ClassCastException EJB home

Hi,
first of all sorry for my english...
I have a standalone Tomcat with a JAAS login module that should call
an ejb deployed on JBoss.
If i make
Context context = new InitialContext(props);
Object ref= context.lookup("LoginManagerEJB");
LoginManagerHome home = (LoginManagerHome)PortableRemoteObject.narrow(ref, LoginManagerHome.class);
LoginManager loginManager = home.create();
i get
java.lang.ClassCastException
at com.sun.corba.se.internal.javax.rmi.PortableRemoteObject.narrow(PortableRemoteObject.java:293)
at javax.rmi.PortableRemoteObject.narrow(PortableRemoteObject.java:134)
Instead if i make
Context context = new InitialContext(props);
Object ref= context.lookup("LoginManagerEJB");
ClassLoader loader = ref.getClass().getClassLoader();
Class loginManagerHomeClass = loader.loadClass("it.***.***.model.ejb.login.LoginManagerHome");
LoginManagerHome home = (LoginManagerHome)PortableRemoteObject.narrow(ref, loginManagerHomeClass);LoginManager loginManager = home.create();
i get
java.lang.ClassCastException: $Proxy0 cannot be cast to it.***.***.model.ejb.login.LoginManagerHome
Can anyone explain me where i make som error or if the thing is impossible?
Thanks

Similar Messages

Can l make an instance of EJB home handler / Datasource shared by EJB objs

all ejb guru
As far as l know, it is general rule of thumb to cache the EJB home handlers and datasource object at EJB bean instance. But can l go a step further, make the same instance of EJB home handlers and datasource object shared by more than 1 EJB bean instance ?
( l checked out the methods of javax.ejb.EJBhome and javax.sql.DataSource. They are not declared as synchronized. It seems to me that EJB home handlers and datasource object are not thread safe and not suitable for being shared. Even they are thread-safe, if they are shared by 1+ EJB bean instance. Sharing EJB home handlers and datasource object may interfere the thread management of EJB container. Am l correct ? )
It is highly appreciated someone can share with me your insight in this issue.
thanks & regards
Danny

Okay, you got me there. However, it's usually a better practice to start a new thread with your specific question instead of resurrecting old threads that (obviously) nobody cared enough to answer.
DataSources are retrieved from the container via JNDI. You may (generally) cache them in order to alleviate the JNDI lookup without worrying about Threads, as there is only (usually) one DataSource object per server (or node in a cluster). Do not cache (in your code) the Connection objects obtained from the DataSource - always close them in order to return them to the pool maintained by the DataSource.
Caching EJB HomeHandles is the accepted manner of avoiding repeated JNDI calls to locate EJBs. Typically, extracting the EJBHome from the HomeHandle re-initializes whatever network operations are embedded in the EJBHome object(s) by the vendor's implementation. Once again, you do not necessarily need to worry about Threads - the container and vendor implementation is already taking care of that for you, transparently.
Think about it: if there were Threading issues, even retrieving the above objects via JNDI would ensure that J2EE application servers wouldn't be Thread safe and all operations would be, essentially, blocked each time. Obviously, this is not the case since both DataSources and EJBHome objects can have multiple clients using them simultaneously. Just because there's not explicit synchronized tag on any of the methods defined in these interfaces doesn't mean they're single-Thread objects.

EJB home stubs in a cluster

The following URL describes how replica-aware EJB home stubs work. Basically,
when you do a lookup for the EJB home in JNDI, you get a home stub on any of the
nodes in the cluster.
However, I want to invoke EJBs on a particular node in the cluster. Can I do
this by simply disabling the replica-aware EJB home in the deployment descriptor
and doing a remote JNDI lookup on the desired node in the cluster? And if so,
would I have to bind each EJB's home to JNDI with a different name?
-reza
http://edocs.bea.com/wls/docs61/cluster/object.html#1006777
All bean homes can be clustered. When a bean is deployed on a server, its home
is bound into the cluster-wide naming service.
Because homes can be clustered, each server can bind an instance of the home under
the same name. When a client looks up this home, it gets a replica-aware stub
that has a reference to the home on each server that deployed the bean. When create()
or find() is called, the replica-aware stub routes the call to one of the replicas.
The home replica receives the find() results or creates an instance of the bean
on this server.

However, I want to invoke EJBs on a particular node in the cluster. Can Ido
this by simply disabling the replica-aware EJB home in the deploymentdescriptor
and doing a remote JNDI lookup on the desired node in the cluster? Andif so,
would I have to bind each EJB's home to JNDI with a different name?Yes. Something like that. We do that with JMS queues sometimes (to send a
message to a particular machine in the cluster).
Peace,
Cameron Purdy
Tangosol, Inc.
Clustering Weblogic? You're either using Coherence, or you should be!
Download a Tangosol Coherence eval today at http://www.tangosol.com/
"Behforooz" <[email protected]> wrote in message
news:3c8fc8bf$[email protected]..
>

ClassNotFound while narrowing JNDI ref to ejb home interface

Hello everybody
I'm quite new to BEA WebLogic. I deployed Jasmine application on Bea WLS7 (example
app from Mastering EJB 2). But when i tried to use login servlet, it threw an
exception ClassNotFound when narrowing ejb home interface (obtained via JNDI).
EJBs are in .jar file, and web files are in the .war file, maybe this is the problem.
Should I copy ejb classes to .war file, or make some tricks with CLASSPATH, or
maybe there is better way to make it work (maybe via J2EE references or something
like this).
Thanks in advance

Strange. And you do not have any application classes in the system
classpath?
Konrad R. <[email protected]> wrote:
"Dimitri I. Rakitine" <[email protected]> wrote:
Did you deploy ejbs and war in the same ear?
Yes, both were packed up into one .ear archive>>
Konrad R. <[email protected]> wrote:
Hello everybody
I'm quite new to BEA WebLogic. I deployed Jasmine application on BeaWLS7 (example
app from Mastering EJB 2). But when i tried to use login servlet, itthrew an
exception ClassNotFound when narrowing ejb home interface (obtainedvia JNDI).
EJBs are in .jar file, and web files are in the .war file, maybe thisis the problem.
Should I copy ejb classes to .war file, or make some tricks with CLASSPATH,or
maybe there is better way to make it work (maybe via J2EE referencesor something
like this).
Thanks in advance--
Dimitri

EJB Home Objects and Stubs

Hi,
Can anyone pls tell me,what are the objects are created in Server after the Deployment of EJB.
Is the EJB Home Object,EJB Home Object Stub,EJB Home Object Skeleton, EJB Local Home Object, EJB LocalHome Object Stub,Ejb LocalHome Object Skeleton.And Finally both the Stub objects and Skeleton Objects will be stored in the Jndi Registry ?
Thanks in Advance,
Venkat

Nic,
Caching the home object is a comon practice.
Take a look here:
http://www.theserverside.com/resources/patterns_review.jsp
Look at the EJB Home Factory Pattern.
Regards,
-Dat

Unable to bind EJB Home Interface to the JNDI name

Why do I get this error?? What is the jndi-name in weblogic-ejb-jar.xml
Unable to deploy EJB: OrganizationEJB from sempire_bc.jar:
Unable to bind EJB Home Interface to the JNDI name:
com.sempire.builder.business
_component.Organization. The error was:
javax.naming.NameAlreadyBoundException: Organization is already bound;
remaining
name 'com.sempire.builder.business_component'
<<no stack trace available>>

Slava,
In case I change the name of the jndi name to a unique name. I still get the same
problem. I checked for multiple occurences, but there aren't any.
My web.xml file is:
<ejb-local-ref>
<description>
Reference EJB resources in Weblogic Resources
</description>
<ejb-ref-name>GangsterEJB</ejb-ref-name>
<ejb-ref-type>Entity</ejb-ref-type>
<local-home>com.sempire.builder.business_component.GangsterHome</local-home>
<local>com.sempire.builder.business_component.Gangster</local>
</ejb-local-ref>
My weblogic-ejb-jar.xml file is:
<weblogic-enterprise-bean>
<ejb-name>GangsterEJB</ejb-name>
<entity-descriptor>
<persistence>
<persistence-type>
<type-identifier>WebLogic_CMP_RDBMS</type-identifier>
<type-version>6.0</type-version>
<type-storage>META-INF/weblogic-cmp-rdbms-jar.xml</type-storage>
</persistence-type>
<persistence-use>
<type-identifier>WebLogic_CMP_RDBMS</type-identifier>
<type-version>6.0</type-version>
</persistence-use>
</persistence>
</entity-descriptor>
<reference-descriptor>
<resource-description>
<res-ref-name>jdbc/GangsterDB</res-ref-name>
<jndi-name>oraclePool</jndi-name>
</resource-description>
</reference-descriptor>
<local-jndi-name>Gangster_test</local-jndi-name>
</weblogic-enterprise-bean>
I do not get the problem.
Thank you
Ronak Parekh
"Slava Imeshev" <[email protected]> wrote:
Hi Ronak,
This exception means that you already have a bean
with the same JNDI name. Search your weblogic-ejb-jar.xml files
for multiple occurrences of the name and fix the problem.
Regards,
Slava Imeshev
"Ronak Parekh" <[email protected]> wrote in message
news:[email protected]...
Why do I get this error?? What is the jndi-name in weblogic-ejb-jar.xml
Unable to deploy EJB: OrganizationEJB from sempire_bc.jar:
Unable to bind EJB Home Interface to the JNDI name:
com.sempire.builder.business
_component.Organization. The error was:
javax.naming.NameAlreadyBoundException: Organization is already bound;
remaining
name 'com.sempire.builder.business_component'
<<no stack trace available>>

Undable to bind EJB Home during deploy

Hi
I'm getting an exception when I redeploy to weblogic81. I have and ear with several ejb jars in it. The following is the message I get...
Unable to bind EJB Home Interface to the JNDI name: EJBTestService. javax.naming.NameAlreadyBoundException: EJBTestService is already bound; remaining name :at weblogic.jndi.internal.BasicNamingNode.bindHere(BasicNamingNode.java:333) at weblogic.jndi.internal.ServerNamingNode.bindHere(ServerNamingNode.java:124) at weblogic.jndi.internal.BasicNamingNode.bind(BasicNamingNode.java:291) at weblogic.jndi.internal.WLEventContextImpl.bind(WLEventContextImpl.java:279) at weblogic.jndi.internal.WLContextImpl.bind(WLContextImpl.java:384) at weblogic.ejb20.deployer.ClientDrivenBeanInfoImpl.activate(ClientDrivenBeanInfoImpl.java:1116) at weblogic.ejb20.deployer.EJBDeployer.activate(EJBDeployer.java:1362) at weblogic.ejb20.deployer.EJBModule.activate(EJBModule.java:631)
This error doesn't always occur with the same jar in the ear. Sometimes the above jar prepares and activates fine and another one fails.
If anyone has any idea I'd appreciate feedback.

Hello,
The error suggests that an object is already bound to the JNDI name.
This can happen if you have 2 or more ejbs in your EAR file wit the same JNDI name or if your application has not fully/cleanly undeployed before you try to redeploy it.
I suspect the latter is your problem. Once you have undeployed your application use the weblogic console to view your JNDI tree and make sure nothing is bound that should not be bound. Then redeploy your app. If you still have the problem check your ear does not have duplicate ejbs or ejbs using the same JNDI name.

EJB Home Factory question

I have a doubt about implementing EJB Home Factory design pattern ( a form of Service Locator pattern)
in an application running on Weblogic clustered environment. A colleague of mine told me that because this pattern is singleton based( which is true - no doubt about that), it will not be supported by the container
beacause server instances are being run on different JVMs. I think what he says is wrong but want to be sure. Please tell me if it is OK to implement this pattern in this type of environment and if yes/no, why.
Thanks
Vlad

Yes, you can implement it, but your colleague is correct: it won't work quite the way you think it will.
A "Singleton" in the WLS server (we'll get to clusters in a minute) is only unique inside it's ClassLoader (not JVM). The way WLS works is that it allocates/creates ClassLoaders for each major type of deployment: EAR, EJB, and WAR. Fortunately, they are "nested" (in the order given), so if you have a SIngleton in the EAR ClassLoader, it will be the only instance of that class for the EJBs and WARs in that EAR. SImilarly, if you've deployed only a WAR, the Singleton will only be unique for that WAR, not the entire server.
With clusters, WLS is not "aware" of the Singleton as it is not a distributed object. So the instance(s) will not propagate between the nodes. So if you've deployed an EAR with a Singleton, the number of Singletons in the system will be n, where n is the number of nodes. If you have the same Singleton class in two different EARs, then it's obvious that there will be 2*n instances of the Singleton.
Now, given the pitfalls and caveats, yes, it is an effective pattern to reduce the number of JNDI lookups and caching of the HomeHandle implementations for EJBs.

Problem in looking up EJB Home

Hi,
I am a starter to EJB's.. I am trying to run the "ConverterApp" application from the Sun's J2EE tutorial bundle. When I run the program thru the J2EE application client, I dont get any errors and I get the desired output. But when I use the Web client(index.jsp) then I get an "Internal Server Error" and it gives me an "Null pointer exception".
At the command prompt it says: "Unable to lookup home: TheConverter No object bound to name java:comp/env/ejb/TheConverter
I would greatly appreciate it if somebody could tell me what the problem is.
Thanks
prasanna

Hi Kumar,
Thanks for your help.. I had given the wrong slash "\" while typing the full path name. figured it out...
thanks
prasanna

How to compile ejb home class?

hi, recently i download a program and compile in native machine , and some error happened.The home class is :
import javax.ejb.EJBObject;
import java.rmi.RemoteException;
public interface Converter extends EJBObject {
public double dollarToYen(double dollars) throws
RemoteException;
public double yenToEuro(double yen) throws RemoteException;
when I compile this program, the jvm notice that the javax.ejb can not find. I have set class_path which like this:
class_path=.;..;c:\jdk1.3\lib;c:\jdkee1.3\lib;
Is there any one who so kind to help me ? Thanks at advance.

Uh, that class path should be:
classpath=.;..;c:\jdkee1.3\lib\j2ee.jar;
If you specify a directory, Java will search for class files in that directory; if you specify an archive (zip or jar) Java will search for class files in the archive. The class files you need reside in the two archives c:\jdk1.3\lib\rt.jar and c:\jdkee1.3\lib\j2ee.jar. rt.jar is normally decided (and automatically included in the class path) by the JVM you are running, so better leave it out.

Casting error when trying to retrieve an EJB home interface from a servlet

          I am trying to call a method on a session bean from a servlet. I am receiving a Class Cast exception when trying to use the narrow method. I have this code working from an external java client. Is there something specific I have to do?


Hi
          You must check the following rules :
          1) In JAR Files ( of your EJB ) check if there are remote mehods that return
          any class that is already used in servlets
          This classes must be remove from the servlet package ( if you are using WAR
          files ).
          2) Please read the BEA WebLogic Enterprise Java Beans Manual about the class
          loader and related problemas such as ClassCastException and
          ClassNotFoundException.
          Good Luck !
          Steve Schaber <[email protected]> escribió en el mensaje de noticias
          39ee4996$[email protected]..
          >
          > I am trying to call a method on a session bean from a servlet. I am
          receiving a Class Cast exception when trying to use the narrow method. I
          have this code working from an external java client. Is there something
          specific I have to do?
          >

How do you bind a EJB home to a COSNaming service ?

Hi All,
I am trying to have a corba client(written in java) communicate to an EJB,
but I am facing a few problems. As per the procedure specified by the BEA documentation
I have created the idl files. Then using the idl (idl -jpoa=. -jbase=. Hello.idl)
command I have created the respective java classes. But I am not sure wether
the Weblogic server by default binds the EJB to a COSNaming service or not(In
Borland App server it binds to a COSNaming service). Incase it does not then what
do I need to do, to have the EJB bound to a COSNaming service. Generally how do
I find out wether a Home Interface is bound to a Naming service? I am using Weblogic6.1
app server and IONA Orbix 2000.
Regards,
Ameet.

Hello Andy,
Thank you very much for your reply. Forgive me sending out several
messages, just to try to reach you. You can tell how frustrated I am
with the issue. The O2K version I tried is 2.0 came with E2A application
server.
Have you tried Orbix 3? and any luck of it? What do you think is
the effective way to push IONA to fix the bug?
Thanks,
Qing
Andy Piper <[email protected]> wrote:
"Qing Lu" <[email protected]> writes:
Yeah, this is a bug in the Orbix 2000 idl compiler, I ran into this
when I tried it and couldn't find any workaround. I reported the
problem to Iona but I don't know whether they did anything about
it. Incidentally what version of O2K is this? I tried with 1.2 and was
going to try 2.0 - but if this is with 2.0 I won't bother.
andy
As far as I know, BEA implemented COSNaming wrapper around their JNDI.So EJB
got bound just like in the normal case and your client uses COSNamingto get
reference.
Do you have any experience with CORBA C++ client (Orbix 2000) callingEJB? I have
problem with it. I can generate stub files with Orbix idl compiler.
But when I link stubs with the client.cpp, I got the following:
[exec] clientC.cpp
[exec] client.hh(1008) : error C2327: 'IT_Gen_DynamicProxy_EJBHome::EJBHome
::EJBMetaData' : member from enclosing class is not a type name, static,or enum
erator
[exec] clientC.cpp(1785) : error C2065: 'itlocal_result' : undeclaredident
ifier
[exec] clientC.cpp(1785) : error C2296: '*' : illegal, left operandhas typ
e 'class javax::ejb::EJBMetaData *(__thiscall javax::ejb::IT_Gen_DynamicProxy_EJ
BHome::*)(void)'
[exec] clientC.cpp(1789) : error C2440: '=' : cannot convert from'class
ja
vax::ejb::EJBMetaData *' to 'int'
[exec] This conversion requires a reinterpret_cast, aC-style cast
or function-style cast
[exec] client.cpp
[exec] client.hh(1008) : error C2327: 'IT_Gen_DynamicProxy_EJBHome::EJBHome
::EJBMetaData' : member from enclosing class is not a type name, static,or enum
erator
[exec] Generating Code...
BUILD FAILED
Any help will be appreciated.
"Ameet Kanguri" <[email protected]> wrote:
Hi All,
I am trying to have a corba client(written in java) communicate
to
an EJB,
but I am facing a few problems. As per the procedure specified bythe
BEA documentation
I have created the idl files. Then using the idl (idl -jpoa=. -jbase=.
Hello.idl)
command I have created the respective java classes. But I am notsure
wether
the Weblogic server by default binds the EJB to a COSNaming serviceor
not(In
Borland App server it binds to a COSNaming service). Incase it doesnot
then what
do I need to do, to have the EJB bound to a COSNaming service. Generally
how do
I find out wether a Home Interface is bound to a Naming service? Iam
using Weblogic6.1
app server and IONA Orbix 2000.
Regards,
Ameet.--

How to use JNDI to lookup remote EJB Home?

Hello,
I am writing a servlet to call a remote EJB on another machine.
I use JNDI to lookup remote EJBHome (not) but fail.
Any advice?
Any trick to configure application-client.xml?
Thanks!

Use com.evermind.server.rmi.RMIInitialContextFactory instead
Here an example
// EmployeeClient.java
package mypackage5;
import javax.ejb.*;
import javax.naming.*;
import javax.rmi.PortableRemoteObject;
import java.io.*;
import java.util.*;
import java.rmi.RemoteException;
import com.evermind.server.ApplicationClientInitialContextFactory;
import com.evermind.server.rmi.RMIInitialContextFactory;
* A simple client for accessing an EJB.
public class EmployeeClient
public static void main(String[] args)
System.out.println("EmployeeClient.main(): client started...");
try
* initialize JNDI context by setting factory, url and credential
* in a hashtable
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, "com.evermind.server.rmi.RMIInitialContextFactory");
//env.put(Context.INITIAL_CONTEXT_FACTORY, "com.evermind.server.ApplicationClientInitialContextFactory");
env.put(Context.PROVIDER_URL, "ormi://koushikm:23791/application4");
env.put(Context.SECURITY_PRINCIPAL, "admin");
env.put(Context.SECURITY_CREDENTIALS, "admin");
* or set these properties in jndi.properties
* or use container defaults if that's where client got launched from
Context context = new InitialContext(env);
* Lookup the EmployeeHome object. The reference is retrieved from the
* application-local context (java:comp/env). The variable is
* specified in the assembly descriptor (META-INF/application-client.xml).
Object homeObject =
context.lookup("HelloEJB");
System.out.println("EmployeeClient.main(): bean found...");
// Narrow the reference to EmployeeHome.
HelloEJBHome home =
(HelloEJBHome) PortableRemoteObject.narrow(homeObject,
HelloEJBHome.class);
System.out.println("EmployeeClient.main(): home narrowed...");
// Create remote object and narrow the reference to Employee.
HelloEJB remote =
(HelloEJB) PortableRemoteObject.narrow(home.create(), HelloEJB.class);
System.out.println("EmployeeClient.main(): remote created...");
String message=remote.helloWorld("SUCCESS");
System.out.println(message);
} catch(NumberFormatException e) {
System.err.println("NumberFormatException: " + e.getMessage());
} catch(RemoteException e) {
System.err.println("RemoteException: " + e.getMessage());
} catch(IOException e) {
System.err.println("IOException: " + e.getMessage());
} catch(NamingException e) {
System.err.println("NamingException: " + e.getMessage());
} catch(CreateException e) {
System.err.println("CreateException: " + e.getMessage());
Hello,
I am writing a servlet to call a remote EJB on another machine.
I use JNDI to lookup remote EJBHome (not) but fail.
Any advice?
Any trick to configure application-client.xml?
Thanks!

Problem in compiling ejb home interface

i am starting work on ejbs .the first thing i want to know is how to find an ejb api.I have searched the whole of java site but without success.
can anyone help me start on with ejbs.
Thank you.

there is book on the web, the author name is ed roman, it is free on the web, search in the search engine. www.google.com. this book will definitely help you
kiran

Unable to find Local Ejb home in websphere 6.0

Its really anoying as am unable to guess . I am invoking an EJB locally using code as below . The Ejb works fine while testing with UniversalTestClient However when i try to invoke it from my Client it gives jndi error.
Am using RAD 6.0 IDE and WebSphere6.0 and Ejb 2.1
I tried calling ejb providing different jndi names as below but it doesn't work .
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, "com.ibm.websphere.naming.WsnInitialContextFactory");
env.put (Context.PROVIDER_URL, "corbaloc:iiop:localhost:2809/");
try{
InitialContext icontext = new InitialContext(env);
// Object result = icontext.lookup("local:ejb/DefaultSession");
// Object result = icontext.lookup("D7VRC491Node01Cell/nodes/D7VRC491Node01/servers/server1/TestEj b/ejb/com/test/ejbs/DefaultSessionLocalHome");
// Object result = icontext.lookup("local:ejb/ejb/com/test/ejbs/DefaultSessionLocalHome");
Object result = icontext.lookup("ejb/com/dhsmv/ejbs/DefaultSessionLocalHome");
DefaultSessionLocalHome localHome = (DefaultSessionLocalHome) result;
DefaultSessionLocal localSession = (DefaultSessionLocal) localHome.create();
String strTest = localSession.welcome(" Hello World ");
System.out.println(" Retrieved ejb method ..." + strTest);
I get an exception that first component of jndi name is not available. Please suggets where is the problem hiding. Is there any thing wrong with jndi name .
Thanks.

The CORBA error could suggest your bootstrap port is already being used by another process. Try changing it to something else.
Assuming your webconsole works - its something like this (although off the top of my head can't be sure...)
Select servers from the menu on the left, then select, your server.
From the newly loaded page, on the right hand side, you should see a link called "Ports". Modify your bootstrap port, usual value is 2809.
How does that work?

ClassCastException EJB home

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