ejb lookup failing with NamingException

Question

I\'ve added the following in my web.xml:

        ejb/userManagerBean
        Ses         


        

Answer 1

I think you want to access an EJB application (known as EJB module) from a web application in Sun Application Server, right ?

ok, let's go.

When you deploy an EJB into an application server, the application server gives it an address - known as global JNDI address - as a way you can access it (something like your address). It changes from an application server to another.

In JBoss Application Server, you can see global JNDI address (after starting it up) in the following address

http://127.0.0.1:8080/jmx-console/HtmlAdaptor

In Sun Application Server, if you want to see global JNDI address (after starting it up), do the following

Access the admin console in the following address

http://127.0.0.1:4848/asadmin

And click JNDI browsing

If your EJB IS NOT registered right there, there is something wrong

EJB comes in two flavors: EJB 2.1 and EJB 3.0. So what is the difference ?

Well, well, well...

Let's start with EJB 2.1

1. Create a Home interface

It defines methods for CREATING, destroying, and finding local or remote EJB objects. It acts as life cycle interfaces for the EJB objects. All home interfaces have to extend standard interface javax.ejb.EJBHome - if you a using a remote ejb object - or javax.ejb.EJBLocalHome - if you are using a local EJB object.

// a remote EJB object - extends javax.ejb.EJBHome
// a local EJB object - extends javax.ejb.EJBLocalHome
public interface MyBeanRemoteHome extends javax.ejb.EJBHome {

    MyBeanRemote create() throws javax.ejb.CreateException, java.rmi.RemoteException;

}

Application Server will create Home objects as a way you can obtain an EJB object, nothing else.

Take care of the following

A session bean’s remote home interface MUST DEFINE ONE OR MORE create methods. A stateless session bean MUST DEFINE exactly one method with no arguments.

...

throws clause MUST INCLUDE javax.ejb.CreateException

...

If your Home interface extends javax.ejb.EJBHome, throws clauses MUST INCLUDE the java.rmi.RemoteException. If it extends javax.ejb.EJBLocalHome, MUST NOT INCLUDE the java.rmi.RemoteException.

...

Each create method of a stateful session bean MUST BE NAMED create, and it must match one of the Init methods or ejbCreate methods defined in the session bean class. The matching ejbCreate method MUST HAVE THE SAME NUMBER AND TYPES OF ARGUMENTS. The create method for a stateless session bean MUST BE NAMED create but need not have a matching “ejbCreate” method.

---

Now create an business interface in order to define business logic in our EJB object

// a remote EJB object - extends javax.ejb.EJBObject
// a local EJB object - extends javax.ejb.EJBLocalObject
public interface MyBeanRemote extends javax.ejb.EJBObject {

    void doSomething() throws java.rmi.RemoteException;

}

Now take care of the following

If you are using a remote EJB object, remote interface methods MUST NOT EXPOSE local interface types or local home interface types.

...

If your Home interface extends javax.ejb.EJBObject, throws clauses MUST INCLUDE the java.rmi.RemoteException. If it extends javax.ejb.EJBLocalObject, MUST NOT INCLUDE the java.rmi.RemoteException.

---

Now our EJB

public class MyBean implements javax.ejb.SessionBean {

    // why create method ? Take a special look at EJB Home details (above)
    public void create() {
        System.out.println("create");
    }

    public void doSomething() throws java.rmi.RemoteException {
        // some code
    };

}

Now take care of the following

It MUST IMPLEMENTS javax.ejb.SessionBean. It defines four methods - not shown above: setSessionContext, ejbRemove, ejbPassivate, and ejbActivate.

Notice our bean DOES NOT IMPLEMENT our business interface because of EJB specification says:

For each method defined in the interface, there must be a matching method in the session bean’s class. The matching method must have:

• The same name
• The same number and types of arguments, and the same return type.
• All the exceptions defined in the throws clause of the matching method of the session bean class must be defined in the throws clause of the method of the local interface.

And YOU HAVE TO DECLARE a ejb-jar.xml file according to

    
        
            HelloWorldEJB
            br.com.MyBeanRemoteHome
            br.com.MyBeanRemote
            br.com.MyBeanLocalHome
            br.com.MyBeanLocal
            br.com.MyBean
            Stateless
            Container
        
    

If you do not have a local EJB object remove from the deployment descriptor above

br.com.MyBeanLocalHome
br.com.MyBeanLocal

If you do not have a remote EJB object remove from the deployment descriptor above

br.com.MyBeanRemoteHome
br.com.MyBeanRemote

And put in META-INF directory

Our jar file will contain the following

/META-INF/ejb-jar.xml
br.com.MyBean.class
br.com.MyBeanRemote.class
br.com.MyBeanRemoteHome.class

---

Now our EJB 3.0

// or @Local
// You can not put @Remote and @Local at the same time
@Remote
public interface MyBean {

    void doSomething();

}

@Stateless
public class MyBeanStateless implements MyBean {

    public void doSomething() {

    }

}

Nothing else,

In JBoss put jar file in

/server/default/deploy

---

In Sun Application Server access (after starting it up) admin console

http://127.0.0.1:4848/asadmin

And access EJB Modules in order to deploy your ejb-jar file

As you have some problems when deploying your application in NetBeans, i suggest the following

1. Create a simple Java library PROJECT (a simple jar without a main method)
2. Add /server/default/lib (contains jar files in order you retrieve your EJB's) jar files to your Java application whether you are using JBoss (I do not know which directory in Sun Application Server)
3. Implement code above

Now create another war PROJECT

1. Add our project created just above and add /client (contains jar files in order to access our EJB's). Again i do not know which directory in Sun Application Server. Ckeck out its documentation.
2. See its global mapping address as shown in the top of the answer

And implement the following code in your Servlet or something else whether you are using JBoss

public static Context getInitialContext() throws javax.naming.NamingException {

    Properties p = new Properties();
    p.put(Context.INITIAL_CONTEXT_FACTORY,        "org.jnp.interfaces.NamingContextFactory");
    p.put(Context.URL_PKG_PREFIXES, " org.jboss.naming:org.jnp.interfaces");
    p.put(Context.PROVIDER_URL, "jnp://127.0.0.1:1099");

    return new javax.naming.InitialContext(p);
}

Or the following whether you are using Sun Application Server - put the file appserv-rt.jar (I do not know which past contain appserv-rt.jar in Sun Application Server) in your classpath

public static Context getInitialContext() throws javax.naming.NamingException {

    return new javax.naming.InitialContext();

}

In order to access your EJB in our Servlet or something else

MyBeanRemote myBean = (MyBeanRemote) getInitialContext().lookup();

myBean.doSomething();

regards,