[mojo] How to execute logic once for several projects..

[Jeroen Leenarts <je...@gmail.com>]

Hi,

I have the following usecase:

"Run a mojo to collect generated reports from all other modules and combine
these into one big report."

This involves collecting a number of XML files which will be combined into
one file, but that's not the problem. Just a matter of retrieving output
directories by means of the expression ${reactorProjects}.

The problem is how to influence the actual moment of execution of a MOJO.

I've got a couple of approaches that might work, but each of them pose some
kind of problem.

Here are my ideas:
-Execute a mojo on all modules, monitor the build order and when the last
project being built is active, run my reporting.
   PROBLEM: How to detect which project is the last project being built?

-Execute a mojo only on the multi-project pom which uses the @aggregate
annotation.
   PROBLEM: The @aggregate does not seem to force a mojo to be ran once. The
mojo is inherited to a child POM and gets executed. (I have a small demo
running demonstrating this behaviour.)
   PROBLEM: How to force the execution of the parent POM to be last? In my
mind this is impossible to achieve when using parent-child relations between
multimodule projects and individual modules due to ordering imposed by
inheritance.

-Configure an extra project, depending on all other projects, which will
force this project to be executed last and configure my collecting MOJO on
that.
   PROBLEM: This seems fragile to me because it is important to update this
pom everytime anything changes.

Any ideas about what I could do? If my usecase isn't entirely clear, please
let me know. I'll try to elaborate.

Regards,
Jeroen