Parameterise a Maven Multimodule Build

Question

I'm looking for a possibility to parameterise a multi-module build in a way that I can replace/specify some files (eg UML files) that are used during the build in order to produce different output. The procedure of the build stays the same but I want to be able to produce different output depending on the input UML model.

I have a multi-module project that builds several jars based upon an UML model. The pom structure looks as follows:

+ generation
  - mod1
  - mod2
  - mod3

The root pom (generation) generates java sourcecode (.java) based upon an UML model stored in the directory /uml. Afterwards the modules (mod1...3) compile distinct subsets of this sourcecode and package the output as jar.

I want to reuse this build procedure and apply it to different UML models. How can I reuse the entire generation, compilation and packaging procedure defined in the multimodule project in other maven projects?

# Generate jars based upon the foo UML model
+ generation-foo
  /uml/foo.uml

# Generate jars based upon the bar UML model
+ generation-bar
  /uml/bar.uml

Update
I could use profiles in the generation project in order to define the different input uml models and then just activate the relevant one. But I would lose traceability that way.

Perhaps a completely new approach would be a better idea ... any suggestions?

Answer 1

Conceptually, I would say, Maven is designed around the POM file which is a model of the project that is being built. It is not so much a process description that applies a function to an input and results in an output on basis of that.

That being said, there is a lot possible with properties in the POM, which then can be passed along on the command-line: -Dproperty=value . It looks as if you would be able to pass the property to whatever process is generating the source code.

I may express some caution, though. I'm seeing some possible red flags in the overall design that you describe. If modules (regardless of their inheritance relationship) pass along files/folders, that should preferably go through install ation. So, if you were to do that, you end up with a version of the parent project in your local repository of which you don't really know what it is. Which parameters were used? And how will a user of that artifact then deal with that?

I'm not saying this won't work, but it may get hairy and not play entirely well within more traditional Maven implementations.

Answer 2

I'm not entirely sure I understand your use cases but you might want to look at:

• POM Inheritance : Defining as much as you can in the parent module (different groups of modules can have the same parent)
• Maven profiles : you can activate based on all sort of potential conventions like even the project name.
• Maven Archetypes : And finally I think based on what your saying this maybe the only solution of a reusable project template