 ------
 Creating Skinny Modules
 ------
 Marat Abrarov
 ------
 2020-10-18
 ------

~~ 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.

~~ NOTE: For help with the syntax of this file, see:
~~ http://maven.apache.org/doxia/references/apt-format.html

Creating Skinny Modules

 This is a bit like {{{./skinny-wars.html}skinny WARs}}, but taken to the
 next level and applied to EAR modules of type:

  * {{{../modules.html#webModule}WAR}}

  * {{{../modules.html#rarModule}RAR}}

  * {{{../modules.html#wsrModule}WSR}}

  * {{{../modules.html#sarModule}SAR}}

  * {{{../modules.html#harModule}HAR}}

 Starting with version 3.2.0, the Maven EAR Plugin supports referencing
 external JARs packaged within the EAR via the <<<Class-Path>>> setting
 in EAR module <<<MANIFEST.MF>>>.

 You need to change the EAR project's <<<pom.xml>>> to package those JARs
 in the EAR and to use the
 {{{../ear-mojo.html#skinnyModules}skinnyModules}} parameter.

 <<Note:>> In this example we package all JARs into a <<<libs/>>> directory
 within the EAR. This is just to distinguish between Java EE modules
 (which will be packaged in the root of the EAR) and Java libraries
 (which are packaged in <<<libs/>>>). Also, we use non-standard
 <<<outputFileNameMapping>>> to shorten names of files packaged
 in EAR and to keep them close to the names used in local repository
 for a better readability.

+-----------------+
<project>
  ...
  <dependencies>
    <!-- This is the JAR we want to share -->
    <dependency>
      <groupId>com.acme</groupId>
      <artifactId>shared-jar</artifactId>
      <version>1.0.0</version>
    </dependency>
    <dependency>
      <groupId>com.acme</groupId>
      <artifactId>war</artifactId>
      <version>1.0.0</version>
      <type>war</type>
    </dependency>
    <dependency>
      <groupId>com.acme</groupId>
      <artifactId>rar</artifactId>
      <version>1.0.0</version>
      <type>rar</type>
    </dependency>
    <dependency>
      <groupId>com.acme</groupId>
      <artifactId>sar</artifactId>
      <version>1.0.0</version>
      <type>sar</type>
    </dependency>
  </dependencies>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-ear-plugin</artifactId>
        <version>${project.version}</version>
        <configuration>
          <outputFileNameMapping>@{artifactId}@-@{version}@@{dashClassifier?}@.@{extension}@</outputFileNameMapping>
          <defaultLibBundleDir>libs/</defaultLibBundleDir>
          <skinnyModules>true</skinnyModules>
        </configuration>
      </plugin>
    </plugins>
  </build>
  ...
</project>
+-----------------+

 Your EAR will contain something like this:

+-----------------+
 .
 |-- META-INF
 |   `-- application.xml
 |-- libs
 |   `-- shared-jar-1.0.0.jar
 |-- war-1.0.0.war
 |-- sar-1.0.0.sar
 `-- rar-1.0.0.rar
+-----------------+

 If you look inside the copies of <<<war-1.0.0.war>>>, <<<rar-1.0.0.ear>>>
 and <<<sar-1.0.0.sar>>>, that are packaged within the EAR, you will see that
 they no longer contain <<<WEB-INF/lib/shared-jar-1.0.0.jar>>>,
 <<<shared-jar-1.0.0.jar>>> and <<<lib/shared-jar-1.0.0.jar>>> files respectively.

 Also, if you inspect the <<<MANIFEST.MF>>> of WAR, SAR and HAR modules of EAR
 you will notice that the <<<Class-Path>>> entry has been modified or added,
 if it was missing, and now has a reference to <<<libs/shared-jar-1.0.0.jar>>>.

 If an archive representing the EAR module has non-standard location of libraries,
 then this location can be configured using the <<<libDirectory>>> property.

 Here is example for SAR which contains libraries at the root of the archive
 (refer to {{{../modules.html#sarModule}sarModule}} for description of
 <<<libDirectory>>> property):

+-----------------+
<project>
  ....
  <dependencies>
    <!-- This is the JAR we want to share -->
    <dependency>
      <groupId>com.acme</groupId>
      <artifactId>shared-jar</artifactId>
      <version>1.0.0</version>
    </dependency>
    <dependency>
      <groupId>com.acme</groupId>
      <artifactId>war</artifactId>
      <version>1.0.0</version>
      <type>war</type>
    </dependency>
    <dependency>
      <groupId>com.acme</groupId>
      <artifactId>rar</artifactId>
      <version>1.0.0</version>
      <type>rar</type>
    </dependency>
    <!-- SAR having shared-jar-1.0.0.jar at the root -->
    <dependency>
      <groupId>com.acme</groupId>
      <artifactId>sar</artifactId>
      <version>1.0.0</version>
      <type>sar</type>
    </dependency>
  </dependencies>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-ear-plugin</artifactId>
        <version>${project.version}</version>
        <configuration>
          <outputFileNameMapping>@{artifactId}@-@{version}@@{dashClassifier?}@.@{extension}@</outputFileNameMapping>
          <defaultLibBundleDir>libs/</defaultLibBundleDir>
          <skinnyModules>true</skinnyModules>
          <modules>
            <sarModule>
              <groupId>com.acme</groupId>
              <artifactId>sar</artifactId>
              <libDirectory>/</libDirectory>
            </sarModule>
          </modules>
        </configuration>
      </plugin>
    </plugins>
  </build>
  ...
</project>
+-----------------+