EJB3 Session bean and JBoss 5

[Logan Lee]

Hello,
I am trying to learn EJB3 with the book "EJB3 in action".
As a starting point, I wanted to create a very simple EJB3 stateless session bean that returns a String object.
As a client I am using a simple servlet.
The application server I am using is JBoss 5.1.0.GA.

I have created:
- ICatalogService: the remote interface
- CatalogService: the stateless session bean
- ejb-jar.xml deployment descriptor

Unfortunately, when I deploy the EAR file, I get this error:

* EJB CatalogService has defined EJB2.x remote component interface of be.work
.apps.bookstore.ejb.service.ICatalogService but has no home; ; Incomplete EJB2.x
 View [JBMETA-130]

I already had a look at the new ejb-jar XSD at http://java.sun.com/xml/ns/javaee/ejb-jar_3_0.xsd
and it states:

Either both the local-home and the local elements or both the home and the remote elements must be specified.

I now am a bit confused. I thought the EJB Home interface was something of the past (EJB 2.x) and wasn't needed anymore in EJB3.
How can I solve this?
Thanks.

This is my servlet:

public class CatalogServlet extends HttpServlet {
 @EJB
    private ICatalogService catalogService;

    public void doGet(HttpServletRequest request,
                      HttpServletResponse response)
            throws ServletException, IOException
    {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("Invoking session bean...");
        out.println(catalogService.getBookOverview());
        out.println("... done");
        out.close();
    }

    public void doPost(HttpServletRequest request,
                       HttpServletResponse response)
            throws ServletException, IOException
    {
        doGet(request,response);
    }

The remote interface:

@Remote
public interface ICatalogService {
    public String getBookOverview();
}

The bean:

@Stateless(name="CatalogService")
public class CatalogService implements ICatalogService {

    public CatalogService(){    
    }

    public String getBookOverview(){
        return "a list of books";
    }
}

ejb-jar.xml:

<ejb-jar version="3.0">
    <enterprise-beans>
        <session>
            <ejb-name>CatalogService</ejb-name>
            <remote>be.work.apps.bookstore.ejb.service.ICatalogService</remote>
            <ejb-class>be.work.apps.bookstore.ejb.service.CatalogService</ejb-class>
            <session-type>Stateless</session-type>
            <transaction-type>Container</transaction-type>
        </session>
    </enterprise-beans>
    <assembly-descriptor>
        <container-transaction>
            <method>
                <ejb-name>CatalogService</ejb-name>
                <method-name>*</method-name>
            </method>
            <trans-attribute>Required</trans-attribute>
        </container-transaction>
        <security-role>
            <role-name>users</role-name>
        </security-role>
    </assembly-descriptor>
</ejb-jar>

[Jaikiran Pai]

First of all, for EJB3 you no longer need the ejb-jar.xml. But if you want to package it then its OK too.

EJB CatalogService has defined EJB2.x remote component interface of be.work.apps.bookstore.ejb.service.ICatalogService but has no home; ; Incomplete EJB2.x View [JBMETA-130]

<remote>be.work.apps.bookstore.ejb.service.ICatalogService</remote>  

Unfortunately, one of the most common confusion with the remote/local in EJB3 is the use of the remote/business-remote (or local/business-local). A "remote" element in the xml represents the EJB2.x remote interface, which is expected to extend from EJBObject. Whereas, the business-remote element is what needs to be used for EJB3 beans which expose the POJO interface. So in your example you have to change it to:

<business-remote>be.work.apps.bookstore.ejb.service.ICatalogService</business-remote> 

[Logan Lee]

Thanks Jaikiran, that solved the deployment problem. (Strange that in the EJB3 in action book they use remote/local)

but, now I receive a nullpointer in my servlet: catalogService is null. It seems the bean isn't injected...

@EJB  
private ICatalogService catalogService;

so I decided to write a small client to test the bean via JNDI lookup. the lookup fails with a ClassCastException.
Exception in thread "main" java.lang.ClassCastException: javax.naming.Reference

Java client:

public class LocalClientTestClass {
    public static void main (String [] args) throws Exception {
        System.out.println("calling ejb");
        InitialContext ctx = new InitialContext();
	ICatalogService service = (ICatalogService) ctx.lookup("bookstore/CatalogService/remote");

jndi.properties:

java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory
java.naming.provider.url=jnp://localhost:1099

As you can see the bean is successfully mapped to a JNDI name:

09:19:45,703 INFO  [JBossASKernel] installing bean: jboss.j2ee:ear=bookstore.ear
,jar=ejb-jar-0.0.1-SNAPSHOT.jar,name=CatalogService,service=EJB3
09:19:45,703 INFO  [JBossASKernel]   with dependencies:
09:19:45,703 INFO  [JBossASKernel]   and demands:
09:19:45,703 INFO  [JBossASKernel]      jboss.ejb:service=EJBTimerService
09:19:45,703 INFO  [JBossASKernel]   and supplies:
09:19:45,718 INFO  [JBossASKernel]      jndi:bookstore/CatalogService/remote
09:19:45,718 INFO  [JBossASKernel]      jndi:bookstore/CatalogService/remote-be.
work.apps.bookstore.ejb.service.ICatalogService
09:19:45,718 INFO  [JBossASKernel]      Class:be.work.apps.bookstore.ejb.serv
ice.ICatalogService
09:19:45,718 INFO  [JBossASKernel] Added bean(jboss.j2ee:ear=bookstore.ear,jar=e
jb-jar-0.0.1-SNAPSHOT.jar,name=CatalogService,service=EJB3) to KernelDeployment
of: ejb-jar-0.0.1-SNAPSHOT.jar
09:19:45,718 INFO  [EJB3EndpointDeployer] Deploy AbstractBeanMetaData@1df897{nam
e=jboss.j2ee:ear=bookstore.ear,jar=ejb-jar-0.0.1-SNAPSHOT.jar,name=CatalogServic
e,service=EJB3_endpoint bean=org.jboss.ejb3.endpoint.deployers.impl.EndpointImpl
 properties=[container] constructor=null autowireCandidate=true}
09:19:45,765 INFO  [SessionSpecContainer] Starting jboss.j2ee:ear=bookstore.ear,
jar=ejb-jar-0.0.1-SNAPSHOT.jar,name=CatalogService,service=EJB3
09:19:45,765 INFO  [EJBContainer] STARTED EJB: be.work.apps.bookstore.ejb.ser
vice.CatalogService ejbName: CatalogService
09:19:45,781 INFO  [JndiSessionRegistrarBase] Binding the following Entries in G
lobal JNDI:

        bookstore/CatalogService/remote - EJB3.x Default Remote Business Interfa
ce
        bookstore/CatalogService/remote-be.work.apps.bookstore.ejb.service.IC
atalogService - EJB3.x Remote Business Interface

09:19:46,000 INFO  [TomcatDeployment] deploy, ctxPath=/war

Also in the JBoss JMX JNDI Global NS everything looks fine.

  +- bookstore (class: org.jnp.interfaces.NamingContext)
  |   +- CatalogService (class: org.jnp.interfaces.NamingContext)
  |   |   +- remote-be.work.apps.bookstore.ejb.service.ICatalogService (class: Proxy for: be.work.apps.bookstore.ejb.service.ICatalogService)
  |   |   +- remote (class: Proxy for: be.work.apps.bookstore.ejb.service.ICatalogService)

I'm puzzled. What am I doing wrong here?

[Jaikiran Pai]

Logan Lee wrote:
but, now I receive a nullpointer in my servlet: catalogService is null. It seems the bean isn't injected...

@EJB  
private ICatalogService catalogService;

Your web.xml will require the 2.5 xsd https://coderanch.com/t/426854/EJB-Other-Java-EE-Technologies/java/EJB-doing-nothing-jboss-GA#1894841

Logan Lee wrote:
so I decided to write a small client to test the bean via JNDI lookup. the lookup fails with a ClassCastException.
Exception in thread "main" java.lang.ClassCastException: javax.naming.Reference

For this you will require the jbossall-client.jar and all the jar files listed in the META-INF/MANIFEST.MF of that jar, to be present in the client's classpath. Those jars are available in the JBOSS_HOME/client folder.

[Logan Lee]

Thanks for the advice Jaikiran, I am able to access the EJB now.
Changing the XSD to version 2.5 solved part of the Direct Injection problem, there was another catch.

After I changed the web-app element to:

<web-app version="2.5"
     xmlns="http://java.sun.com/xml/ns/javaee"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

I stumbled upon the following error:
java.lang.IllegalStateException: Resolution should not happen via injection container

Apparently this is a bug:

When a servlet is packaged standalone (outside ear) and an EJB is packaged standalone, the EJB can't be injected into the servlet without specifying a JNDI name somewhere.

https://jira.jboss.org/jira/browse/JBAS-6332

So to solve this I added the mappedName attribute to the @EJB annotation. The mappedName element should contain the JNDI lookup name of your interface(remote or local)

@EJB(mappedName = "bookstore/CatalogService/remote")

[Csaba Toth]

Jaikiran Pai wrote:

Logan Lee wrote:
so I decided to write a small client to test the bean via JNDI lookup. the lookup fails with a ClassCastException.
Exception in thread "main" java.lang.ClassCastException: javax.naming.Reference

For this you will require the jbossall-client.jar and all the jar files listed in the META-INF/MANIFEST.MF of that jar, to be present in the client's classpath. Those jars are available in the JBOSS_HOME/client folder.

I faced this exception during test runs. I added the JBOSS_HOME/client folder to the classpath of the xyzTest.java file, but I still get the exception. What am I doing wrong?

[Csaba Toth]

Csaba Toth wrote:

Jaikiran Pai wrote:
I faced this exception during test runs. I added the JBOSS_HOME/client folder to the classpath of the xyzTest.java file, but I still get the exception. What am I doing wrong?

Additional comments:
1. Only my test runs didn't work, when I deployed the application it could communicate. So there must be some problem with the difference between the execution environment, version numbers of jars, classpath in case of the test. I even installed the 5.1.0.GA jbossall-client from the JBOSS_HOME/client directory into my Maven repository, to use exactly the same versions. I use the jdk6 version of 5.1.0.GA JBoss, 1.6.0_21 SUN JDK.

2. if I remove the ejb-jar.xml from my EJB module, my app deploys OK, but it can't find the EJB any more, so not just the tests doesn't work, but the real life app any more.