Maven 2 is Still Alive : Even after setting Maven3 - maven

And i got a requirement, converting a Maven 2 project to Maven 3. So i downloaded Maven 3.2.1 and edited the Maven path to 3.And also changed Maven installation in eclipse to point Maven 3.
But when i run my project in eclipse, it is still taking maven 2 plugins. Could you please help me with this ?

Versions are just versions, there's no real relation between the Maven version and the plugin version. Actually, the Maven team tried to keep the maven-plugins as much as possible compatible with Maven3.
https://cwiki.apache.org/confluence/display/MAVEN/Maven+3.x+Plugin+Compatibility+Matrix shows the list of maven plugins and from which version they can be used with Maven3. Only the Maven-site-plugin required a major release, since it had to adopt the reporting part which has been removed with Maven3.

Related

pom error - org.apache.maven.archiver.MavenArchiver.getManifes

I am getting error in pom file - org.apache.maven.archiver.MavenArchiver.getManifest(org.apache.maven.project.MavenProject, org.apache.maven.archiver.MavenArchiveConfiguration)
in my pom i am using maven-war-plugin 3.0.0 , IDE- STS , java 7
encountered the same issue after updating the maven-jar-plugin to its latest version (at the time of writing), 3.0.2.
Eclipse 4.5.2 started flagging the pom.xml file with the org.apache.maven.archiver.MavenArchiver.getManifest error and a Maven > Update Project.. would not fix it.
Easy solution: downgrade to 2.6 version
Indeed a possible solution is to get back to version 2.6, a further update of the project would then remove any error. However, that's not the ideal scenario and a better solution is possible: update the m2e extensions (Eclipse Maven integration).
Better solution: update Eclipse m2e extensions
From Help > Install New Software.., add a new repository (via the Add.. option), pointing to any of the following URLs:
https://otto.takari.io/content/sites/m2e.extras/m2eclipse-mavenarchiver/0.17.2/N/LATEST/ or
http://repo1.maven.org/maven2/.m2e/connectors/m2eclipse-mavenarchiver/0.17.2/N/LATEST/
Then follow the update wizard as usual. Eclipse would then require a restart. Afterwards, a further Update Project.. on the concerned Maven project would remove any error and your Maven build could then enjoy the benefit of the latest maven-jar-plugin version.
Additonal notes
The reason for this issue is that from version 3.0.0 on, the concerned component, the maven-archiver and the related plexus-archiver has been upgraded to newer versions, breaking internal usages (via reflections) of the m2e integration in Eclipse. The only solution is then to properly update Eclipse, as described above.
Also note: while Eclipse would initially report errors, the Maven build (e.g. from command line) would keep on working perfectly, this issue is only related to the Eclipse-Maven integration, that is, to the IDE.
Upgrade your m2e extensions instead downgrade.
(In Eclipse IDE) From Help > Install New Software.., add a new repository (via the Add.. option)
Specify name for your plugin and add path http://repo1.maven.org/maven2/.m2e/connectors/m2eclipse-mavenarchiver/0.17.2/N/LATEST/
once you are done with installation, please restart eclipse and update your project.

How does Maven decide what version of a plugin to use, when you don't specify any?

I recognized that Maven not always uses the latest version of a plugin.
For example org.codehaus.mojo:sonar-maven-plugin version 2.7 has beed released on 19th of October but on 23th of October, 2.6 was still used by Maven (mvn sonar:sonar).
I even remember some plugins, where the latest version was several minor releases above the version that Maven decided to use.
Is there any (central) index/list/database where Maven looks up what version to use? If yes, where can it be accessed manually?
I know this is an ancient thread but in the interest of posterity and accuracy: all pom.xmls logically inherit from the super POM. You can always see what your "real" pom.xml looks like by typing:
mvn help:effective-pom
The resulting pom.xml that is printed is a combination of the super POM, your pom.xml, and of course any parent POMs in the mix as well.
The super POM is provided by the org.apache.maven.model.superpom.DefaultSuperPomProvider class (https://github.com/apache/maven/blob/bce33aa2662a51d18cb00347cf2fb174dc195fb1/maven-model-builder/src/main/java/org/apache/maven/model/superpom/DefaultSuperPomProvider.java#L56-L85). The resource it loads is org/apache/maven/model/pom-4.0.0.xml (https://github.com/apache/maven/blob/bce33aa2662a51d18cb00347cf2fb174dc195fb1/maven-model-builder/src/main/resources/org/apache/maven/model/pom-4.0.0.xml#L23-L149).
As far as i know, this link will answer your question.
Automatic Plugin Version Resolution
When a plugin was invoked without an explicit version given in the POM
or on the command line, Maven 2.x used to pick the latest version
available where the latest version could either be a release or a
snapshot. For the sake of stability, Maven 3.x prefers the latest
release version over the latest snapshot version.
Given the threat of non-reproducible builds imposed by automatic
plugin version resolution, this feature is scheduled for removal as
far as plugin declarations in the POM are concerned. Users of Maven
3.x will find it output a warning when missing plugin versions are detected to encourage the addition of plugin versions to the POM or
one of its parent POMs. The Enforcer rule requirePluginVersions can be
used additionally check for missing plugin versions in the POM
For command line execution if a version is not specified Maven looks up the latest version from the GA (group ID/artifact ID) maven-metadata.xml file.
Example: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-clean-plugin/maven-metadata.xml
If you're encoding command line execution of Maven goals into your builds you should specify a version for these, otherwise your builds may change as new versions of plugins are released.

what is dependency for Sonar-plugins in POM

We have upgraded SonarQube from version 3.7.2 to 4.5.5. We are using maven to
build and deployment.
There are some plugins need to be updated. But, I am not sure whether, I am not able to find the exact GAV parameter for them or to find latest version using POM.
e.g Build-stability-plugin; I am not able to find version 1.3 for this plugin on maven repository.
Any kind of help will be appreciated
You mix Maven plugins and SonarQube plugins. The latter doesn't need to be deployed in Maven repository nor to be defined in project poms.

Cannot get the latest version of maven plugin

I am new to maven, I have write my own maven plugin with the pom file
<groupId>com.xxx.api</groupId>
<artifactId>xxx-maven-plugin</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>maven-plugin</packaging>
then, in my IDE (intellij) I used clean install to install my maven plugin
and in the main project, my maven plugin works fine.
However, when I modify my maven plugin by adding parameter to my mojo and "mvn clean install" ,
(the groupId,artifactId,version keep the same) it supposed to be the latest version.
However, in the main project, when I try to use the latest maven plugin, I always get the old version
i.e I cannot configure the parameter that I just add to my maven plugin (because it is not exist!)
I have try to delete the maven plugin in my .m2 repo, before I install the latest version of my maven plugin, it still not work.
Any solution that I can get the latest version of my maven plugin by keeping the same
(groupId, artifactId,version)?
thanks,
Zach
Check how the using project is configured. I guess it has its own lib/classes folder. I would suspect that your project has a copy of the older version of the plugin in its lib folder. If so, that is where it is getting the old version. Clean it out from there, i.e. you need to clean the using project.

Maven install:? - how to create a release candidate?

Is it possible to create a release candidate from my current maven project without changing the version number in the pom.xml?
I just want to build a new maven artifact form my project with a specific version number.
For example: my current pom.xml has the version '0.0.1'. I have called mvn install to create the artifact in my local repository. Now I would like to create a second artifact with the version '0.0.1-RC1'
Is this possible from the mvn command line without changing the version number in my pom.xml?
I would advice against your suggestion of not changing the version number. One of the Maven's benefits is to keep your releases in sequence, i.e. after you have made your '0.0.1-RC1' candidate you will continue to work on the '0.0.1-RC2-SNAPSHOT' version (which may result in a '0.0.1-RELEASE').
That said, you don't have to change the version number manually. The Maven Release Plugin offers great help with this with commands such as mvn release:prepare and mvn release:perform. Also read the Maven build versions in the Maven reference manual. You may also find the discussion about Maven version scheme interesting.
As I see it you have two options:
Embrace the release plug-in. It's been designed to address this problem.
Use the versions plug-in and issue your own source code control commands.

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