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From: Martin Gainty <mgainty@hotmail.com>
To: "users@maven.apache.org" <users@maven.apache.org>
Subject: RE: Topologically sorted list of Artifacts for use by a plugin?
Date: Sun, 5 Jan 2014 18:24:56 -0500
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> Date: Sat=2C 4 Jan 2014 16:11:02 -0800
> Subject: Re: Topologically sorted list of Artifacts for use by a plugin?
> From: ljnelson@gmail.com
> To: users@maven.apache.org
>=20
> On Fri=2C Jan 3=2C 2014 at 6:17 PM=2C Martin Gainty <mgainty@hotmail.com>=
 wrote:
>=20
> > MG>so I would say you are definitely on the right track
> >
>=20
> Thanks=3B I'm not sure I am.
>=20
>=20
> > MG>any reason for topological sorting of dependencies?
> >
>=20
> In my original post=2C I wrote:
>=20
> (As background: I am working with Liquibase (http://www.liquibase.org/).
> > Each of my .jar projects has a META-INF/liquibase/changelog.xml file in
> > it. Various of these .jar projects already depend on each other--for un=
it
> > and integration testing=2C I'd like to use this dependency order=2C har=
vest the
> > changelog.xml resources in each .jar file=2C and then combine them to c=
reate
> > only the database tables actually needed for the test. If a.jar has A's
> > tables=2C and b.jar has B's tables and b.jar depends on a.jar=2C then I=
'd like
> > to run a.jar!/META-INF/liquibase/changelog.xml first=2C then
> > b.jar!/META-INF/liquibase/changelog.xml next=2C and I'd like to not hav=
e to
> > specify this in any place in my pom.xmls=2C since the dependency order =
is
> > already captured there.)
>=20
>=20
> So the fact that I'm using
> ProjectSorter<http://maven.apache.org/ref/3.0.5/maven-core/apidocs/org/ap=
ache/maven/project/ProjectSorter.html>strikes
> me as wrong=97worse than wrong: an awful hack=2C in fact=97because I am
> basically using the reactor to sort MavenProjects that I've roped in from
> elsewhere. Yucko.
>=20
> Various people have noted tersely that the maven-dependency-plugin is wha=
t
> I want. Of course=2C its *goals* are completely useless for this task
MG_01_05>I went the same tack but I couldnt find a goal to collect all the =
dependencies so I deprecated that thought process

=20

>=97but
> buried in an obscure StackOverflow comment tangentially related to the
> maven-dependency-plugin I found a reference to this class:
> http://maven.apache.org/shared/maven-dependency-tree/apidocs/index.html?o=
rg/apache/maven/shared/dependency/graph/DependencyGraphBuilder.html
> If I understand it right=2C then code like the following should do the
> trick
> (untested=2C but you get the general idea):
>=20
> public class Artifacts {
>=20
> private final DependencyGraphBuilder dependencyGraphBuilder=3B
>=20
> public Artifacts(final DependencyGraphBuilder dependencyGraphBuilder) {
> super()=3B
> this.dependencyGraphBuilder =3D dependencyGraphBuilder=3B
> }
>=20
> public Collection<? extends Artifact>
> getDependencyArtifactsInTopologicalOrder(final MavenProject project) thro=
ws
> DependencyGraphBuilderException {
> List<Artifact> returnValue =3D null=3B
> final DependencyNode projectNode =3D
> this.dependencyGraphBuilder.buildDependencyGraph(project=2C null /* no
> ArtifactFilter=3B prob. need one */)=3B
> assert projectNode !=3D null=3B
> final CollectingDependencyNodeVisitor visitor =3D new
> CollectingDependencyNodeVisitor()=3B
> projectNode.accept(visitor)=3B
> final Collection<? extends DependencyNode> nodes =3D visitor.getNodes()=
=3B
> if (nodes !=3D null && !nodes.isEmpty()) {
> returnValue =3D new ArrayList<Artifact>()=3B
> for (final DependencyNode node : nodes) {
> if (node !=3D null) {
> final Artifact artifact =3D node.getArtifact()=3B
> if (artifact !=3D null) {
> returnValue.add(artifact)=3B
> }
> }
> }
> if (!returnValue.isEmpty()) {
> Collections.reverse(returnValue)=3B
> }
> }
> return returnValue=3B
> }
>=20
> }
MG_01_05>An excellent test-case for maven-dependency-tree
>=20
> I think that might be the right way to do it. It's unclear to me how
> Maven's internals themselves make use of this class=2C but it is probably
> used somewhere=2C and it clearly hides and mediates between the Sonatype
> Aether and
MG_01_05>most of the Original Sonatype authors monitor this list..

> Eclipse Aether kerfuffle that occurred between 3.0.5 and 3.1.x=2C
MG_01_05>a fair amount of confusion once IBM orphaned Eclipse to OpenSource=
 mavens
MG_01_05>The one 'positive' we 'gain' is seamless integration to Eclipse ID=
E..

> so this also seems like something that isn't going to be deprecated any
> time soon.
MG_01_05>lets hope..!

> IWBNI there were a quick primer in the documentation somewhere about how
> Maven loads its own guts. I know that fundamentally Maven is just a bundl=
e
> of components that get instantiated and wired together by Plexus but it
> sure is confusing to try to figure out how and where something is called=
=97as
> a result when there are problems you have to go digging through=2C well=
=2C
> obscure StackOverflow questions. :-)
MG_01_05>usually if we can funnel the permutations of thought processes to =
one specific question an answer will be MG_01_05>shortly forthcoming for a =
real adventure in managing maven repositories thru Embedding I invite you t=
o take ride on MG_01_05>the Aether train

MG_01_05>http://blog.sonatype.com/2010/08/introducing-aether/
> Best=2C
> Laird
MG_01_05>Thanks for taking time to 'think this through'
MG_01_05>All the Best=2C Martin-
>=20
> --=20
> http://about.me/lairdnelson

 		 	   		  =

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