Why we should add @Stateless to an Entity in a Maven Project?

Question

When I created my first empty Entreprise Application with Maven, I had this error, even when I created an Entity:

    Invalid ejb jar it contains zero ejb
Note: 
1. A valid ejb jar requires at least one session, entity (1.x/2.x style), or message-driven bean. 
2. EJB3+ entity beans (@Entity) are POJOs and please package them as library jar. 
3. If the jar file contains valid EJBs which are annotated with EJB component level annotations (@Stateless, @Stateful, @MessageDriven, @Singleton), please check server.log to see whether the annotations were processed properly.

Entity.java:

package test;

import java.io.Serializable;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;


@javax.persistence.Entity
public class Entity implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
}

Then I found that the solution to this issue is to add @Stateless to the `Entity Class: package test;

import java.io.Serializable;
import javax.ejb.Stateless;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Stateless
@javax.persistence.Entity
public class Entity implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
}

It works fine, but now I want to know why I had to add this annotation to the Entity to work fine ?

The config details are:

Netbeans 8.1
Glassfish 4.1.1
pgAdmin III
Maven 3.5

The EAR module has the maven-ear-plugin configured as follows:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-ear-plugin</artifactId>
    <version>2.6</version>
    <configuration>
        <version>6</version>
        <defaultLibBundleDir>lib</defaultLibBundleDir>
    </configuration>
</plugin>

Does your "Enterprise Application" contain just the one WAR file? — Steve C, Jul 18 '17 at 09:51

score 1 · Answer 1 · answered Jul 18 '17 at 11:11

1

It's possible that the presence of that @Stateless annotation will cause weird stuff to happen at runtime, so you should remove that.

As your resulting jar contains zero EJBs then it's packaging type should be changed from ejb to jar.

Make sure that your maven-ear-plugin looks something like:

        <plugin>
            <artifactId>maven-ear-plugin</artifactId>
            <version>2.10.1</version>
            <configuration>
                <version>7</version>
                <defaultLibBundleDir>lib</defaultLibBundleDir>
                <modules>
                    <!-- no ejb module -->
                    <webModule>
                       ...
                    </webModule>
                </modules>
            </configuration>
        </plugin>

and your application should deploy properly.

Furthermore, as you're using GlassFish 4.x, you could dispense with the "Enterprise Application" altogether and just put everything in your WAR file which can then be deployed on it's own.

You can even add EJBs to the WAR later if you want.

These days you would only use an EAR when you're working on an ancient monolith. Make your build only as complicated as needed.

answered Jul 18 '17 at 11:11

Steve C

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this is my "ear pom file": `4.0.0 BookTest BookTest 1.0 pom BookTest BookTest-ear BookTest-web BookTest-ejb ` What should I remove ? – Mehdi Bouzidi Jul 18 '17 at 12:22
That is your parent pom, not your BookTest-ear pom. – Steve C Jul 18 '17 at 12:30
excuse me, this is it: ` org.apache.maven.plugins maven-compiler-plugin 2.3.2 org.apache.maven.plugins maven-ear-plugin 2.6 6 lib ` – Mehdi Bouzidi Jul 18 '17 at 12:35
That will probably work fine. You don't need the compiler-plugin at all because this module should not contain any Java source files. You can safely upgrade the version to 7 as well as the plugin version if you want. – Steve C Jul 18 '17 at 12:44
Yes this is should work but it unfortunately doesn't work – Mehdi Bouzidi Jul 18 '17 at 12:47
Do you have the same problem? Did you change the Maven packaging for the "BookTest-ejb" module (which is not really an EJB module)? – Steve C Jul 18 '17 at 12:50
Yes always the same – Mehdi Bouzidi Jul 18 '17 at 12:52
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/149483/discussion-between-steve-c-and-mehdi-bouzidi). – Steve C Jul 18 '17 at 12:52
can we do this later ? cause my Company's Security filter doesn't let me acces the chat link – Mehdi Bouzidi Jul 18 '17 at 12:53
I get it. The pom.xml for BookTest-ejb should **not** contain ejb. – Steve C Jul 18 '17 at 13:05
Please show me what the generated `application.xml` file looks like. Make sure that your EAR BookTest-ejb dependency has `ejb` removed – Steve C Jul 18 '17 at 13:42

Why we should add @Stateless to an Entity in a Maven Project?

1 Answers1