[jboss-dev] Why Maven sucks (part 1)

[Adrian Brock]

On Mon, 2008-04-21 at 13:47 -0500, Paul Gier wrote:
> Carlo de Wolf wrote:
> > Paul Gier wrote:
> >> Carlo de Wolf wrote:
> >>
> >>>
> >>> Now if it was a tool focussed on dependency management (like Ivy) it 
> >>> would have solved the real problem: snapshots. So let's do an example:
> >>> - as trunk -> ejb3-core-0.1-SNAPSHOT -> 
> >>> ejb3-interceptors-0.13-0-SNAPSHOT -> aop-2.1-SNAPSHOT (for the example)
> >>> If I happen to deploy a new snapshot of aop, it'll break AS build. 
> >>> Why: ejb3-core is not compatible and Maven blindly loads it up. This 
> >>> is not possible in Ivy, it's snapshot repository looks like:
> >>> - as trunk -> ejb3-core-0.1-20080421 -> 
> >>> ejb3-interceptors-0.13.0-20080421 -> aop-2.1-20080420.
> >>> If I happen to deploy a new snapshot of aop you get and I run a 
> >>> nightly build on ejb3 you get:
> >>> - as trunk -> ejb3-core-0.1-20080421 -> 
> >>> ejb3-interceptors-0.13.0-20080421 -> aop-2.1-20080420
> >>> - ejb3-interceptors-0.13-0-20080422 -> aop-2.1-20080422
> >>> Since ejb3-core didn't properly build there is no new snapshot for it 
> >>> and AS build is unaffected.
> >>> Combine this with unit tests and you got a pretty stable setup.
> >>>
> >>
> >> We can do this using maven also.  If you want to tie the build to a 
> >> specific snapshot, just put the full snapshot version in the 
> >> dependency.  So for example, ejb3-interceptors you could put version 
> >> "0.13.0-20080417.210958-18".  And maven will keep using that snapshot 
> >> build until you change the dependency.  The -SNAPSHOT convention is 
> >> just for convenience if you just want to build with the latest until a 
> >> release comes out.
> > 
> > It must be automated. Whenever someone does a mvn deploy, the pom.xml 
> > should be replaced by one not containing any snapshots, but only full 
> > versions.
> > 
> 
> Just so it's clear what you are asking for, you want dependencies with 
> (-SNAPSHOT) to be replaced with the specific snapshot version (-timstamp-build) 
> during deployment?  I could probably add this as an option to the deploy plugin, 
> but I don't know if this would solve the problem.
> 

It wouldn't. The whole point of getting rid of snapshots is so you can
reproduce the build with a tagged release.

People need to stop being lazy and create proper releases.

SNAPSHOTS are only useful when you want to know whether a new release
will work another project.

e.g. before I release the next version of jboss-vfs, I create a SNAPSHOT
in my *local* repository and update the jbossas build to use it.
If it works, I do a proper release (NOT a mvn deploy of the SNAPSHOT)
for others to use.

> Just as an example, let's say you deploy an ejb3 module that has a dependency on 
> jboss-aop.  You deploy and it resolves to aop snapshot build 9.  The app server 
> has a dependency on the current aop snapshot (2.0-SNAPSHOT) and they both point 
> to build 9 so all is fine.  Then aop deploys a new snapshot (build number 10). 
> The app server depends on aop (-SNAPSHOT) so it gets the new version.  Now the 
> app server wants build 10, but ejb3 wants snapshot version 9.  The app server 
> IMO should win because the direct dependency should take priority over the 
> transitive ejb dependency.  To solve this issue you would still have to change 
> the app server dependency to tie it to the specific snapshot of aop.
> 
> 
> 
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Adrian Brock
Chief Scientist
JBoss, a division of Red Hat
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