A tough one for EJB experts - Stateless session bean spec question

I am busy learning more about EJBs and came across something confusing regarding the legal operations in the various container callback methods for stateless session beans.
Specifically, the EJB spec states that in the ejbCreate() method, the SessionContext can be used to obtain a reference to the EJB Object. Now this makes perfect sense with stateful session beans, since the ejbCreate() method isn't called until a client is creating a bean and the container has linked that bean to the client's EJB Object. However, it is my understanding that when it comes to stateless session beans, the container creates the beans and adds them to the bean pool at its leisure. It is not until a business method is called by a client that a stateless bean is actually linked to an EJB object. So, how is it that a stateless bean could ever obtain a reference to an EJB Object from within ejbCreate(). Which EJB Object would it be linked to? This operation just doesn't appear to make sense in that context.
Can anyone clarify this for me?

Interesting question. I have such questions all the time! Here's a link to a similar discussion
http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=70&t=000905
Also, I tried this using Weblogic 8.1. Tried to access the EJBObject in ejbCreate before any business method was invoked. I did this by specifying a value for initial-beans-in-free-pool and found that the hash code for the EJBObject was the same for all the bean instances that were created on startup.
I then invoked a business method and accessed the EJBObject in that method. Again the hash code for the object was the same as the one created on startup.
Seemed to be that there is a 1:n relation between the EJBObject and bean instances.
This may be container specific. The spec says the user should be able to invoke the getEJBObject() method in ejbCreate(), its upto the container to comply with it.

Similar Messages

EJB: Stateless Session Bean create() Question.

Lets say I have a stateless session bean that fetches data from my database. The point of the bean is to just do large SQL searches and funnel data back to the client. The prolem I have is that I am somehow fighting memory leaks. Despite having checked the code a number of times, the memory usage on my appserver continues to climb no matter what I do. I have theorized that the problem might be in the way Im using ma DataFetchBean (DFB).
When I start the client, he obtains a user session. This is a stateful session bean that he uses for almost all communication with the server. Then I call "getDataFetchBean" in the user session which calls DataFetchBeanHome.create(). Then the client holds onto the returned reference, using it for the live of his connection. As he disconnects, he calls remove on the bean.
Question is this:
1) Is it better for me to call create() prior to each call to the stateless session bean ?
2) Do you have any theories on why im loosing memory with this setup?
TIA
-- Rob

1. But I thought you were using a 'stateful session bean'?
2. For stateless session beans, there is no direct link between a remote reference and an instance of the bean. It is safe to hang on to the remote reference as long as you would like, of course it may go stale if the server dies. You will also find that the create() method does not actually contact the server, so doing it each usage costs very little. So, either way you should be fine.
3. As for memory leaks, make sure that you are closing all statements, result sets, etc. promptly. These are commonly the problem. Also, use hprof or some other profile tool to determine what types of data you are allocating and (with better tools) what types of data you may be holding on to references to.
Chuck

Java.io in J2ee stateless session bean, general questions about debugging

Doing conventional Java IO (with java.io functions and classes such as
PrintWriter and println) in a Enterprise bean has been discussed before
in this and other forum. We know that the EJB specification says not to do it.
(For example the EJB 2.0 spec, 24.1.2) says that an enterprise
bean must not use the java.io package to attempt to access files and
directories int he file system."
The discussion in various forums including this one is that
a) using java.io in a bean would impact portability, ability to
move the bean for load balancing
b) However, this is not always an an issue and it may be reasonable
to use these functions anyway. e. g. see the response by "maozhoulu"
on Jun 21, 2002.
I tried it in Sun Application Server Nine in my stateless Session Bean:
package RS;
import RS.CourseHome;
import RS.CoursePK;
import java.rmi.RemoteException;
import javax.naming.InitialContext;
import javax.naming.Context;
import javax.rmi.PortableRemoteObject;
import javax.ejb.EJBException;
import java.io.*;
public class AddCourseBean implements javax.ejb.SessionBean {
   public void ejbCreate(){};
   public void CreateCourse (int CourseNumber, String CourseName) {
    try {
     System.out.println("in Create Course");
     PrintWriter F = null;
     try {
      F = new PrintWriter (new FileOutputStream("/tmp/v/af"));
     catch (java.io.FileNotFoundException fe){}
     F.println ("here zero");F.flush();
     InitialContext jndiContext = new InitialContext();
     F.println ("here one");F.flush();
     Object o = jndiContext.lookup("ejb/X");
         ...I got a Null pointer exception on the line:
"F.println("here zero"); Is there anyway one can do simple debugging with print lines in one's beans?
Or is there something obviousthat I am overlooking? (I saw mention of doing
debugging with System.out.println but to where would the bean write?)
I tried using the Jakarta Commons Logging, but I got a
java.lang.NoClassDefFoundError on org/apache/commons/logging/LogFactory
Which logging system does one use in GlassFish, hopefully one with minimal
configuration? I want to do some debugging, not set up logging for a full
enterprise system.
Thanks for your insight and advice.
Dr. Laurence Leff, Associate Professor of Computer Science WIU ST447 61455
Pager 309 367 0787, Fax 309 298 2302

My apology for posting this message twice. I looked for it before and
did not see it. I thought I forget to click the "Post message" button.
Also, I did resolve one problem. System.out.println does go to
the log file, which in my case turned out to be:
/opt/j2ee/SUNWappserver/domains/domain1/logs/server.log
(Obvously, the first part would vary based upon where you installed your
Application Server Nine.)
However, it would be nice if there was some way to use FILE I/O inside of
beans. I am teaching some J2EE in the graduate software engineering course,
and I believe this would be pedagogically sound even if other techniques
would be appropriate for a production environment.
Thanks for your patience with this problem and my duplicate post.

Multiple inheritance in remote interfaces for EJB 3.0 session beans on Webl

Hi All,
We started migration from EJB 2.1(WLS 8.1) to EJB 3.0(WLS 10.3.2) and identified few serious problems. One of them is related with multiple business interfaces inheritance. I wrote simple example that presents point of the problem.
we have session bean AImpl:
+@Stateless(name="A")+
+@Remote({A.class})+
+@TransactionAttribute(TransactionAttributeType.REQUIRED)+
+public class AImpl implements A {+
+@Override+
+public void writeA() {+
System.out.println("A");
+}+
+@Override+
+public void writeB() {+
System.out.println("B");
+}+
+@Override+
+public void writeC() {+
System.out.println("C");
+}+
+}+
with remote interface A:
+@Remote+
+@JNDIName(A.JNDI_NAME)+
+public interface A extends B, C {+
public static String JNDI_NAME = "A_JNDI_NAME";
void writeA();
+}+
As you can see A extends B, and C. Definition of both interfaces is very simple:
+public interface B {+
void writeB();
+}+
+public interface C {+
void writeC();
+}+
Everything looks nice until we want to invoke some method on AImpl bean. For above implementation code:
A a = ctx.lookup(A. JNDI_NAME);
a.writeA();
a.writeB();
a.writeC();
writes down ”A \n B” and throws exception:
caused by: java.lang.NoSuchMethodException: pl.gov.arimr.zszik.bazowe.slowniki.ejb.A_vt0zts_AImpl_1032_WLStub.*writeC()*
at java.lang.Class.getMethod(Class.java:1605)
at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.getTargetMethod(RemoteBusinessIntfProxy.java:165)
at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.invoke(RemoteBusinessIntfProxy.java:57)
so.. in stub generated by WLS there is no method from interface C ! What more interesting after small change in interface A rely on change in interface implementation order from B, C to C, B (+public interface A extends C, B {+) server writes down only A and I have stack like below:
Caused by: java.lang.NoSuchMethodException: pl.gov.arimr.zszik.bazowe.slowniki.ejb.A_vt0zts_AImpl_1032_WLStub.*writeB()*
at java.lang.Class.getMethod(Class.java:1605)
at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.getTargetMethod(RemoteBusinessIntfProxy.java:165)
at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.invoke(RemoteBusinessIntfProxy.java:57)
After this experience I came up with suspicion that Weblogic 10.3 does not support inheritance from multiple interfaces in one “generation”. Instead of that it takes only the first interface from the list.
Does anybody have some experience with such a situation? maybe someone have an idea how to work around this problem?

This is Not Supported in WebLogic that the Remote Interface extends other Interfaces. Because Annotation Processor just looks up inside the implemented interface methods. The actual interface which is Implemented by the Bean Class. So the Methods declared inside the Interface B and Interface C will be ignored and will not be available as part of the generated Stubs. Thats why u are getting NoSuchMethodError.
You can even contact Oracle Support on this...there are 3-4 Cases on it. And the Solution is Work As Designed.
Workaround is : edit your interface A as following
Declare all the Business Methods only in the Remote Interface and not inside it's Super Interfaces.
Example:
@Stateless(name="A")
@Remote({A.class})
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public class AImpl implements A {
@Override
public void writeA() {
System.out.println("A");
@Override
public void writeB() {
System.out.println("B");
@Override
public void writeC() {
System.out.println("C");
@Remote
@JNDIName(A.JNDI_NAME)
public interface A extends B, C {
public static String JNDI_NAME = "A_JNDI_NAME";
void writeA();
void writeB();
void writeC();
Thanks
Jay SenSharma
http://jaysensharma.wordpress.com (WebLogic Wonders Are Here)

Ejb 3 stateless session bean eclipse glassfish runtime error

trying to get a simple stateless session ejb 3 connected to a jsp using eclipse and glassfish. I have the two projects compiling, deploying, and in archives. but i am getting an error in my jsp which states it can't find my 'ejb' package which holds my created class files. I have looked at many examples on line and I can't find anything to point me in the right direction. please help!

So you have 1 war file deployed and 1 ejb module deployed. Does the war file contain the interface class of the ejb? When deploying I tend to create a separate jar containing the interfaces to the ejbs that my web app will use and add it to WEB-INF/lib.
Also post the stack trace of the Exception you are getting in case there is somthing else in it. (Just the juciy bits - I know how big Glassfish stacks can be!)
m

Stateless session Bean - xml and ejb-jar.xml file ???

Dear Experts,
Stateless-session bean
For Creating an ear file
we need ejb-jar.xml and weblogic-ejb-jar.xml files
Is these files are already available
or we have to type these files ??
Advance Thanks
Rengaraj.R

My best advice: surrender to use an IDE.
You wonder sometimes at how much productivity (read as 'time') could be wasted by doing something that could be done automatically. For a learning experience or a once only exercise is fine but as a routine thing, not worth it.
Cheers

What's s the best automated route from stateless session bean class to EJB?

Hi,
I have an application that generates stateless session bean classes.
For any given stateless session bean class, I would like to build an EJB, moreover, I would like to automate the process as much as possible.
I'd rather not rely on a full blown third party IDE.
I reckon could write a set of java classes that could analyse the session bean class and generate the home and remote interface and a basic deployment descriptor.
That said, I have no doubt that I would be renventing the wheel.
But I am struggling to find a utility/class of the appropriate granularity in the public domain.
I am wide open to any feedback on approaches people may have taken and the pros and pitfalls.
I fully realise my question is quite unspecific, but I really wanted to get some feedback and start a discussion. Since, I am sure there is no 'correct' answer.
Most kind regards,
Simon.

My best advice: surrender to use an IDE.
You wonder sometimes at how much productivity (read as 'time') could be wasted by doing something that could be done automatically. For a learning experience or a once only exercise is fine but as a routine thing, not worth it.
Cheers

Problem Deploying EJB3 Stateless session bean in Jboss4.0.3

Hi All,
I have developed an EJB 3 Stateless session bean and tried to deploy in JBoss 4.0.3 , But i get the following Exception.
javax.naming.NameNotFoundException: ejb not bound
at org.jnp.server.NamingServer.getBinding(NamingServer.java:491)
at org.jnp.server.NamingServer.getBinding(NamingServer.java:499)
at org.jnp.server.NamingServer.getObject(NamingServer.java:505)
at org.jnp.server.NamingServer.lookup(NamingServer.java:249)
at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:610)
at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:572)
at javax.naming.InitialContext.lookup(InitialContext.java:351)
at org.apache.jsp.session_jsp._jspService(org.apache.jsp.session_jsp:69)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:81)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.jboss.web.tomcat.security.CustomPrincipalValve.invoke(CustomPrincipalValve.java:39)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:157)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:59)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112)
at java.lang.Thread.run(Thread.java:595)
I am sorry if the question is silly..... My Remote Interface will be one like this
import javax.ejb.Remote;
@Remote
public interface CityService {
public String getCity();
And My Bean Class will be
import javax.ejb.EJB;
import javax.ejb.Remote;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
@EJB
@Remote(CityService.class)
@Stateless(mappedName="ejb/CityService")
public class CityServiceBean implements CityService {
public String getCity(){
return "Chennai Metropolitan";
And the client which invokes the bean will be
InitialContext ctx = new InitialContext();
CityService c = (CityService)ctx.lookup("ejb/CityService");
System.out.println("Msg from Bean"+c.getCity());
please help me out of this issue....
Thanks in advance

ford wrote:
If you deploy your application in a .ear, you also can use this:
You have to set a name to your EJBBean -> @Stateless(name = "XXX")
The client for remote interface -> cxt.lookup(Name_of_your_own_ear_without_extension + "/XXX/Remote");
The client for local interface -> cxt.lookup(Name_of_your_own_ear_without_extension + "/XXX/Local");the problem with this approach is that if you version your ears, the version numbers show up in the jndi names, and your client code will be hard coded to specific server versions.

A question about entity manager in stateless session bean.

JSR 220 ejbcore, page 47 : stateless session bean: All business object references of the same interface type for the same stateless session bean have the "same object identity", which is assigned by the container.
So, if we have two session beans in client code...
@EJB Cart cart1;
@EJB Cart cart2;
then cart1.equals(cart2)==true
If we declare entity manager in stateless session bean:
@PersistenceContext( unitName="ds" ,type=PersistenceContextType.TRANSACTION)
private EntityManager em;If cart1 and cart2 are the same reference, do we have any problem when using the same reference(maybe the same em? ) to get data from db?

If cart1 and cart2 are the same reference, do we have
any problem when using the same reference(maybe the
same em? ) to get data from db?No. In EJB, there is a distinction between the EJB reference and the bean instance.
Each time you make an invocation on an EJB reference for a stateless session bean,
the container can choose any instance of that bean's bean class to process the
invocation. That's true whether you invoke the same reference multiple times or
two difference references to the same bean.
Each bean instance is guaranteed to be single-threaded.

How create EJB 2.1 Stateful Session Bean in a EJB 3.0 Session Bean

Hi All,
We have been developing on EJB 2.1. We are now adding a module on EJB 3.0.
How can we "create" a stateful session bean with create method signature similar to create(String id)?
We have tried
// this is the remote interface
@EJB AddressBean abean;
But not working
Any help will be appreciated.

There is no explicit create() call for EJB 3.0 session beans. It doesn't really matter though
since you can accomplish the same thing by defining your own business method to act
as an initializer for whatever state you'd like. E.g.
@Remote
public interface FooInterface {
public void initialize(String id);
// ... other business methods
@EJB FooInterface fooRef;
fooRef.initialize("foo");
--ken

EJB 2.1 session bean calling EJB 3 session bean?

I have a WL 10 (JDK 1.5/EE 5) server that has several EJB 3 stateless session beans deployed and working well. But now I need to allow a JBoss 3.2.3 (JDK 1.4) EJB 2.1 session bean make remote calls into these EJB 3 EJBs. Can this even work?
It seems to me that EJB 3 calling EJB 2 would be fine, but not in the reverse?

I have a WL 10 (JDK 1.5/EE 5) server that has several EJB 3 stateless session beans deployed and working well. But now I need to allow a JBoss 3.2.3 (JDK 1.4) EJB 2.1 session bean make remote calls into these EJB 3 EJBs. Can this even work?
It seems to me that EJB 3 calling EJB 2 would be fine, but not in the reverse?

Call stateless session bean EJB 2.0 from Webdynpro Java UI

Hello,
Can someone please tell me asto how to call a stateless session bean EJB 2.0 from Webdynpro Java UI?
The NWDS version is 7.0.
Thanks and Regards,
Arya

Hi Aryadipta
Please check this pdfs
https://www.sdn.sap.com/irj/scn/index?rid=/library/uuid/b00917dc-ead4-2910-3ebb-b0a63e49ef10&overridelayout=true
Steps for calling stateless session bean in Webdynpro java
Go to NWDS -> open perspective ->j2ee
select EJB Module Project ->create a project with name
Open the Project -->RC on ejb-jar.xml -> Select new --> EJB
Give name to EJB Bean (First letter should be in capital letters)
select the type of bean as Stateless session bean and give the package name to store that EJB bean.
After that Expand ejb-jar.xml and then select the <projectEJB>
Double click on this on method tab double click you will get business method where we will create the methods for business logic
Double click on projectEJB and then RC on bean tab and write required business logic in bean window as follows(based on requirement we will design a business logic).
After writing the business logic go to project -> rebuild
Till now we have created one EJB jar file
then go to File-->Enterprise Application Project -->create a project (projectEAR)
After creating a project click on next-> here we will have ear projects and then we select specific project required for our application.(here select projectEJB)
After that Calculate EAR project will be available on j2ee explorer.
Right click on <Bean> here
select New->Web Service->give a name to webservice and select Default configuration type as simple SOAP
-->click next -> Finish.
That webservice and related are created in ejb-jar.xml .
Expand the ejb-jar.xml.and double click on < webservice>
RC ProjectEJB -> Build EJB Archive RC on CalculateEAR ->Build applicationarchive.
Expand the projectEAR->RC on CalculateEAR.ear->Deploy to J2EE Engine
Double click on calculateEAR.ear ->Webservice navigator tab ->we eill servers expand the node
select the specific WebService
Here we test the webservice by click on Test and test it.
After that go to Web dynpro perspective ->create one webdynpro Project and one component
RC on model> Select import Web Service model(last)>give model name and package
and select radio button as local file system or URL
Go to WSnavigator->copy the WSDL path and paste it in model WSDL path and click on finish.
from here onwards steps are same as that adaptive RFC model
Hope it helps
Thanks
Tulasi Palnati
Edited by: Tulasi Palnati on Aug 26, 2009 12:15 PM
Edited by: Tulasi Palnati on Aug 26, 2009 12:43 PM

EJB Configuration (Stateless Session)

Hi,
It Looks like <stateless-session-descriptor> is optional in weblogic-ejb-jar.xml and so is <pool>. I deployed my stateless session bean in WLS 8.1 only with the following in the weblogic-ejb-jar.xml and without any info about min/max bean pool size:
=====================================
weblogic-ejb-jar>
<weblogic-enterprise-bean>
<ejb-name>MyOwnEjb</ejb-name>
<transaction-descriptor>
<trans-timeout-seconds>600</trans-timeout-seconds>
</transaction-descriptor>
<jndi-name>MyOwnEjb</jndi-name>
</weblogic-enterprise-bean>
</weblogic-ejb-jar>
======================================
If that is the case, what is the default set for
<initial-beans-in-free-pool> and <max-beans-in-free-pool>?
I am making many calls to this ejb and I suspect the default pool size must be greater than 1 otherwise I would expect one of my simultaneous EIB calls would have been failed.
Any idea what happens if you do not set these defaults for max/min-beans-in-free-pool ??
Thank you,

The default initial size is 0. I believe the default max pool size for a slsb is 1000. However, it's typically limited by the number of threads you run in the server.
You generally don't need to tune these for a slsb. Also, imho 600 seconds is too long for a transaction timeout.
-- Rob
WLS Blog http://dev2dev.bea.com/blog/rwoollen/

Some methods not working in EJB 3.0 stateless session bean

Hi,
I am trying to build an application with EJB 3.0 stateless session bean in weblogic 10. In that during build (using ant 1.6) it showing error as one of the ejb-class should have anotataion as @stateless, @stateful or @messageDiven
But i have given it corrrectly.
When I comment some of the methods the same bean is working fine. While i have annoatated some of the methods with @transaction attribute annotataion.
So, should i write all those methods there any particular order or what.
Can anybody pls tell me, what can be the problem as weblogic.appc is giving such error?

Hi,
I am trying to build an application with EJB 3.0 stateless session bean in weblogic 10. In that during build (using ant 1.6) it showing error as one of the ejb-class should have anotataion as @stateless, @stateful or @messageDiven
But i have given it corrrectly.
When I comment some of the methods the same bean is working fine. While i have annoatated some of the methods with @transaction attribute annotataion.
So, should i write all those methods there any particular order or what.
Can anybody pls tell me, what can be the problem as weblogic.appc is giving such error?

Stateless Session Bean + EJB Question + Jboss

Hello,
If I have a stateless session bean on a linux machine and it works locally what do i need to do to access a method in the session bean from a remote windows machine.
I would like to be able to execute my client jar file on a windows machine and have it access the jboss server on the linux machine. what do i need to do?
i have the session bean working locally on both windows and linux machine. do i need to to have a JSP/Servlet to access the session bean? can the session bean not be accessed directly? what should my classpath look like? do I need to include extra jar files in my client jar file.?
Thanks,
Joyce

Thanks guys for the help but I am still a little lost.
My Client windows machine has the client jar file and all the other jar files. This is my client class
package helloworld.client;
import javax.naming.Context;
import javax.naming.InitialContext;
import java.util.Hashtable;
import java.util.Properties;
import helloworld.interfaces.HelloWorldHome;
import helloworld.interfaces.HelloWorld;
public class HelloClient
     public static void main(String[] args)
          Hashtable prop = new Hashtable();
          prop.put ("java.naming.factory.url.pkgs","org.jboss.naming:org.jnp.interfaces");
          prop.put ("java.naming.provider.url","jnp://172.16.220.160:1099");
          prop.put ("java.naming.factory.initial","org.jnp.interfaces.NamingContextFactory");
          try
               Context ctx = new InitialContext(prop);
               Object obj = ctx.lookup("ejb/helloworld/HelloWorld");
               System.out.println(obj);
               HelloWorldHome home = (HelloWorldHome)javax.rmi.PortableRemoteObject.narrow(obj, HelloWorldHome.class);
               HelloWorld helloWorld = home.create();
               String str = helloWorld.sayHelloEJB("JOYCE is COOL");
               System.out.println(str);
               helloWorld.remove();
          catch(Exception e)
               e.printStackTrace();
I get a NullPointer ie the home object is null. The IP address is the IP of the Linux machine that has Jboss running on.
Questions are:
1. Do I need to have Tomcat running on my client machine if I am to connect via HTTP? Does this alter my client code.?
2. My JNDI lookup is what is causing the problem. Does my jboss.xml and my ejb-jar.jar look okay to you.
jboss.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE jboss PUBLIC "-//JBoss//DTD JBOSS//EN" "http://www.jboss.org/j2ee/dtd/jboss.dtd">
<jboss>
<enterprise-beans>
<session>
<ejb-name>helloworld/HelloWorld</ejb-name>
<jndi-name>ejb/helloworld/HelloWorld</jndi-name>
</session>
</enterprise-beans>
<resource-managers>
</resource-managers>
</jboss>
ejb-jar.jar
<?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>No Description.</description>
<display-name>Generated by XDoclet</display-name>
<enterprise-beans>

<session >
<description><![CDATA[No Description.]]></description>
<ejb-name>helloworld/HelloWorld</ejb-name>
<home>helloworld.interfaces.HelloWorldHome</home>
<remote>helloworld.interfaces.HelloWorld</remote>
<ejb-class>helloworld.session.HelloWorldBean</ejb-class>
<session-type>Stateless</session-type>
<transaction-type>Bean</transaction-type>
</session>





</enterprise-beans>


<assembly-descriptor >



</assembly-descriptor>
</ejb-jar>
Do I need RMI ? Do I need to concern myself with CORBA? All Im looking for is a step by step to understanding what I need to configure? Is their some way I can debug?
Thanks alot,
Joyce

A tough one for EJB experts - Stateless session bean spec question

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