JAR library in WAR module not seen

Question

I have Maven project with WAR and EAR module. EAR module has WAR as a dependency and is included as a war module in maven-ear-plugin. There's also JAR library added in EAR module and is used by WAR module.

EAR module pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.example</groupId>
        <artifactId>MyApp</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <artifactId>MyEar</artifactId>
    <packaging>ear</packaging>

    <dependencies>
            <dependency>
                <groupId>com.example</groupId>
                <artifactId>MyWar</artifactId>
                <version>0.0.1-SNAPSHOT</version>
                <type>war</type>
            </dependency>
            <dependency>
                <groupId>com.example</groupId>
                <artifactId>MyJar</artifactId>
            </dependency>
        </dependencies>

        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-ear-plugin</artifactId>
                    <version>2.9</version>
                    <configuration>
                        <modules>
                            <jarModule>
                                <groupId>com.example</groupId>
                                <artifactId>MyJar</artifactId>
                            </jarModule>
                            <webModule>
                                <groupId>com.example</groupId>
                                <artifactId>MyWar</artifactId>
                                <contextRoot>/MyWebApp</contextRoot>
                            </webModule>
                        </modules>
                        <version>6</version>
                    </configuration>
                </plugin>
            </plugins>
        </build>

</project>

And WAR module pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.example</groupId>
        <artifactId>MyApp</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <artifactId>MyWar</artifactId>
    <packaging>war</packaging>

    <dependencies>
        <dependency>
            <groupId>com.example</groupId>
            <artifactId>MyJar</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.2.2</version>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

I'm trying to build EAR that includes MyWar and MyJar in root. The problem is that if I use EAR pom like the one above, MyJar library is not "seen" by MyWar.

What am I missing here?

Have you defined `ear`? Furthermore it would be helpful to have the full pom file otherwise it's hard to guess... — khmarbaise, Dec 06 '18 at 07:45
@khmarbaise Yes, `packaging` is set to `ear`. Full EAR pom is added. — peterremec, Dec 06 '18 at 07:50
@khmarbaise Should I put MyJar in WAR's manifest file? How can I do that in Maven? — peterremec, Dec 06 '18 at 07:56
If this is the literal pom then I don't really see how this even builds, given that you define no dependency version for the 'myJar' module. — Gimby, Dec 06 '18 at 09:45
@Gimby This is a literal EAR pom. JAR version is defined in parent project pom. — peterremec, Dec 06 '18 at 09:49

score 1 · Accepted Answer · answered Dec 06 '18 at 09:36

The only modules that should be in the root of the EAR archive are ejb-jars, wars and rars.

Utility library jars should be placed in a "lib" directory within the EAR.

You just need to add one line to your EAR plugin configuration to accomplish this:

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-ear-plugin</artifactId>
                <version>2.9</version>
                <configuration>
                    <modules>
                        <jarModule>
                            <groupId>com.example</groupId>
                            <artifactId>MyJar</artifactId>
                        </jarModule>
                        <webModule>
                            <groupId>com.example</groupId>
                            <artifactId>MyWar</artifactId>
                            <contextRoot>/MyWebApp</contextRoot>
                        </webModule>
                    </modules>
                    <version>6</version>
                    <defaultLibBundleDir>lib</defaultLibBundleDir>  <--- this!
                </configuration>
            </plugin>

If you're going to be using EAR files you should familiarise yourself with the class visibility rules for the various modules within them. This is loosely summarised in My ear is not able to find ejb module classes.

In general you should not be using EAR files these days. In most cases a simple WAR file will be sufficient

thank you for your help. I managed to put jars in ear as I've wanted and my app works. Just out of curiosity, why shouldn't I use EAR files? — peterremec, Dec 07 '18 at 07:58
Because not very many people understand the class visibility rules in them. A WAR file is much simpler (you can put EJBs in them now). Generally everyone has enough complexity to deal with without worrying whether a component can see your classes when they're in an EAR file. — Steve C, Dec 07 '18 at 09:59

JAR library in WAR module not seen

1 Answers1