Question

I have Maven project with a parent module and two children: Service and API. The Service module is a WAR and contains all of the source files for the project, while the API module exists purely to build a jar containing a subset of classes from the Service module, and to deploy that jar to a local maven repo.

I’ve tried a combo of the maven-dependency-plugin and the maven-assembly-plugin to copy over the Service war and include it in the deployed API JAR, but I’m struggling to find a way to pull in just a specific set of classes from the Service module without roping in the entire fat WAR.

From API‘s pom.xml:

<plugins>
  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-dependency-plugin</artifactId>
    <executions>
      <execution>
        <id>copy-dependencies</id>
        <phase>package</phase>
        <goals>
          <goal>copy-dependencies</goal>
        </goals>
        <configuration>
          <excludeGroupIds>...</excludeGroupIds>
          <outputDirectory>${project.build.directory}/lib</outputDirectory>
        </configuration>
      </execution>
    </executions>
  </plugin>
  <plugin>
    <artifactId>maven-assembly-plugin</artifactId>
    <executions>
      <execution>
        <goals>
          <goal>single</goal>
        </goals>
        <phase>package</phase>
      </execution>
    </executions>
    <configuration>
      <descriptors>
        <descriptor>assembly.xml</descriptor>
      </descriptors>
    </configuration>
  </plugin>
</plugins>

I’ve thought about building the slim JAR using the maven-jar-plugin from the Service module’s pom, but this seems like bad practice. Suggestions?

Answer 1

You should rather take out the implementation details from the war and put in a separate module.

.
├── pom.xml
├── service-api
|   ├── pom.xml
|   └── src
|       └── main
|           └── java
|               └── com
|                   └── stackoverflow
|                       └── SomeDao.java
├── service-impl
|   ├── pom.xml
|   └── src
|       └── main
|           └── java
|               └── com
|                   └── stackoverflow
|                       └── SomeDaoImpl.java
└── service-web
    ├── pom.xml
    └── src
        └── main
            └── webapp
                └── WEB-INF
                    └── web.xml

Let service-impl depend on service-api. And service-web will depend on the service-impl.