Primi passi con le EJB e JBoss

[Fabrizio73]

Sto compiendo i primi passi con le EJB.

Come container sto adoperando JBoss 3.2.0 che a sua volta si appoggia su Tomcat 4.1.24.

Ho scritto uno Stateless Session Bean che dovrebbe semplicemente restituire la stringa "Hello World".

La Home Interface (HelloWorldHome.java):

package helloWorldEjb;

import javax.ejb.EJBHome;
import java.rmi.RemoteException;
import javax.ejb.CreateException;

public interface HelloWorldHome extends EJBHome {
    public HelloWorld create() throws RemoteException, CreateException;
}

La Remote Interface (HelloWorld.java):

package helloWorldEjb;

import javax.ejb.EJBObject;
import java.rmi.RemoteException;

public interface HelloWorld extends EJBObject{
    public String hello() throws RemoteException;
}

L'implementazione del Bean (HelloWorldBean.java):

package helloWorldEjb;

import javax.ejb.SessionBean;
import javax.ejb.SessionContext;
import javax.ejb.EJBException;
import java.rmi.RemoteException;

public class HelloWorldBean implements SessionBean {
    private SessionContext ctx;
    
    public void ejbActivate() throws EJBException, RemoteException {
        System.out.println("HelloWorldBean: ejbActivate()");
    }
    
    public void ejbPassivate() throws EJBException, RemoteException {
        System.out.println("HelloWorldBean: ejbPassivate()");
    }
    
    public void ejbRemove() throws EJBException, RemoteException {
        System.out.println("HelloWorldBean: ejbRemove()");
    }
    
    public void ejbCreate() {
        System.out.println("HelloWorldBean: ejbCreate()");
    }
    
    public void setSessionContext(SessionContext sessionContext) throws EJBException, RemoteException {
        ctx = sessionContext;
    }
    
    public String hello() {
        System.out.println("HelloWorldBean: hello()");
        return "Hello World";
    }
}

Il Deployment Descriptor (ejb-jar.xml):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ejb-jar PUBLIC
      "-//Sun Microsystems, Inc.//DTD Enterprise JavaBeans 2.0//EN"
      "http://java.sun.com/dtd/ejb-jar_2_0.dtd">

<ejb-jar>
    <description>JBoss Stateless Session Bean Test</description>
    <display-name>Hello World EJB</display-name>
    <enterprise-beans>
        <session>
            <ejb-name>HelloWorld</ejb-name>
            <home>helloWorldEjb.HelloWorldHome</home>
            <remote>helloWorldEjb.HelloWorld</remote>
            <ejb-class>helloWorldEjb.HelloWorldBean</ejb-class>
            <session-type>Stateless</session-type>
            <transaction-type>Bean</transaction-type>
        </session>
    </enterprise-beans>
</ejb-jar>

Le tre classi vengono compilate correttamente da Forte for Java 4 CE.

Ho quindi creato l'archivio helloWorld.jar contenente le tre classi compilate e la directory META-INF contenente il Deployment Descriptor (ejb-jar.xml).

Fatto questo, ho copiato il helloWorld.jar nella directory C:\Appl\jboss-tomcat\server\default\deploy, dopo aver avviato JBoss.

Il deployment è avvenuto correttamente, come segnalato da JBoss.

A questo punto ho scritto il client (HelloWorldClient.java):

import java.util.Hashtable;
import javax.naming.Context;
import javax.naming.InitialContext;
import helloWorldEjb.HelloWorldHome;
import javax.rmi.PortableRemoteObject;
import helloWorldEjb.HelloWorld;

public class HelloWorldClient {
    public static void main(String[] args) {
        Hashtable env = new Hashtable();
        
        env.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
        env.put(Context.PROVIDER_URL, "localhost:1099");
        env.put("java.naming.factory.url.pkgs", "org.jboss.naming:org.jnp.interfaces");
        
        try {
            Context ctx = new InitialContext(env);
            
            Object obj = ctx.lookup("HelloWorld");
            HelloWorldHome home = (HelloWorldHome)PortableRemoteObject.narrow(obj, HelloWorldHome.class);
            HelloWorld helloWorld = home.create();
            
            System.out.println(helloWorld.hello());
            helloWorld.remove();
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("Eccezione: " + e.getMessage());
        }
    }
}

Prima di avviare il client ho inserito nel class-path i seguenti JAR:
- j2ee.jar
- jboss-common-client.jar
- jboss-client.jar
- jboss-system-client.jar
- jbosssx-client.jar
- jnp-client.jar
- log4j.jar
- helloWorld.jar

All'atto dell'esecuzione del client però, si verifica la seguente eccezione:

java.lang.NoClassDefFoundError: Lorg/jboss/tm/TransactionPropagationContextFactory;
        at java.lang.Class.getDeclaredFields0(Native Method)
        at java.lang.Class.privateGetDeclaredFields(Class.java:1494)
        at java.lang.Class.getField0(Class.java:1727)
        at java.lang.Class.getDeclaredField(Class.java:1189)
        at java.io.ObjectStreamClass.getDeclaredSUID(ObjectStreamClass.java:1430)
        at java.io.ObjectStreamClass.access$400(ObjectStreamClass.java:45)
        at java.io.ObjectStreamClass$3.run(ObjectStreamClass.java:331)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.io.ObjectStreamClass.<init>(ObjectStreamClass.java:329)
        at java.io.ObjectStreamClass.lookup(ObjectStreamClass.java:249)
        at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:449)
        at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1521)
        at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1435)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1626)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1274)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:324)
        at java.util.HashMap.readObject(HashMap.java:986)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:324)
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:824)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1746)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1646)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1274)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1845)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1769)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1646)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1274)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:324)
        at org.jboss.proxy.ClientContainer.readExternal(ClientContainer.java:109)
        at java.io.ObjectInputStream.readExternalData(ObjectInputStream.java:1686)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1644)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1274)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1845)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1769)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1646)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1274)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:324)
        at java.rmi.MarshalledObject.get(MarshalledObject.java:135)
        at org.jnp.interfaces.MarshalledValuePair.get(MarshalledValuePair.java:30)
        at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:514)
        at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:471)
        at javax.naming.InitialContext.lookup(InitialContext.java:347)
        at HelloWorldClient.main(HelloWorldClient.java:29)
Exception in thread "main"

Dov'è il problema?
Cosa ho sbagliato?

Infinite grazie a chiunque possa aiutarmi!

[Fabrizio73]

Ok... ho risolto da me!

Per chi fosse interessato: il problema è nel class-path del client, invece di includere tutti quei files, basta includere jbossall-client.jar

[dr.stein]

tutto questo per un'hello world ?!?!?!?

[Fabrizio73]

Già ...

[Passy]

Originally posted by "Fabrizio73"

Già ...

Cosa hai fatto per risolvere il problema???

Ciao

[Fabrizio73]

Per l'esecuzione del client basta inserire nel class-path jbossall-client.jar.