There are three primary variants of how the artifact resolution can
work with respect to repositories where RS is the set of remote
repositories that will be used for artifact resolution:
1) RS is what's available in the effective POM. Easy.
2) RS is collect from inspecting metadata transitively and reconciling
the repositories found as a set before artifact resolution. Difficult.
3) RS is collection of partitions of sub-trees where the individual
repositories are found. The reconciliation process becomes a
backchaining mediation. Extremely difficult.
1) Pretty simple, and works with repository managers. Most large
organizations will use one within a year. I love this idea from a
Sonatype perspective, but from a Maven user perspective we potentially
cripple OSS projects. What we decide to do here has long lasting
effects. A variation on what Josh Bloch says about APIs. API design
(and corresponding behavior) is like sex. Make one mistake and you
support it for the rest of your life. If we pick this method it will
categorically change the internals of the repository system and it
will make it pretty much impossible to change to 2) or 3) in a
practical way. Based on empirical observations in that aside from
Oleg, Benjamin, Igor, and myself (all Sonatype at the time of
implementation) no one has contributed anything. This is just not
something that can be tinkered with so thinking we can try this method
and then back it out and make it more sophisticated later is a pipe
dream.
I think 2) and 3) require a lot of discussion. So really I think it
boils down to are we going to really make 1) the way it works?
Otherwise I think we are also obliged to look at the models in P2 and
OBR because it probably doesn't make sense to re-invent another
mediation and reconciliation mechanism.
On 2009-10-29, at 12:27 PM, Brian Fox wrote:
It's amazing how google's thread compression of a discussion can cause
me to overlook a huge thread so near and dear to my heart.
To start, Benjamin has hit the nail on the head of a discussion point
Jason and I have had going for quite some time. In fact, we even wrote
up a proposal for it months ago that got little feedback. I've also
blogged on this subject before.
Written and suggested reading in this order:
http://www.sonatype.com/people/2009/02/why-putting-repositories-in-your-poms-is-a-bad-idea/
http://docs.codehaus.org/display/MAVEN/Artifact+resolution+and+repository+discovery
I won't rehash all of what I've already written, and leave it to the
reader to follow the above urls for the majority of the points however
I think there is one key argument that is worth reiterating:
The ability of a user to checkout an open source project with no prior
knowledge of it and simply be able to build it, run the tests and
patch it the first try is the most powerful way to demonstrate the
Maven to new users. Simply removing or ignoring repositories in the
poms will break this functionality that I feel pretty strongly about.
All of the arguments so far in this thread mostly revolve around
issues in corporate / enterprise use, and for these issues repository
managers are the best solution. I don't think its in the best interest
of the community to break OSS use to support Enterprise use,
particularly when that problem is already covered.
Specifically, I'm pretty strongly in favor of continuing to support
repositories declared in poms, however they should be scoped for only
the subtree of dependencies introduced by the pom declaring the repo.
Further, I recognize that having urls burned into immutable poms is
not the best way to accomplish this, and I think we need to find a
better one pretty quickly.
--Brian
On Wed, Oct 28, 2009 at 7:57 PM, Stephen Connolly
<stephen.alan.conno...@gmail.com> wrote:
2009/10/28 Brett Porter <br...@apache.org>
On 29/10/2009, at 2:08 AM, Daniel Kulp wrote:
On Wed October 28 2009 10:53:10 am John Casey wrote:
I tend to agree, they should not really be used. It seems like
these
third-party repositories have a strong potential for causing
network
errors (in cases where the repo is down or on a private
network), and
they definitely push the user in the direction of trusting
anything that
comes from anywhere on the internet without thinking twice...not
a great
idea, and an understandably unpopular one with companies.
I think the role of the <repository> declaration in the POM
should be
shifted in Maven 3. I think this along the same lines that Brett
was
talking, but I'd really like to see them take on an advisory
role rather
than actively participate in resolution. In other words, if an
artifact
cannot be found, then display the list of third-party
repositories which
MIGHT contain the artifact, along with the POM that lists that
repository.
I'm OK with that EXCEPT for repositories defined in the current
pom+parents.
For transitive dependencies, yes, but not for building the current
project.
+1
This avoids fudging with settings.xml, which has other problems
that others
have mentioned, and also because you start building a long list of
repositories then used on *every* project (unless Maven adds some
other gid
restriction on repositories).
+1... though this has the side-effect that if you checkout a
project who's
parent is only in a repository specified in the parent... well hey,
it's not
our fault! ;-)
On 29/10/2009, at 4:22 AM, Dan Rollo wrote:
To advocate the other side: I like the ability to define
repositories in
the pom.xml because team members (oss or corporate) can simply
"get latest"
from the source bank and things work OOTB.
I don't like the idea that the only way for things to work OOTB
is if all
artifacts MUST come from 'central'. There are other open source
repo's in
wide use. Same with private/corporate repos.
Forcing an edit to settings.xml (usually located in the user home
dir) is
also a maintenance issue for automated builds.
Agreed - I think the proposal above gives a balance between the two
concerns.
- Brett
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Thanks,
Jason
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Jason van Zyl
Founder, Apache Maven
http://twitter.com/jvanzyl
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