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Friday, January 17, 2014

Creating an archetype for a multi project JEE Maven project.


Goal
To create an archetype that can be used to create multi module maven projects.
Multi project, maven projects give us the convenience of running a maven command in the base project.
So if we type mvn clean install in the  base project, the command will be executed for all the enclosed projects.


To accomplish this we first need to create  a multi module project. Then create an archetype from that project.

This blog details the following steps:
- How I created the base project
- How I generated the archetype from the base project
- How I used the archetype to create my first mult project maven project

Base multi module project








The Archetype

Here is the directory structure of the final archetype. As you can see the actual archetype will be found under target/generated-resources folder.






The idea was to install this archetype in the company repository and all new projects will use this archetype to create its project structure.

Example of a project that was created using the above shown archetype.
As you can see the __rootArtifactId__ token is replaced with the actual project name.
Which in this case is acctauthreq

Sample Project using the archetype






Okay, time to go over the steps that  I went through to get the archetype going.

Creating the Base Project

Base project is the enclosing project. Here is the command  I used to generate it. I have decided to call the base project for the archetype adi-identity-archetype.

mvn archetype:create -DarchetypeGroupId=org.apache.maven.archetypes -DarchetypeArtifactId=maven-archetype-quickstart -DgroupId=edu.vanderbilt.adi -DartifactId=adi-identity-archetype -Dversion=1.0


As you can see the maven-archetype-quickstart was used to create the base project.

 Running the above command will create a folder
adi-identity-archetype and a pom.xml with packaging type jar.


Cd to adi-identity-archetype and change the pom.xml packaging type to pom.

 













Also add dependencies to java ee, commons logging etc.
<dependency> 
      <groupId>javaee</groupId> 
      <artifactId>javaee-api</artifactId> 
      <version>5</version> 
      <scope>provided</scope> 
</dependency>

<dependency>
  <groupId>commons-logging</groupId>
  <artifactId>commons-logging</artifactId>
  <version>1.1.1</version>
</dependency>



All the other maven projects will created inside this enclosing Base Project.

Creating the internal projects

Step 1: CD to adi-identity-archetype

Step 2: Create util project

Run the following command.



mvn archetype:create -DarchetypeGroupId=org.apache.maven.archetypes -DarchetypeArtifactId=maven-archetype-quickstart -DgroupId=edu.vanderbilt.adi.util -DartifactId=__rootArtifactId__-util  -Dversion=1.0


As you can see the artifactId is __rootArtifactId__-util.


Step 3: Create EJB project



mvn archetype:create -DarchetypeGroupId=org.apache.maven.archetypes -DarchetypeArtifactId=maven-archetype-quickstart -DgroupId=edu.vanderbilt.adi.ejb -DartifactId=__rootArtifactId__-ejb  -Dversion=1.0

CD to __rootArtifactId__-ejb 

 Then enter the relative path to the parent pom. The pom.xml of the enclosing Base Project will be the parent pom.







Set Packaging to
<packaging>ejb</packaging>



Add the following plugins



Add the following dependencies

 



Step 4: Create Web project.
We use a struts based web project and thus used the struts2-archetype-blank to create the web project.

If you do not care for struts you could use the maven-archetype-webapp to create the web project.


Here is the command I used to create a struts based web app.

mvn archetype:generate -DgroupId=edu.vanderbilt.adi.web  -DartifactId=__rootArtifactId__-war  -Dversion=1.0 -DarchetypeGroupId=org.apache.struts   -DarchetypeArtifactId=struts2-archetype-blank -DarchetypeVersion=2.1.8.1 -DarchetypeCatalog=http://people.apache.org/builds/struts/2.1.8.1/m2-staging-repository/


Add the relative path to the parent pom and change the packaging to war.
 Since we want to filter the web.xml we would need to configure the maven war plugin.





Since we do not use spring and jetty remove explicit dependencies to these jars.



Step 5: Create EAR project
Most of our applications are eventually packaged in an ear. Thus creating a packaging ear project.



mvn archetype:create -DarchetypeGroupId=org.apache.maven.archetypes -DarchetypeArtifactId=maven-archetype-quickstart -DgroupId=edu.vanderbilt.adi.ear -DartifactId=__rootArtifactId__-ear  -Dversion=1.0

Cd to __rootArtifactId__-ear
 Then enter the relative path to the parent pom. The pom.xml of the enclosing Base Project will be the parent pom.

 

  Change the packaging from jar to ear.



saa

 Add the following dependencies. The other internal projects are being added here as dependencies.



  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>

    <dependency>
     <groupId>${groupId}.util</groupId>
          <artifactId>__rootArtifactId__-util</artifactId>
           <version>1.0</version>
           <type>jar</type>
    </dependency>
    <dependency>
      <!-- 3.3. Dependency on EJB Module. -->
            <groupId>${groupId}.ejb</groupId>
            <artifactId>__rootArtifactId__-ejb</artifactId>
           <type>ejb</type>
           <version>1.0</version>
    </dependency>
    <dependency>
      <!-- 3.4. Dependency on Web Application Module. -->
            <groupId>${groupId}.web</groupId>
            <artifactId>__rootArtifactId__-war</artifactId>
           <type>war</type>
     <version>1.0</version>
    </dependency>
  </dependencies>


Configure the maven ear plugin as follows:

 

<plugins>
<plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-ear-plugin</artifactId>
        <configuration>
          <!-- 4.5. Specify modules to include. -->
         <modules>
            <!-- 4.5.1. Include Java Module. -->
            <javaModule>
            <groupId>${groupId}.util</groupId>
          <artifactId>__rootArtifactId__-util</artifactId>
           </javaModule>
            <!-- 4.5.2. Include EJB Module. -->
            <ejbModule>
          <groupId>${groupId}.ejb</groupId>
            <artifactId>__rootArtifactId__-ejb</artifactId>
            </ejbModule>
            <!-- 4.5.3. Include Web Application Module. -->
            <webModule>
            <groupId>${groupId}.web</groupId>
            <artifactId>__rootArtifactId__-war</artifactId>
           <contextRoot>${webContext}</contextRoot>          
            </webModule>
          </modules>
        </configuration>
      </plugin>
</plugins>



*Note specifying the webcontext as shown here will allow the user to specify the webcontext on demand during build. See Ex. below.



If the <contextRoot>${webContext}</contextRoot> is added in the maven ear plugin on mvn install you can pass in the required web context as a parameter






sds



And the resuting application.xml will have this value as the web context.






 Step 6: Create Model
We use EJB3 and JPA entities (implemented as Hibernate entities) and hence creating  a model project.


mvn archetype:create -DarchetypeGroupId=org.apache.maven.archetypes -DarchetypeArtifactId=maven-archetype-quickstart -DgroupId=edu.vanderbilt.adi.model -DartifactId=__rootArtifactId__-model -Dversion=1.0

  CD to __rootArtifactId__-model
 Then enter the relative path to the parent pom. The pom.xml of the enclosing Base Project will be the parent pom.
sad

Add the following dependencies to hibernate.


<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.0-api</artifactId>
<version>1.0.1.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>4.0.1.Final</version>
</dependency>


Under folder __rootArtifactId__-model\src\main create folder resources


 







Under the resources folder create persistence.xml





Under __rootArtifactId__-model\src\main\java\edu\vanderbilt\adi\model create SampleEntity.java