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From "Liu, Raymond" <>
Subject RE: How to resolve right dependency which enabled and built/install with profile?
Date Thu, 12 Dec 2013 01:56:53 GMT
Actually, I think it is possible, though probably could not be done by current Maven implementation.
As long as B can know which libjar the shim A is built upon. I am saying that it is possible
is because that I can achieve the goal with SBT, when sbt do publish local, it will fill the
profile info ( actually not profile in sbt, but some compile time config ) into A's final
pom, then when assemble B, the installed A actually do not have any profile info in A's pom.
B then assemble with the right libjar which A is built upon.

Best Regards,
Raymond Liu

-----Original Message-----
From: Stephen Connolly [] 
Sent: Wednesday, December 11, 2013 6:47 PM
To: Maven Users List
Subject: Re: How to resolve right dependency which enabled and built/install with profile?

You are looking for the impossible.

You want A to work with any version of libjar

You want B to use A but not know which version of libjar the A it is using depends on... actually
to be independent of the version of libjar that A depends on... but also to bundle the specific

Rethink what you are asking and you will see that you are asking an impossible request...
you are asking somebody to hop on one leg and mandating that the one leg be both their left
and right leg.

When you are asking an impossibility, that is usually a sign that you are going at things
the wrong way.

If A is going to become part of a fatjar at some point, you need to make a decision *at the
point of creating the fatjar* as to which libjar will be included within A.

Or else perhaps, you include all versions of libjar and provide a means for A to decide which
version it wants... there are many ways to achieve this...

* use the service provider pattern to introduce another shim layer and then use the shade
plugin to put all the shim impl libjar deps into independent package namespaces
* use a custom classloader and package libjar as resources, so that A's entry point loads
the correct libjar at runtime
* etc.

With the above you would be including *all* versions of libjar within A and the whole thing
becomes moot anyway...


On 11 December 2013 00:52, Liu, Raymond <> wrote:

> Thanks Stephen
>         I see your solution is let B manage the libjar version. While 
> this is against my wish, I wish B to know nothing about A's internal 
> implementation. In the future, A might depends on a v3.0 libjar, I do 
> wish to just repackage B to make it work not revise B's code or assembly rules.
> And sometime A might be buried deep in the dependent tree, Those 
> project might not even aware it depends on A, they just wish it works 
> on whatever current A's binary jar, which then need the right libjar 
> dependency when assembly.
>         And I know it seems hard to use profiles to manipulate 
> dependencies. While by theory, I think this is a reasonable 
> requirement that a project do not need to take care of its 
> dependencies' internal implementation of what it depends on, It just 
> wish it works. E.g. if the POM file is installed in a way that when it 
> build with profile, the corresponding dependencies and any other 
> modifying is fill in the final POM file. ( since the profile is not 
> used anyway when resolve dependencies, why keep it there? For source 
> jar? ) Then those project depend on it won't worry about A's profile, 
> it's already the correct one which been used on building A with this installed or downloaded
binary jar.
>         So , using profile might not be the right solution, While if 
> there isn't an automatic way to meet this requirement, can I take it 
> as a feature missing?
> Best Regards,
> Raymond Liu
> -----Original Message-----
> From: Stephen Connolly []
> Sent: Tuesday, December 10, 2013 6:57 PM
> To: Maven Users List
> Subject: Re: How to resolve right dependency which enabled and 
> built/install with profile?
> Using profiles to manipulate dependencies is a route to madness.
> An modules dependencies should be a constant... It was a mistake to 
> allow <dependencies> within <profile>.
> The correct solution is to create additional modules that aggregate in 
> the corresponding lib versions (this is also a bad plan, but less 
> worse than your current plan by quite some margin). The additional 
> modules would depend on A and the respective version of libjar and 
> bundle the two together.
> Then B can depend if the corresponding internmediate... Now at this 
> point you will start to see the madness returning... That is if you 
> need two versions of B.
> The better solution is to just let B depend in A and then do the 
> fatjar as the final later after B and *override* the transitive dep on 
> libjar in the two fatjar building modules
> On Tuesday, 10 December 2013, Liu, Raymond wrote:
> > Hi
> >
> > I have a project with module A that will be built with or without 
> > profile say -Pnewlib , thus I can have it build with different 
> > version of library dependency let's say by default use libjar-1.0 
> > and when -Pnewlib will use libjar-2.0.
> >
> > Then, I have a module B to depends on module A. The issue is that 
> > how can I get the right dependency in module B for libjar? I want to 
> > assemble a fat jar so I need to figure out which version of libjar 
> > to
> include.
> >
> > In my test, it seems to me that when mvn -Pnewlib install module A, 
> > though it will build with libjar-2.0. but the installed pom do not
> reflect this.
> > Thus when module B resolve the dependency, it will resolve the 
> > dependency as libjar-1.0 ( though when building module B, -Pnewlib 
> > is also passed in, But I think this will not pass to the dependent 
> > package when resolve the dependency).
> >
> > I don't want to have module B know anything about the libjar-1.0 and 
> > libjar-2.0. it should handle by module A, and module B just simply 
> > call into module A.
> >
> > Actually, I think this apply the same if A and B are not modules in 
> > one project, but standalone projects. In which case B will not 
> > define profile at all.
> >
> > So how can I achieve this goal? say, A take care of lib dependency 
> > when build and install. B who depends on A, when assembly can 
> > retrive the right lib dependency.
> >
> > Best Regards,
> > Raymond Liu
> >
> >
> >
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