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

  • org.apache.felix.scr
  • org.apache.felix.scr.annotations
  • com.day.cq.dam.api.metadata.ExtractedMetadata
  • com.day.cq.dam.commons.handler.AbstractAssetHandler

Note:

Modify the POM file that appears in the Eclipse project.  

The following XML represents the POM file to build the custom DAM media 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.dam</groupId>
        <artifactId>damhandler</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>damhandler-bundle</artifactId>
    <packaging>bundle</packaging>
    <name>My Project Bundle</name>

    <dependencies>
         
               
         <dependency>
			<groupId>com.day.cq.dam</groupId>
			<artifactId>cq-dam-api</artifactId>
			<version>5.6.4</version>
			<scope>provided</scope>
		</dependency>
        
       <dependency>
		<groupId>com.day.cq</groupId>
		<artifactId>cq-commons</artifactId>
		<version>5.6.2</version>
		<scope>provided</scope>
	</dependency>
   
        <dependency>
            <groupId>com.day.cq.dam</groupId>
            <artifactId>cq-dam-core</artifactId>
            <version>5.5.0</version>
             <scope>provided</scope>
             </dependency>
             
          <dependency>
			<groupId>com.day.cq.dam</groupId>
			<artifactId>cq-dam-commons</artifactId>
			<version>5.6.6</version>
				<scope>provided</scope>
		</dependency>   
         
                      
       	         
                <dependency>
            <groupId>org.apache.sling</groupId>
            <artifactId>org.apache.sling.jcr.resource</artifactId>
            <version>2.3.4</version>
        </dependency>
           
        <dependency>
            <groupId>com.day.cq</groupId>
            <artifactId>cq-search</artifactId>
            <version>5.5.4</version>
         </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>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>
             
        </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>
 
    <dependency>
            <groupId>com.day.commons</groupId>
            <artifactId>day-commons-gfx</artifactId>
            <version>2.1.4</version>
            </dependency>
         
         <dependency>
            <groupId>com.day.cq.wcm</groupId>
            <artifactId>cq-wcm-foundation</artifactId>
            <version>5.5.2</version>
            
        </dependency>
         
         <dependency>
            <groupId>com.day.cq.dam</groupId>
            <artifactId>cq-dam-api</artifactId>
            <version>5.5.0</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.dam.damhandler-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.dam.MyHandler 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.dam.SimpleDSComponent">
        <implementation class="com.adobe.dam.SimpleDSComponent"/>
        <service servicefactory="false">
            <provide interface="java.lang.Runnable"/>
        </service>
        <property name="service.pid" value="com.adobe.dam.SimpleDSComponent"/>
    </scr:component>
    <scr:component enabled="true" name="com.adobe.dam.MyHandler">
        <implementation class="com.adobe.dam.MyHandler"/>
        <service servicefactory="false">
            <provide interface="com.day.cq.dam.api.handler.AssetHandler"/>
        </service>
        <property name="service.ranking" type="Integer" value="100"/>
        <property name="service.vendor" type="String" value="Day Management AG"/>
        <property name="service.pid" value="com.adobe.dam.MyHandler"/>
        <reference name="jcrResolverFactory" interface="org.apache.sling.jcr.resource.JcrResourceResolverFactory" cardinality="1..1" policy="static" bind="bindJcrResolverFactory" unbind="unbindJcrResolverFactory"/>
        <reference name="imageCache" interface="com.day.cq.dam.api.cache.BufferedImageCache" cardinality="1..1" policy="static" bind="bindImageCache" unbind="unbindImageCache"/>
    </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.dam.MyHandler. The provide attribute specifies com.day.cq.dam.api.handler.AssetHandler (this is because this is the base interface for DAM asset handlers).  

To build the DAM media handler by using Maven, perform these steps:

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

Deploy the bundle to Experience Manager

After you deploy the DAM media handler, you can see it in the Apache Felix Web Console.

osgi

After you deploy the AEM DAM media handler, when a digital asset with a MIME type of text/plain is uploaded to the AEM DAM, the DAM media handler creates this log message:

com.adobe.handle.MyHandler Here in the DAM Hander - the text asset had this many words 2932

Note:

For testing purposes, upload a text file to the AEM DAM. 

Deploy the DAM media 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\damhandler\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. 

See also

Congratulations, you have just created an AEM DAM 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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