Howdy, The story of BOM POMs is manifold. BOM POMs are a "very good thing" to publish for _downstream consumers_ that consume your stack. Problems begin when devs try to "reuse" the BOM within their own build (same reactor BOM is published from).
If consuming BOM, it should ideally come from outside (external to) your reactor. If you use "import" scope within the reactor, it is where (does not have to, IF you are VERY careful) problems begin. Moreover, you usually want to "detach" the BOM from your parent POM, that even more introduce peculiarities and problems (ie. how to deploy it? So you now introduce some "skinny" parent, etc) Hence, the general rule of thumb is: - BOM is good per se - BOMs you consume should _always_ originate from outside of the reactor (simply to avoid all the problems). - BOMs you produce should target downstream consumers ONLY Moreover, Maven 4 has a capability now (not in Maven3!) to _import BOM with classifier_. Hence, with Maven4 (obviously, this makes build maven4 only), the preferred way to do things is: - sort out dependencies in reactor "as usual", using INHERITANCE - do NOT re-import BOM within reactor - BOM you author/publish should be used ONLY by downstream projects - generate your BOM As an example, you can look at Maven build itself: - it generates BOM - offers two BOMs: skinny and fat And here comes the second important bit: there is a disagreement (or different interpretation) about "what BOM is". Hence, Maven itself delivers TWO BOMs: skinny and fat. See [1] for explaining what "skinny" and "fat" BOMs are. [1] https://github.com/apache/maven-site/pull/598#discussion_r1894013277 HTH T On Sat, Jan 25, 2025 at 1:50 AM Olivier Lamy <ol...@apache.org> wrote: > > Hi, > Nice presentation. > I have been asking on slack but no answer, so I still don't understand why > this > " Warning: Same-reactor BOMs will be deprecated (use external BOMs only!` ?" > > It's very convenient for large projects providing boms to have > demos/examples as part of their build. > And obviously, those demos/examples use the bombs to show good usage > (in my case, the Jetty project). > So why is it such a problem? > > On Thu, 23 Jan 2025 at 01:25, Tamás Cservenák <ta...@cservenak.net> wrote: > > > > Howdy, > > > > Lately, we get this question quite often. > > > > Today Guillaume assembled this very informative presentation: > > https://gnodet.github.io/maven4-presentation/ > > > > There is also ongoing effort to assemble a page on Maven site as well: > > https://github.com/apache/maven-site/pull/598 > > > > Have fun > > T > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org > > For additional commands, e-mail: dev-h...@maven.apache.org > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org > For additional commands, e-mail: dev-h...@maven.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org For additional commands, e-mail: dev-h...@maven.apache.org
