Let's take a step back and look at the deployment artifacts of our enterprise application. Typically, an application results in a single artifact that will run our software. Even with several multi-modules being used at the end of the day, these will boil down to a single or few artifacts. So, in most of the cases all of this structure is flattened again into single JAR or WAR files. Looking at the reusability of modules, which is not necessarily being given, this raises the question of whether we need several modules per project at all. At the end of the day, introducing and managing sub-projects, vertical or horizontal, will require certain developer effort.

It is true that splitting up the code base can improve build performance if only sub-projects that have been changed are rebuilt. However, in the sub-chapters Apache Maven and Gradle and Chapter 4, Lightweight Java EE we will see that building a single reasonably designed project into a single artifact is sufficiently fast and that there are usually other aspects responsible for making builds slow.