Question

I develop a webapp using a model-view-controller pattern. The model package represents the core API of the application, that could be used independently. The controller and view packages use the model package to produce a webapp.

Question:
I’d like to be able to build a JAR of only the model package, and a WAR of the three packages. And I’d like to keep the three packages in a same project. The webapp WAR would include supplementary libraries as compared to the standalone JAR.
How could I achieve this with Maven? Would there be a solution using for instance two separate pom.xml files? (because as far as I know, you cannot choose two packaging options in the pom.xml)

(I’ve seen this question, but I really want my three packages to be part of a same project, and be part of the same directory.)

Also, my project uses a classical webapp structure (simplified here):

my-app
-- pom.xml
-- src
----- main/
-------- java/
----------- model/
----------- view/
----------- controller/
-------- webapp/
---------- WEB-INF/
-------------classes/

Could I manage to generate the JAR in the classical target/ directory, and the webapp in the classical src/main/webapp/ directory? (and, as asked, including different libraries)

Thanks for your help.

Answer 1

Take a look at Maven Assembly Plugin.

With it you can have as many different Assembly Descriptors as you need, each one customized with its own packaging scheme, filesets and dependencies.

---

Here is a sample plugin configuration for your pom.xml:

<build>
  <plugins>
     <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>2.4</version>
        <configuration>
            <descriptors>
               <descriptor>src/main/assembly/model.xml</descriptor>
            </descriptors>
        </configuration>
     </plugin>
  </plugins>
</build>

And a sample assembly descriptor for the model jar (src/main/assembly/model.xml)

<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0 http://maven.apache.org/xsd/assembly-1.1.0.xsd">
  <id>model</id>
  <formats>
    <format>jar</format>
  </formats>
  <includeBaseDirectory>false</includeBaseDirectory>
  <fileSets>
    <fileSet>
      <directory>${project.build.outputDirectory}/model</directory>
      <outputDirectory>/</outputDirectory>
      <includes>
        <include>**/*</include>
      </includes>
    </fileSet>
  </fileSets>
</assembly>

Running mvn clean package assembly:single will generate both the standard my-app.war file from your project pom.xml and a my-app-model.jar in the target package.