An example of Maven EAR project consists of an EJB interface, an EJB implementation and a WAR

Posted on Friday Mar 06, 2015 at 10:43PM in Maven

The project consists of following principal modules:

eartest-ejb-api: holds an EJB local interface named Hello. packaging=jar. no dependency.
eartest-ejb-impl: holds an EJB implementation named HelloImpl which implements Hello. packaging=ejb. depends on eartest-ejb-api.
eartest-war: holds an Servlet which has an injection point of Hello interface. depends on eartest-ejb-api.
eartest-ear: holds above 3 modules in the EAR.

Whole project is can be obtained from https://github.com/lbtc-xxx/eartest .

Structure of eartest-ear module

$ tree eartest-ear/target/eartest-ear
eartest-ear/target/eartest-ear
|-- META-INF
|   `-- application.xml
|-- eartest-ejb-impl-1.0-SNAPSHOT.jar
|-- eartest-war-1.0-SNAPSHOT.war
`-- lib
    `-- eartest-ejb-api-1.0-SNAPSHOT.jar

2 directories, 4 files

Structure of eartest-war module

$ tree eartest-war/target/eartest-war
eartest-war/target/eartest-war
|-- META-INF
`-- WEB-INF
    `-- classes
        `-- eartest
            `-- war
                `-- MyServlet.class

5 directories, 1 file

MyServlet can reference eartest-ejb-api-1.0-SNAPSHOT.jar because it’s placed under lib directory in the parent EAR. this packaging style is called as Skinny WAR.

Structure of eartest-ejb-api

$ tree eartest-ejb-api/target/classes
eartest-ejb-api/target/classes
`-- eartest
    `-- ejb
        `-- api
            `-- Hello.class

3 directories, 1 file

Structure of eartest-ejb-impl

$ tree eartest-ejb-impl/target/classes
eartest-ejb-impl/target/classes
|-- META-INF
|   `-- ejb-jar.xml
`-- eartest
    `-- ejb
        `-- impl
            `-- HelloImpl.class

4 directories, 2 files

A problem with IntelliJ IDEA

IntelliJ has an annoying issue: Maven support cannot handle skinny wars for EAR deployments : IDEA-97324. this brings unnecessary eartest-ejb-api into WEB-INF/lib inside the WAR and brings following exception. to avoid this, I need to put <scope>provided</scope> in dependency declaration for eartest-ejb-api in pom.xml of eartest-war.

Caused by: java.lang.IllegalStateException: JBAS011048: Failed to construct component instance
	at org.jboss.as.ee.component.BasicComponent.constructComponentInstance(BasicComponent.java:162)
	at org.jboss.as.ee.component.BasicComponent.constructComponentInstance(BasicComponent.java:133)
	at org.jboss.as.ee.component.BasicComponent.createInstance(BasicComponent.java:89)
	at org.jboss.as.ee.component.ComponentRegistry$ComponentManagedReferenceFactory.getReference(ComponentRegistry.java:149)
	at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$5.createInstance(UndertowDeploymentInfoService.java:1233)
	at io.undertow.servlet.core.ManagedServlet$DefaultInstanceStrategy.start(ManagedServlet.java:215) [undertow-servlet-1.1.0.Final.jar:1.1.0.Final]
	... 27 more
Caused by: java.lang.IllegalArgumentException: Can not set eartest.ejb.api.Hello field eartest.war.MyServlet.hello to eartest.ejb.api.Hello$$$view17
	at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167) [rt.jar:1.8.0_20]
	at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171) [rt.jar:1.8.0_20]
	at sun.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81) [rt.jar:1.8.0_20]
	at java.lang.reflect.Field.set(Field.java:758) [rt.jar:1.8.0_20]
	at org.jboss.as.ee.component.ManagedReferenceFieldInjectionInterceptorFactory$ManagedReferenceFieldInjectionInterceptor.processInvocation(ManagedReferenceFieldInjectionInterceptorFactory.java:108)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
	at org.jboss.invocation.WeavedInterceptor.processInvocation(WeavedInterceptor.java:53)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
	at org.jboss.as.ee.component.AroundConstructInterceptorFactory$1.processInvocation(AroundConstructInterceptorFactory.java:28)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
	at org.jboss.as.ee.concurrent.ConcurrentContextInterceptor.processInvocation(ConcurrentContextInterceptor.java:45) [wildfly-ee-8.2.0.Final.jar:8.2.0.Final]
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
	at org.jboss.invocation.ContextClassLoaderInterceptor.processInvocation(ContextClassLoaderInterceptor.java:64)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
	at org.jboss.invocation.InterceptorContext.run(InterceptorContext.java:326)
	at org.jboss.invocation.PrivilegedWithCombinerInterceptor.processInvocation(PrivilegedWithCombinerInterceptor.java:80)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
	at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
	at org.jboss.as.ee.component.BasicComponent.constructComponentInstance(BasicComponent.java:160)
	... 32 more

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