Why breaking down a Maven project to sub-modules?

Question

What are the main possible reasons of breaking down a Maven project to sub-modules?

Answer 1

Are you looking something more than the benefits of Modularization? The sub-modules should ideally be representing a single concept/feature so that they are functionally cohesive.

Answer 2

• Pom file inheritence You can use the and sections of the root poms to keep consistent version numbers and configurations across all child projects. So if I have an aggregator project that lists 300 projects, all that use apache commons-io and I want to upgrade them all the the latest version of commons-io, I can just change the version in the dependencyManagement section of the root pom. None of the child projects need specify a version.
• build profiles In the above example, if I have 300 sub projects, an individual developer is probably not regularly working on all (or even many) of the 300 sub-projects. You can create a build profile that specifies only the modules you work on regularly, and if you have a continuous integration server that deploys artifacts to an artifact repository, you'll get all the changes the developers on your team make too, without having to build all 300 modules.
• General organization/clarity

Answer 3

While waiting for an answer to my comment.

• A reason to split a Java EE based maven project into sub modules is so you can build the JAR/RAR/WAR/EAR/whatever independently of eachother.

• For regular Java apps, you might split out the functionality into separate JARs, again each of these could be a sub-module under the overall project and again you can build them independently, run separate goals/phases/reports etc.