The ‘problem’ with a multi-module parent pom is that, without complicated profiles, it locks the modules in the same release cycle (assuming you’re using the Release Plugin, which you should be).
The way I work with Maven is to have a parent pom that declares:
- common dependencies (logging APIs, JUnit, etc).
- common plugins.
- all dependencies in the
dependencyManagement
section. - all plugins in the
pluginManagement
section.
Each module delcares the parent pom as its parent but the parent knows nothing about the modules.
The benefit of this comes from the last to two bullets above, the ‘management’ sections. Anything contained in a ‘management’ section needs to be redeclared in a module that wants to use a particular dependency or plugin.
For example the parent might look like this:
<project>
<groupId>com.example</groupId>
<artifactId>parent</artifactId>
<version>1.0.00-SNAPSHOT</version>
...
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.7</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
<version>2.6</version>
</dependency>
<dependency>
<groupId>commons-collections</groupId>
<artifactId>commons-collections</artifactId>
<version>2.1</version>
</dependency>
</dependencyManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugins>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.4</version>
<configuration>
<appendAssemblyId>false</appendAssemblyId>
<descriptors>
<descriptor>src/main/assembly/assembly.xml</descriptor>
</descriptors>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</pluginManagement>
</project>
And the module might look like this:
<project>
<parent>
<groupId>com.example</groupId>
<artifactId>parent</artifactId>
<version>1.0.00-SNAPSHOT</version>
</parent>
<groupId>com.example</groupId>
<artifactId>module</artifactId>
<version>1.0.00-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
</dependency>
</dependencies>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
</plugin>
</plugins>
</project>
The module would:
- have dependencies on
org.slf4j:slf4j-api:1.7.7:compile
,junit:junit:4.11:test
andcommons-lang:commons-lang:2.6:compile
. - has the plugin
org.apache.maven.plugins:maven-assembly-plugin:2.4