$Revision: 1.6 $	$Name: $	$Date: 2006/04/13 13:54:09 $	Working with maven 2
$Source: /ppw/training/maven/repository/maven2/src/html/callingPlugins.html,v $

Calling Plugins

All work in maven is done by plugins
- E.g., maven-javadoc-plugin
A plugin is a jar, classified the maven way
- groupId, artifactId, version
- E.g.,
  - <groupId>org.apache.maven.plugins</groupId>
  - <artifactId>maven-javadoc-plugin</artifactId>
  - <version>2.0-beta-2</version>
- A plugin is a collection of Mojo's
- Carries a descriptive XML file
  - unzip the jar and have a look
- There is no default Mojo in a plugin :-(
A Mojo is 1 class with an execute method
- void execute() throws org.apache.maven.plugin.MojoExecutionException
- Arguments and options are properties
- Class is instantiated using IoC as Plexus component
  - Arguments and options are set by the framework from the POM
- Each Mojo works in total isolation (separate ClassLoader)
- E.g., org.apache.maven.plugin.javadoc.JavadocReport
Mojo == goal
- Defined via annotations
- E.g., @goal javadoc

Calling a Plugin

mvn groupId:artifactId:[version:]goal
E.g., mvn org.apache.maven.plugins:maven-javadoc-plugin:2.0-beta-2:javadoc
Creates target/javadoc
Without the version, we use the latest version of the plugin
- E.g., mvn org.apache.maven.plugins:maven-javadoc-plugin:javadoc

Plugin Prefix

To make typing commands easier: mvn prefix:goal
artifactId == maven-${prefix}-plugin
- E.g., javadoc resolves to maven-javadoc-plugin
Or specifically set a <goalPrefix /> in pom.xml of the plugin
- Must be unique in group
groupId: we look in configured pluginGroups
- Set in $M2_HOME/conf/settings.xml or ~/.m2/settings.xml
```
[…]
  <pluginGroups>
    <pluginGroup>groupId</pluginGroup>
  </pluginGroups>
[…]
```
Default plugin groups are always used:
- org.apache.maven.plugins
- org.codehaus.mojo
E.g., mvn javadoc:javadoc

Binding a Plugin Goal to a Build Lifecycle Phase

The standard build lifecycle has abstract phases

Plugin goals can be bound to such a phase

Add to the pom.xml

<project […]
[…]
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-javadoc-plugin</artifactId>
       [<version>2.0-beta-2</version>]
        <executions>
          <execution>
            <phase>process-classes</phase>
            <goals>
              <goal>javadoc</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
[…]
</project>

Add an execution of goal javadoc of plugin org.apache.maven.plugins:maven-javadoc-plugin[:2.0-beta-2] to the build lifecycle phase process-classes
mvn package
- Will now also execute javadoc:javadoc
- During the process-classes phase

Standard Build Lifecycle Phase Bindings

There are standard bindings via the <packaging />-element in pom.xml
Call using a build lifecycle phase
- mvn phase
- E.g., mvn post-clean