Article summary

Summary

Discusses how to create a custom SlingPostProcessor that implements Interface SlingPostProcessor.  

A special thank you to Prasad Boggavarapu, a member of the AEM community for helping test this community article.

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
Tested On Adobe Experience Manager 5.5, 5.6
Prasad Boggavarapu

Introduction

You can develop a custom Sling Post Processer for Adobe Experience Manager (AEM) that is invoked after a Sling Post Servlet operation occurs. For example, assume that an Experience Manager page posts data to Experience Manager by using a Sling Post Servlet operation. That is, once the Sling Post Servlet operation makes changes to the AEM JCR, but before the changes are persistet, the custom Sling Post Processer is invoked. Using a Sling Post Processer, you can perform tasks such as creating a log of JCR node changes. A Sling Post Processer is as an OSGi bundle that implements SlingPostProcessor.

The article walks you through how to create a Sling Post Processer that is invoked when an Experience Manager mobile form submits data to AEM by using a Sling Post Servlet operation.

mobile

Setup Maven in your development environment

You can use Maven to build an AEM OSGi bundle. 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.cq  -DartifactId=postprocessor -Dversion=1.0-SNAPSHOT -Dpackage=com.adobe.cql  -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] Final Memory: 10M/184M

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

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

The sling post processor application logic is added to the PostProcesserServlet class located in the  com.adobe.cq package. Modify this class by implementing the  SlingPostProcessor interface. Application logic that you implement can be added to the process method. For information, see process method

The application logic in this class logs information in the AEM log file. The following Java code represents the SlingPostProcessor interface. 

 

package com.adobe.cq;


import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Service;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.resource.*;
import org.apache.sling.servlets.post.Modification;
import org.apache.sling.servlets.post.SlingPostProcessor;

import javax.jcr.Node;
import java.util.List;


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Component
@Service
public class PostProcesserServlet implements SlingPostProcessor {

   
	/** Default log. */
	protected final Logger log = LoggerFactory.getLogger(this.getClass());
	               
	
	@Override
    public void process(SlingHttpServletRequest request, List<Modification> changes) throws Exception {
        final Resource resource = request.getResource();
        final Node node = resource.adaptTo(Node.class); // todo adaptation to PersistableValueMap has to be considered.
        if (null != node && node.getPath().startsWith("/content")) 
            log.info("#################### Inside Sling Post Processer - under /content --  #################");
        else 
        	log.info("#################### Inside Sling Post Processer - not under /content --  #################");
        }
    }

Modify the Maven POM file 

Modify the POM files to successfully build the OSGi bundle. In the POM file located at C:\AdobeCQ\postprocessor. The following XML represents the POM file to build the custom SlingPostProcesser. 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.cq</groupId>
        <artifactId>postprocessor</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>postprocessor-bundle</artifactId>
    <packaging>bundle</packaging>
    <name>My Project Bundle</name>

    <dependencies>
        <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.commons.osgi</artifactId>
        <version>2.2.0</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>org.apache.sling</groupId>
        <artifactId>org.apache.sling.api</artifactId>
        <version>2.0.2-incubator</version>
      </dependency>    
           
      <dependency>
         <groupId>javax.jcr</groupId>
         <artifactId>jcr</artifactId>
         <version>2.0</version>
      </dependency>
  
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
    <version>2.5</version>
</dependency>
              
    <dependency>
            <groupId>com.googlecode.json-simple</groupId>
            <artifactId>json-simple</artifactId>
            <version>1.1</version>
        </dependency>
         
       <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
        </dependency>
        
        <dependency>
	<groupId>org.apache.sling</groupId>
	<artifactId>org.apache.sling.servlets.post</artifactId>
	<version>2.2.0</version>
	<scope>provided</scope>
</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.cq.postprocessor-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

To build the OSGi bundle by using Maven, perform these steps:

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

Deploy the bundle to Experience Manager

After you deploy the Experience Manager custom Sling Post Processor, when you perform a SlingPostServlet opertion, the custom Sling Post Processor logs information in the AEM log file.

14.08.2015 15:03:08.465 *INFO* [0:0:0:0:0:0:0:1 [1439578988449] POST /content/claim/newClaim_d28dc156-e57f-4081-9830-9fe1a8121361 HTTP/1.1] com.adobe.cq.PostProcesserServlet #################### Inside Sling Post Processer - not under /content --  #################

To test this custom OSGi bundle, you can use the example AEM mobile form that posts data to AEM by using a Sling Post Servlet. For information, see Using Sling Post Servlets to submit mobile data to Experience Manager

Deploy the AEM Sling Post Processor 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\postprocessor\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 PostSlingProcessor by using implementing Interface SlingPostProcessor. Please refer to the AEM community page for other articles that discuss how to build AEM services/applications.

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