Question

I’ve used a Maven archetype (webapp-javaee6) to create a new Java EE 6 project but don’t understand why certain things are put inside the build element of the POM. To be specific I don’t understand why the javaee-endorsed-api.jar is copied over to the endorsed directory. According to the answer to this question, this is needed for compilation but my project compiles fine when I remove the related plugin element under build.

Since javax:javaee-web-api is already provided as a dependency in the POM, can this not be used for compiling?

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.3.2</version>
            <configuration>
                <source>1.6</source>
                <target>1.6</target>
                <compilerArguments>
                    <endorseddirs>${endorsed.dir}</endorseddirs>
                </compilerArguments>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <version>2.1</version>
            <executions>
                <execution>
                    <phase>validate</phase>
                    <goals>
                        <goal>copy</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>${endorsed.dir}</outputDirectory>
                        <silent>true</silent>
                        <artifactItems>
                            <artifactItem>
                                <groupId>javax</groupId>
                                <artifactId>javaee-endorsed-api</artifactId>
                                <version>6.0</version>
                                <type>jar</type>
                            </artifactItem>
                        </artifactItems>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Answer 1

It should compile, because there is also a dependency to this artifact:

<dependencies>
    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-web-api</artifactId>
        <version>6.0</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

Maven manual page describes provided as follows:

This is much like compile, but indicates you expect the JDK or a container to provide the dependency at runtime. For example, when building a web application for the Java Enterprise Edition, you would set the dependency on the Servlet API and related Java EE APIs to scope provided because the web container provides those classes. This scope is only available on the compilation and test classpath, and is not transitive.

So in my opinion copying this dependency has no impact on compiling.

However archetype’s author wanted for some reason to copy Java EE 6 API package to endorsed directory. This might be helpful if you decide to start Jetty server and do some testing in “Test Phase” (for example with JUnit).

If you’re not using it – just remove it.