Maven plugin execution ID

Question

I have a simple question about execution ID in maven plugin.

    <groupId>org.codehaus.mojo</groupId>
    <artifactId>gwt-maven-plugin</artifactId>
    <version>2.7.0</version>
    <executions>
    <execution>
        <id>gwt-process-resources</id>
        <goals>
            <goal>i18n</goal>
            <goal>generateAsync</goal>
        </goals>
    </execution>
</executions>

Can someone explain to me what does this executionId does? How are goals triggered? Can I call directly the "gwt-process-resources" in order to execute both goals? If yes, how can I do that?

Answer 1

<id></id> exists only for you to be able to distinguish between other executions. This tag will be displayed when you do the actual build.

Your execution example will invoke the two goals you have specified: i18n and generateAsync.

If the plugin isn't bound to a specific phase (process-resources, package, install, etc) your execution will not performed. The plugin's documentation should tell if this is the case.

You can specify/override the default phase by using the <phase> tag:

...
<execution>
  <id>gwt-process-resources</id>
  <phase>process-resources</phase> <!-- If you need to override -->
  <goals>
    <goal>i18n</goal>
    <goal>generateAsync</goal>
  </goals>
</execution>
...

...

Goals are either triggered:

• Automatically (implicitly by their default phase or explicitly as above)
• By command line execution: mvn <plugin name>:<goal>

Answer 2

Here is a very simple explanation:

You can not call excecution ids directly

  mvn gwt-process-resources

will not work since gwt-process-resources is just an id.

If there is no <phase> declaration in the pom then you might want to look at the documentation of the plugin and find the corresponding default phase. If you look at the documentation of the gwt plugin:

• gwt:i18n Binds by default to generate-sources.
• gwt:generateAsync Binds by default to the lifecycle phase: generate-sources.

How are goals triggered?

if you do

mvn compile

=> compile > generate-sources in maven lifecycle
=> maven execute gwt:i18n after gwt:generateAsync
=> executed in the order they are declared in pom.xml because they are bound to some phase "generate-sources"