Building an Application

The Basics

For the most basic application in AEM, there are 2 main pieces of code, the jcr:repository and the java code. To keep things clean we do create a few more projects so that each one has it's own distinct purpose.

The following code examples won't actually do much but I will try to discuss what they are meant to be doing and why I have built them the way I have. This will be far from an extensive and in-depth view of what can and can't be built with AEM.

Maven

While you can use any build tool to create and build an aem project, maven comes with plugins for deploying to AEM as well as setting up your packages with the right information. To create a project from scratch I tend to copy an existing one, however, you can create one with the maven archetype

Project Structure

The default structure from the archetype is slightly different from what I use and I will explain.

Maven project structure

As you can see there are not that many changes. The archetype creates it. launcher project with some basic sling base test classes which I have never used.

I also add a sling project for sling mappings, with a sub-project for each of the environments. While in normal practice you would just put the sling mappings in the ui.app project, if you are using reverse mappings in the sling then it will take the first mapping that matches the folder structure and return the address as that of the server defined. I also find it quite messy having an environment that has all of the sling mappings for all possible environments.

I also have an all project that allows me to package the entire application into a single deployment within AEM.

You will notice in the structure of the pages that I don't have a section to discuss the sling and all projects, as these are variations of the ui.apps project they will be discussed in the appropriate sections of the pages on ui.apps

I know using a project for configuration is probably a bit of overkill, but it leaves your servers in a cleaner state and only code that is really needed is unpacked.

pom.xml

Most of the pom.xml files are pretty standard, having a parent pom means you can put dependency management in for the entire project which is much tidier.

There are 2 main types of package types use in aem

The code bundle that will be installed

content-package

The content and application configuration files

For building AEM apps there are a few plugins that are very useful.

org.apache.felix:maven-bundle-plugin

This plugin creates the maven bundles' information in the manifest. For more information visit the documentation page

This is mainly for creating your code project and is not really required in the other projects.

The following instructions are part of the configuration

Export-Package

Defines the packages to be declared as part of the project for AEM

Private-Package

Defines a list of packages that should not be exported

Include-Resource

Adds resources to the bundle in the root of the bundle

Import-Package

Defines a list of packages that are required by this bundle

Embed-Dependency

Defines which dependencies should be installed inside the bundle

Embed-StripVersion

Removes the version from the files

Embed-StripGroup

Removes the group as a subdirectory

Embed-Directory

Defines the directory to add artifacts to

Embed-Transitive

Check for transitive dependencies

obrRepository

The path to the OBR Repository

com.day.jcr.vault:content-package-maven-plugin

The maven vault plugin is used to create a deployable AEM package. For more information visit the documentation page

This will be used for your ui.app project, but will also be used in the ui.content and all projects.

The following instructions are some of the more important parts of the configuration

failOnError

Specifies if the build should fail if the plugin detects an error during installation of the package

name

The name of the package to act on

password

The password used for authentication with crx

serverid

The server id from which to retrieve the username and password

targetURL

The url to the crx server

timeout

The time to wait before failing the build

useProxy

Determines if the plugin should use a proxy

userId

The user id for the crx server

verbose

How the plugin logs
The version of the artefact to install

embeddeds

The way of adding additional content to the project

Use this to add the java code package to the deploy

A list of embeded items (must be in the dependencies of the project)

groupId

The group of the embedded item

artifactId

The artifact of the embedded item

target

The location in the jcr:repository to install the artefact

properties

acHandling

clear

Clears all ACL's

ignore

Ignores ACL's in the package

merge

Merges the ACL's in the package with those already on the system by replacing entries of corresponding principals

merge_preserve

Merges the ACL's in the package with those already on the system by adding for principals not already there

overwrite

Overwrite any ACL's already in place

The following is an example base pom.xml

<?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>
<groupId>com.sample</groupId>
<artifactId>base</artifactId> <name>Base</name>
<description>Sample base</description>
<packaging>pom</packaging>
<version>1.0.0-SNAPSHOT</version>
<modules>

<module>core</module>
<module>ui.apps</module>
<module>ui.content</module>
<module>sling</module>
<module>all</module>

</modules>
<properties>

<crx.user>admin</author.user>
<crx.password>admin</author.password>
<author.url>localhost:4502</author.url>
<publisher.url>localhost:4503</publisher.url>

</properties>
<build>

<plugins>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-release-plugin</artifactId>
<version>2.5.1</version>
<configuration>

<scmCommentPrefix>[maven-scm] :</scmCommentPrefix>
<preparationGoals>clean install</preparationGoals>
<goals>install</goals>
<releaseProfiles>release</releaseProfiles>

</configuration>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-source-plugin</artifactId>
<version>2.4</version>
<inherited>true</inherited>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<configuration>

<encoding>UTF-8</encoding>

</configuration>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.5</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-enforcer-plugin</artifactId>
<executions>

<execution>

<id>enforce-maven</id>
<goals>

<goal>enforce</goal>

</goals>
<configuration>

<rules>

<requireMavenVersion>

<version>[2.2.1,)</version>

</requireMavenVersion>
<requireJavaVersion>

<message>Project must be compiled with Java 8 or higher</message>
<version>1.8.0</version>

</requireJavaVersion>

</rules>

</configuration>

</execution>

</executions>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>

</configuration>

</plugin>

</plugins>
<pluginManagement>

<plugins>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-clean-plugin</artifactId>
<version>2.6.1</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<version>2.7</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.2</version>

</plugin>  <plugin>

<groupId>org.apache.felix</groupId>
<artifactId>maven-scr-plugin</artifactId>
<version>1.20.0</version>
<executions>

<execution>

<id>generate-scr-scrdescriptor</id>
<goals>

<goal>scr</goal>

</goals> <configuration>

<properties>

<service.vendor>Adobe</service.vendor>

</properties>

</configuration>

</execution>

</executions>
<configuration>

<outputDirectory>${project.build.directory}/classes</outputDirectory>

</configuration>
<dependencies>

<dependency>

<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.5.11</version>

</dependency>

</dependencies>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.18.1</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-failsafe-plugin</artifactId>
<version>2.18.1</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>

</plugin>

<plugin>

<groupId>com.day.jcr.vault</groupId>
<artifactId>content-package-maven-plugin</artifactId>
<version>0.0.24</version>
<configuration>

<targetURL>http://${aem.host}:${aem.port}/crx/packmgr/service.jsp</targetURL>
<failOnError>true</failOnError>
<failOnMissingEmbed>true</failOnMissingEmbed>

</configuration>

</plugin>

<plugin>

<groupId>org.apache.felix</groupId>
<artifactId>maven-bundle-plugin</artifactId>
<version>2.5.3</version>
<inherited>true</inherited>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-enforcer-plugin</artifactId>
<version>1.4</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.10</version>

</plugin>

<plugin>

<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>1.9.1</version>

</plugin>

</plugins>

</pluginManagement>

</build>



<dependencyManagement>

<dependencies>

<dependency>

<groupId>org.apache.felix</groupId>
<artifactId>org.apache.felix.scr</artifactId>
<version>1.6.0</version>
<scope>provided</scope>

</dependency> <dependency>

<groupId>org.apache.felix</groupId>
<artifactId>org.apache.felix.scr.annotations</artifactId>
<version>1.9.6</version>
<scope>provided</scope>

</dependency>
<dependency>

<groupId>javax.jcr</groupId>
<artifactId>jcr</artifactId>
<version>2.0</version>
<scope>provided</scope>

</dependency>
<dependency>

<groupId>com.adobe.aem</groupId>
<artifactId>uber-jar</artifactId>
<version>6.2.0</version>
<classifier>apis</classifier>
<scope>provided</scope>

</dependency>
<dependency>

<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.models.api</artifactId>
<version>1.2.2</version>
<scope>provided</scope>

</dependency>
<dependency>

<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.models.impl</artifactId>
<version>1.2.2</version>
<scope>provided</scope>

</dependency>
<dependency>

<groupId>org.apache.geronimo.specs</groupId>
<artifactId>geronimo-atinject_1.0_spec</artifactId>
<version>1.0</version>
<scope>provided</scope>

</dependency>

<dependency>

<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.4</version>
<scope>provided</scope>

</dependency>

<dependency>

<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.5.11</version>
<scope>provided</scope>

</dependency>
<dependency>

</dependency>

<dependency>

<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.4</version>
<scope>provided</scope>

</dependency>
<dependency>

<groupId>commons-collections</groupId>
<artifactId>commons-collections</artifactId>
<version>3.0</version>

</dependency>
<dependency>

<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.6</version>
<scope>provided</scope>

</dependency>
<dependency>

<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.4</version>
<scope>provided</scope>

</dependency>
<dependency>

<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.2.4</version>
<scope>compile</scope>

</dependency>
<dependency>

<groupId>org.apache.commons</groupId>
<artifactId>commons-email</artifactId>
<version>1.2</version>

</dependency>

<dependency>

<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>

</dependency>
<dependency>

<groupId>org.mockito</groupId>
<artifactId>mockito-all</artifactId>
<version>1.9.5</version>
<scope>test</scope>

</dependency>

</dependencies>

</dependencyManagement>

</project>

It isn't much unusual in the base pom, it defines all of the dependencies for libraries and plugins that the child projects will use

One thing you will notice in the dependencies is that I am using the AEM uber jar with a classifier of apis instead of obfuscated. You will need to contact adobe to get access to this file, however, it will be worthwhile as you will be able to write unit tests for all of your classes that use some of the more low-level adobe libraries. The obfuscated version doesn't include the constructors for a lot of the items which means you won't be able to mock them in your unit tests.

AEM Tutorials for Beginners

May 13, 2020
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