You are here

Home › Articles

Maven 2

Here is a list of issues and solutions

Setting and using internal repository

Our internal repository is located at Linux box with https and ssh access

Contents of settings.xml

<servers>
<server>
<id>devlab-ssh</id>
<username>root</username>
<password>password</password>
<configuration>
	<sshExecutable>D:\Progra~1\Utils\Putty\plink</sshExecutable>
	<scpExecutable>D:\Progra~1\Utils\Putty\pscp</scpExecutable>
	<sshArgs>-P 2222</sshArgs>
	<scpArgs>-P 2222</scpArgs>
</configuration>
</server>
</servers>

If you do not specify password, Maven will ask for it. - I have to investigate this further, because it doesn't work for me.

If you use non standard port (port 2222 in this case) or need another switches, use sshArgs and scpArgs.

If you have plink and pscp on your PATH, you do not need to specify full path. If you specify path, don't use spaces.

The plink is apparently used to create directory structure in your repository, pscp can only copy files.

Test the access with pscp

It is a good idea to test if you can upload files with pscp from command line.

Deploy a file

mvn deploy:deploy-file
-Durl=scpexe://yourhost.com/path/to/maven2/repository
-DrepositoryId=devlab-ssh
-DgroupId=javax.j2ee
-DartifactId=javaee
-Dversion=5.0.FCS
-Dpackaging=jar
-Dfile=e:/temp/javaee-5.0.FCS.jar

The repositoryId is matched against server/id section in settings.

Resources

Remove artefacts from repository

Apparently there is no support for removing artefacts from repository. The fix is scheduled for Maven 2.2.

How to clean local repository

(by Brett Porter) I think the best way to clean in this case is to move your repository to a new location, and add the file:// location to your list of remotes. Once all your projects are building, your "local" one is clean so you can remove the old one.

Patching plugins

Patched plugins with -INTERNAL are considered as normal artefacts, only artefacts with -SNAPSHOT are "snapshots". It means that -INTERNAL are downloaded from pluginRepositories.pluginRepository.releases and not from pluginRepositories.pluginRepository.snapshots and so on.

When the patched plugin is deployed to internal reposity as -INTERNAL, the POM is not downloaded from the repository, so the plugin doesn't work. So I decided to deploy SNAPSHOTS to internal repository. It means, that there is no need to change plugin version, jsut keep the -SNAPSHOT. Also the distributionManagement.repository must be chagned to distributionManagement.snapshotRepository so it will override any settings from parent POM.

The SNAPSHOTS from internal repository should not interfere with snapshots from central repository, because super POM default settings ignores SNAPSHOTS in central repository.

It's strange that -INTERNAL was chosen, because for example 1.2-SNAPSHOT is newer than 1.2-INTERNAL, see version comparison.

xmlbeans-maven-plugin 2.0 and XMLBeans 2.2

The xmlbeans-maven-plugin 2.0 depends on XMLBeans 2.0 and there seems to be no way how to use newer version. The plugin needs to be patched, see JIRA issue, some patch was already posted.

Get the xmlbeans-maven-plugin sources from SVN, change the dependency in POM to xbean-2.2, build with mvn install. Follow the Patching Maven Plugins - copy pom.xml to pom-internal.xml, version to -INTERNAL, modify the distributionManagement and deploy to internal repository with mvn -f pom-internal.xml deploy.

maven-ejb-plugin and EJB3

The maven-ejb-plugin v2.0 doesn't support EJB3 (requires ejb-jar.xml). The 2.1-SNAPSHOT should support EJB3 but is not yet released. Download it from SVN and deploy it similar to xmlbeans-maven-plugin.

xdoclet-maven-plugin and Java 5 annotations

The xdoclet-maven-plugin 1.0-alpha-2 doesn't work well with Java 5 annotations. The problem is in xjavadoc parser, see JIRA issue. Use xjavadoc-1.1-j5-v4.jar.

The xdoclet-maven-plugin 1.0-beta-1 supports properties where one can specify version of xjavadoc to use. Unfortunately, beta-1 is not published. Download it from SVN, and deploy it similar to xmlbeans-maven-plugin.

Command line options

I did not found a page with Maven 2 command line options. The command line options can be obtained with:
mvn --help.
Here is output for maven 2.0.4: 

usage: mvn [options] [<goal(s)>] [<phase(s)>]

Options:
-C,--strict-checksums         Fail the build if checksums don't match
-c,--lax-checksums            Warn if checksums don't match
-P,--activate-profiles        Comma-delimited list of profiles to
                           activate
-ff,--fail-fast               Stop at first failure in reactorized builds
-fae,--fail-at-end            Only fail the build afterwards; allow all
                           non-impacted builds to continue
-B,--batch-mode               Run in non-interactive (batch) mode
-fn,--fail-never              NEVER fail the build, regardless of project
                           result
-up,--update-plugins          Synonym for cpu
-N,--non-recursive            Do not recurse into sub-projects
-npr,--no-plugin-registry     Don't use ~/.m2/plugin-registry.xml for
                           plugin versions
-U,--update-snapshots         Update all snapshots regardless of
                           repository policies
-cpu,--check-plugin-updates   Force upToDate check for any relevant
                           registered plugins
-npu,--no-plugin-updates      Suppress upToDate check for any relevant
                           registered plugins
-D,--define                   Define a system property
-X,--debug                    Produce execution debug output
-e,--errors                   Produce execution error messages
-f,--file                     Force the use of an alternate POM file.
-h,--help                     Display help information
-o,--offline                  Work offline
-r,--reactor                  Execute goals for project found in the
                           reactor
-s,--settings                 Alternate path for the user settings file
-v,--version                  Display version information

Artifact version comparison

The Better Bbuilds with Maven, page 61, first paragraph is unclear about version comparison: "A version that contains a qualifier is always considered newer than a version without a qualifier; for example, 1.2 is newer than 1.2-beta". Unfortunately this is in contradiction.

The version parser and comparator can be found in org.apache.maven.artifact.versioning.DefaultArtifactVersion, that is part of maven-artifact.jar. From the file I can read:

  • qualifier is always parsed as string
  • qualifier and build number are mutually exclusive
  • missing major, minor or build number are considered to be zero (0)
  • version without qualifier is newer than version with qualifier
  • qualifiers are compared as strings, when qualifier1.compareTo(qualifier2) , it means that qualifier2 is newer (-SNAPSHOT is thus newer than -INTERNAL). When the strings are same except ending, the shorter is considered newer.

Useful Mojos and switches

  • Plugin configuration options: 
    mvn help:describe
-DgroupId=org.apache.maven.plugins
-DartifactId=maven-compiler-plugin
-Dfull=true
  • Show effective POM: 
    mvn help:effective-pom
  • Show effective settings: 
    mvn help:effective-settings
  • Show artifact dependencies: 
    mvn -X package