Can EJB method return another EJB?

Hello,
I am new to EJB technology. I am working with Sun Application Server bundled in Netbeans 4.1
Is it po[b]ssible a method of a session bean to return another EJB which is instantiated with arguments depended on the method?
If no, is there an alternative way?
thank you in advance, Kostas

Is it possible within the SessionBean method to
call another Session Bean, create it using the
local interface, pass some parameters using setter
methods, then cast it from local interface to
remote and send it to the user?I think it's not possible casing Local Interface into Remote Intrface, because they inherit from different classes.
Remote interface extends EJBObject and Local interface extends EJBLocalObject
Fil

Similar Messages

EJB method returns 2D String array

Hi,
one of EJB method returns a 2 dimensional array of String. Is it okay? Is this a good EJB programming practice?
Thanks
Sabir

Its ok. but not consdered as best practice now.
Check out the DTO pattern(previously called value obects from sun's site.
--Ashwani

Can a method return a class ?

hi,
i have a simple question.
can a method return class value ?
in the below script i did'nt understand the commented line.
package com.google.gwt.sample.stockwatcher.client;
import com.google.gwt.user.client.rpc.RemoteService;
import com.google.gwt.user.client.rpc.RemoteServiceRelativePath;
@RemoteServiceRelativePath("login")
public interface LoginService extends RemoteService {
public LoginInfo login(String requestUri); //What is this ? is this a sample of what i asked ?
}

The answer to your question is yes.
The idea is that an object calls a function of another object (passing in objects to the function as arguments) in which that object returns an object (note the arguments or returned value of the function may alternately be primitive types). Each object typically encapsulates data and provides a rich set of functions to the calling object so that calling object doesn't have to deal with the raw data directly. Therefore, not only does the calling object get the data it wants, but also a rich set of functions that can manipulate that data.
Example:
Book book = new Book();
int characterCount = book.getChapter(3).getParagraph(4).getSentence(12).getWord(8).getCharacterCount();
In the above, each object (Book, Chapter,Paragraph,Sentence,Word) has a rich set of functions it provides to its caller.
Example: the Sentence Object has a collection of word objects (raw data). Functions it provides to Paragraph object are:
Word getWord(int index), Words getWords(), int getWordCount().
If you haven't already done so, I suggest reading a book on Java from cover to cover to pick up such Object Oriented concepts.

Can a method return multiple items

Can a method return more than one thing?
I want to have a method return a boolean and a String. My method is saying if something is right or wrong, then its saying the reason why.
help, please.
Thanx

Afternoon_Delight wrote:
My question is:
Is there a way so that it can be more like this:
public boolean, String checkValidity (){
To expand on the previous posts, one way (not saying it's the best one!) is to create an object that combines the information that you want returned:
public class MyValid
private boolean valid;
private String text;
public MyValid(boolean valid, String text)
    this.valid = valid;
    this.text = text;
public boolean isValid()
    return valid;
public String getText()
    return text;
class DoFoo
public MyValid checkValidity()
    return new MyValid(false, "Because I said so!");
}

Can an EJB method return processing results to its calling program?

Hi there,
I have an EJB method which does JDBC connection to a UDB. I want the ResultSet to be returned to JSP so I can format them in the page itself. I got an ClassCastException at the return statement. Could anybody point out what I might be missing?
Thanks a lot.
Andy

Here is the code related:
          try
               Context jndi = AuditPublicService.getContext();
               Object obj = jndi.lookup(AuditInterface.ALIAS);
               AuditHome auditHome =
                    (AuditHome) PortableRemoteObject.narrow(obj, AuditHome.class);
               Audit audit = auditHome.create();
                    this.rs = (ResultSet) audit.read();
          catch (Throwable t)
               System.out.println("Test.read():failed." + t.toString());
               t.printStackTrace();
and this is what I got:
Test.read():failed.java.lang.ClassCastException
java.lang.ClassCastException
P.S. When I track down to the return statement(return rs) in the audit.read(), I can see that the rs is exactly what I want, but failed when the EJB stub tries to cast it to Serializable. I tried to implements java.io.Serializable in both the calling class and the EJB. it didn't work.

EJB lookup from another EJB server

Hi people,
I have two application servers on two different computers. One
of them contains an EJB, which I need to access from another EJB
server. I know that I can achieve this using RMI, but will then
security and transaction contexts be propagated to the called
EJB?
Sincerely,
Sergei Batiuk.

Here is the solution posted on another forum:
[email protected] Dec 8, 6:03 am show options
Newsgroups: ibm.software.websphere.studio
From: [email protected]
Date: 8 Dec 2004 06:03:04 -0800
Local: Wed, Dec 8 2004 6:03 am
Subject: Re: EJB lookup on from one server to another does not work
Eric,
I dealt with this same problem trying to run 2 local servers (websphere
test servers), using 2 separate WSAD 5.1.2 workspaces. Running on 1
server I have an application that contains an EJB, and running on the
other server is an application that uses an access bean to make a
remote call to my EJB, running on my other server. I too repeately
received the "NameNotFoundException" when trying to lookup my EJB home
reference.
What you have to do to get around this is to modify the server
configuration of the application that contains the EJB that you are
attempting to call remotely. You must open the the server.wsi file for
the server that is running the EJB and go to the "Configuration" tab.
You must check the "Enable administrative console". Once this is
complete, start your server. When it is started, right click on the
server, and select "run administrative console". In the admin console,
select
servers -> application servers -> <your server> -> end points ->
bootstrap address. For "host" you must change "localhost" to either
your ip address or computer name (ive only tried my ip, but your
computer name should work too). When building your properties to get
the initial context, make sure you use
"env.put(Context.PROVIDER_URL, "corbaloc:iiop:<the ip or computer name
listed as the bootstrap host of server running ejb>:<the port listed as
the bootstrap port of server running ejb, which is 2809 in your case>
Restart your server and things should work.

Can "main" method return values

Hi,
I have a requirement of returning values to the
command prompt from the main method. Is this possible
to do in the first place. Is it valid.
i.e. Can you do the following in Java,
=======================================
import java.io.*;
import java.lang.Object;
import java.util.*;
public class P
     public static String main(String args[])
     String bye = "BYE";
     return(bye);
=========================================
Can "main" method in Java return values at command
prompt.
Can you have something like,
public static String main(String args[])
instead of
public static void main(String args[])
Help urgently needed as I need to pipe data from a
Java program to a C++ program. One method is to
writing to a flat file but this would cause overheads
reading and writing to a file, hence this way.
Any help would be greatly appreciated.
Thanks in advance.
Thank,s

Hi jchak,
Yes I am trying to pass a Java String to a C++
application. Any insights, any help.
OK the whole thing goes as follows,
=========================================
Theres a C++ application which first starts up.
This app is then supposed to invoke a Java class file
which does some processing. Finally the value of one
variable in Java (actually a huge String) is to be made
available back to C++. This could be done thru flat file
wherein the Java outputs the string to the flat file
and on return the C++ program can be made to read the
same flat file to retrieve that string but this would
surely cause some overheads (time factor) reading and
writing files. So I wish to devise some way by means
of which I can return the string value back to the C++
program. Piping of data from one app to another is what I
want to do.
Is there some way by means of which Java can return
back or communicate or pipe back the string back to
C++. How can it be done without using external flat files
or databases.
Thansk,
JAtin

Bug? EJB method Return Value and Client Catch the Exception?

oc4j 9.0.3 on the windows 2000
I write a Stateless Session Bean named SB1 ,
and define application exception.
The Code as follow:
public class AppErrorException extends Exception
public interface SB1 extends EJBObject
public String getMemono(String sysID, String rptKind, String parentMemono)
throws RemoteException, AppErrorException;
public class SB1Bean implements SessionBean
public String getMemono(String sysID, String rptKind, String parentMemono)
throws RemoteException, AppErrorException
throw new AppErrorException("Error in getMemono");
public class SB1TestClient
try
memomo= sb1.getMemono(.....);
catch(AppErrorException ae)
ae.printStackTrace();
I found a bug.
If SB1.getMemono() throws the AppErrorException, but SB1TestClient will not catch any Exception.
It is not normal!!!!
[cf]
But If I convert "public String getMemono(...)" into "public void getMemono(...)",
When SB1.getMemono() throws the AppErrorException, but SB1TestClient will catch any Exception.
It is normal.

getMemono(.......)'s code as follow:
public String getMemono(String sysID, String rptKind, String parentMemono)
throws AppErrorException
log("getMemono("+sysID+", "+rptKind+", "+parentMemono+")");
Connection connection= null;
CallableStatement statement = null;
String memono= "";
short retCode= -1;
String retMsg= "";
try
String sql= this.CALL_SPGETMEMONO;
connection = ResourceAssistant.getDBConnectionLocal("awmsDS");
statement= connection.prepareCall(sql);
statement.setString(1, sysID.trim());
statement.setString(2, rptKind.trim());
statement.setString(3, parentMemono.trim());
statement.registerOutParameter(4, java.sql.Types.VARCHAR);
statement.registerOutParameter(5, java.sql.Types.SMALLINT);
statement.registerOutParameter(6, java.sql.Types.VARCHAR);
statement.executeQuery();
retCode= statement.getShort(5);
retMsg= statement.getString(6);
log("retCode="+retCode);
log("retMsg="+retMsg);
if (retCode==AppConfig.SHORT_SP_RETCODE_FAILED)
log("retCode==AppConfig.SHORT_SP_RETCODE_FAILED");
this.sessionContext.setRollbackOnly();
throw new AppErrorException(retMsg);
memono= statement.getString(4);
log("memono="+memono);
if (rptKind.trim().length()<6)
log("rptKind.trim().length()<6");
this.sessionContext.setRollbackOnly();
throw new AppErrorException("rptKind.trim().length()<6");
memono= "SS";
catch (AppErrorException ae)
log("catch(AppErrorException ae)");
throw ae;
//throw new EJBException(ae.getErrMsg());
catch (Exception e)
log("catch (Exception e)");
this.sessionContext.setRollbackOnly();
throw new AppErrorException(IExceptionConst.ERR_MSG_SYSMEMONO_00000, e.toString());
//throw new EJBException(IExceptionConst.ERR_MSG_SYSMEMONO_00000+", "+e.toString());
finally
log("this.sessionContext.getRollbackOnly()="+this.sessionContext.getRollbackOnly());
ResourceAssistant.cleanup(connection,statement);
return memono;

Can a method return more than one value?

I was studying for my biology exam and I got bored and I started thinking and then I wandered if a method can return more than one value...?
For example, if I want a method to return a row a column, I make a method that returns an int. But what if I want to return two ints? Or what If I want to return an integer and a string? Is it possible or do I have make two methods, each returning one thing?
What I always did until now is is I want for example to return a few integers, I would store them in a String and then when I return the string, I parse the numbers out using stringtokenizer... but it doesn't look like the best way... and it's pretty annoying...

I'm weak on terminology, hence I don't even know what
AFAIK means...As Far As I Know
This doesn't really make sense for me. It's more
efficient to make a whole class just for two
integers, than having two methods? Efficiency is not the point. The flow is.
If you have two methods, the caller must be aware of both of them. The other way it's up to the callee.
Just because the
two integers are related to each other? Doesn't
making a class require more memory usage than just
making two one-line methods?The memory usage is not wholly irrelevant, but there are ways to handle that (caching, inlining, etc.).
It's a bit hard to counter your point for me, but if you had done a lot of GUI painting stuff, you'd see all those Points, Dimensions, Rectangles, you name it, are quite invaluable.

Can java method return multiple values

hey , I need big favor can i return two arrays in a single function

Not directly no.
But there are ways around it.
You can create a "result object" which has attributes being the two arrays, and return that object (ie wrap the arrays in another object)
You could put the arrays into a collection (eg ArrayList/Vector) and then return that object. You can then retrieve the two arrays as the first two items in that list.
Either of those should work, even if they are hacks ;-)
Cheers,
evnafets

Problem calling a method in a servlet witch returns remote ejb

Hi, I have a problem combining servlets ands ejbs, I expose my problem :
What I have :
1 . I have a User table into a SGBD with two attributes login and pass.
2 . I have a UserBean linked to User table with a remote interface
3 . I have a stateless UserSessionBean with a remote interface
4 . I have a UserServlet linked to a jsp page which allows me to add users
5 . I use Jboss
What is working ?
1 - I have a method newUser implemented in my UserSessionBean :
public class UserSessionBean implements SessionBean {
private SessionContext sessionContext;
private UserRemoteHome userRemoteHome;
public void ejbCreate() throws CreateException {
// Initialize UserRemoteHome
// Method to add a new user
public UserRemote newUser(String login, String password) {
        UserRemote newUser = null;
        try {
            newUser = userRemoteHome.create(login, password);
        } catch (RemoteException ex) {
            System.err.println("Error: " + ex);
        } catch (CreateException ex) {
            System.err.println("Error: " + ex);
        return newUser;
}2 - When I test this method with a simple client it works perfectly :
public class TestEJB {
    public static void main(String[] args) {
        Context initialCtx;
        try {
            // Create JNDI context
            // Context initialization
            // Narrow UserSessionHome
            // Create UserSession
            UserSession session = sessionHome.create();
            // Test create
            UserRemote newUser = session.newUser("pierre", "hemici");
            if (newUser != null) {
                System.out.println(newUser.printMe());
        } catch (Exception e) {
            System.err.println("Error: " + e);
            e.printStackTrace();
Result : I got the newUser printed on STDOUT and I check in the User table (in the SGBD) if the new user has been created.
What I want ?
I want to call the newUser method from the UserServlet and use the RemoteUser returned by the method.
What I do ?
The jsp :
1 - I have a jsp page where a get information about the new user to create
2 - I put the login parameter and the password parameter into the request
3 - I call the UserServlet when the button "add" is pressed on the jsp page.
The Servlet :
1 - I have a method doInsert which call the newUser method :
public class UserServlet extends HttpServlet {
    private static final String CONTENT_TYPE = "text/html";
    // EJB Context
    InitialContext ejbCtx;
    // Session bean
    UserSession userSession;
    public void init() throws ServletException {
        try {
            // Open JNDI context (the same as TestClient context)
            // Get UserSession Home
            // Create UserSession
            userSession = userSessionHome.create();
        } catch (NamingException ex) {
            System.out.println("Error: " + ex);
        } catch (RemoteException ex) {
            System.out.println("Error: " + ex);
        } catch (CreateException ex) {
            System.out.println("Error: " + ex);
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws
            ServletException, IOException {
     * Does insertion of the new user in the database.
    public void doInsert(HttpServletRequest req, HttpServletResponse resp) throws
            ServletException, IOException {
        try {
            // Get parameters to create the newUser
            String login = req.getParameter("login");
            String password = req.getParameter("password");
           // Create the newUser
            System.out.println("Calling newUser before");
            UserRemote user = userSession.newUser(login, password);
            System.out.println("Calling newUser after");
        } catch (Exception e) {
    // Clean up resources
    public void destroy() {
Result :
When I run my jsp page and click on the "add" button, I got the message "Calling newUser before" printed in STDOUT and the error message :
ERROR [[userservlet]] Servlet.service() for servlet userservlet threw exception
javax.servlet.ServletException: loader constraints violated when linking javax/ejb/Handle class
     at noumea.user.UserServlet.service(UserServlet.java:112)
     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:153)
     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:534)
Constat :
I checked into my SGBD and the new user has been created.
The error appears only when the method return Remote ejbs, if I return simples objects (Strings, int..) it works.
What can I do to resolve this problem ?
Thank you.

"Why do you want to servlet to gain access to another EJB through the stateless session bean. Why cant the servlet call it directly ?"
Because I want to access to the informations included in the entity bean UserBean (which is remote).
You said that it is a bad design, but how can I access to my UserBean ejbs from the session bean if I don't do that ?
For example I want a List of all users to be seen in a jsp page :
1 - I call the method getUserList which returnsan ArrayList of UserRemote.
2 - I iterate over the ArrayList to get the users parameters to be seen.
As the other example (newUser), when I do
ArrayList users = (ArrayList) userSession.getUserList(); with the simple client it works, but in the servlet I got the same error.
But, if I call directly the findAll method (as you'are saying) in the servlet
ArrayList users = (ArrayList) userRemoteHome.findAll(); it works...
I think that if my servlet calls directly entity ejbs, I don't need UserSession bean anymore. Is that right ?
I precise that my design is this :
jsp -> servlet -> session bean -> entity bean -> sgbd
Is that a bad design ? Do I need the session bean anymore ?
Thank you.

Calling EJB method

Hi All,
I have never worked with EJBs so I am kind of stuck with one problem.
I have to make use of one existing EJB project through my external standard java class. The existing EJB project makes use of some other packages which are also EJB projects and I am not allowed to change any functionality of the EJB project but to use them as it is.
I am just initilizing the class object of the EJB project and calling its method. Within the EJB project there is a method which is calling another method of another EJB class.
The problem is that I dont see this other EJB class object getting initilized first and then calling its method as it happens in a normal scenario, hence when that method gets called i get a null pointer execption.
Let me give you some idea by posting some code snippet.
@WebService(targetNamespace = "http://www.ttt.de/ota")
@SOAPBinding(style = SOAPBinding.Style.DOCUMENT, use = SOAPBinding.Use.LITERAL, parameterStyle = SOAPBinding.ParameterStyle.BARE)
// standard EJB3 annotations
@Local(AMSAgencyWSPortType.class)
@Stateless
@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
// jboss propriatary annotations
@WebContext(transportGuarantee = "NONE", secureWSDLAccess = false)
public class AMSProfileServiceBean extends AbstractProfileBuilder implements AMSAgencyWSPortType
private static Log log = LogFactory.getLog(AMSMappingServiceBean.class);
@EJB(mappedName = "PotsdamProfileService/local")
private PotsdamProfileService profileService;
private Security              security;
@EJB
private OTAProfileBuilder     otaProfileBuilder;
@Override
public OTATTProfileReadRS otaTTReadRQ(Holder<Security> wsseHeader, OTATTReadRQ request)
     security = wsseHeader.value;
     BigDecimal requestVersion = request.getVersion();
     OTATTProfileReadRS otaProfileReadRS = new OTATTProfileReadRS();
     otaProfileReadRS.setVersion(requestVersion);
     PotsdamInstanceKey profileIntanceKey;
    try
      profileIntanceKey = getKeyHandler(requestVersion).buildUserKey(wsseHeader);
      PotsdamInstance userInstance = loadProfileFromPotsdam(profileIntanceKey);
private PotsdamInstance loadProfileFromPotsdam(PotsdamInstanceKey userCredentials) throws PotsdamException
       PotsdamInstance potsdamInstance = null;
       try{
    Holder<com.ttt.potsdam.common.messages.Security> wsseHeader = buildWsseHeader(security);
    ProfileResponse potsdamInstanceRS = profileService.loadProfile(wsseHeader, userCredentials);
...I get an error message before the sequence reaches loadProfile(..), which in my sense is due to the fact that 'profileService' never was initilized in the EJB project.
profileService is object of another EJB project, which looks somethign like this:
@Stateless
@LocalBinding(jndiBinding = "PotsdamProfileService/local")
// jboss 4.2
@org.jboss.annotation.ejb.LocalBinding(jndiBinding = "PotsdamProfileService/local")
public class PotsdamProfileServiceBean implements PotsdamProfileService {
     private static Log log = LogFactory.getLog(PotsdamProfileServiceBean.class);
     @EJB
     private CacheProfileService cacheProfileService;
     @EJB(mappedName = "/PersistenceUnitsManagerBean/local")
     private PersistenceUnitsManager persistenceUnitsManager;
     @EJB
     private PotsdamService potsdamService;
     public ProfileResponse loadProfile(Holder<Security> wsseHeader,
               PotsdamInstanceKey cacheInstanceKey) {
           log.debug("inside loadProfile");
...Now I am calling the main EJB like this:
PotsdamotaTTReadRQ();
public OTATTProfileReadRS PotsdamotaTTReadRQ()
       AMSProfileServiceBean a = new AMSProfileServiceBean();
       Holder<Security> wsseHeader = new Holder<Security>();
       OTATTProfileReadRS response = a.otaTTReadRQ(wsseHeader, request);
       return response;
}So my confusion is how can I make use of profileService.loadProfile(wsseHeader, userCredentials); ??
I tried to initilize: PotsdamProfileServiceBean profileService = new PotsdamProfileServiceBean();but I get jndi binding and lots of other exception.
Please help.
Edited by: 925515 on 04.07.2012 06:40

Thanks for your pointer. Could you please help me out with a small code snippet example?
I want to make use of this existing bean (AMSProfileServiceBean ):
@WebService(targetNamespace = "http://www.ttt.de/ota")
@SOAPBinding(style = SOAPBinding.Style.DOCUMENT, use = SOAPBinding.Use.LITERAL, parameterStyle = SOAPBinding.ParameterStyle.BARE)
// standard EJB3 annotations
@Local(AMSAgencyWSPortType.class)
@Stateless
@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
// jboss propriatary annotations
@WebContext(transportGuarantee = "NONE", secureWSDLAccess = false)
public class AMSProfileServiceBean extends AbstractProfileBuilder implements AMSAgencyWSPortType
private static Log log = LogFactory.getLog(AMSMappingServiceBean.class);
@EJB(mappedName = "PotsdamProfileService/local")
private PotsdamProfileService profileService;
private Security              security;
@EJB
private OTAProfileBuilder     otaProfileBuilder;
@EJB
private OTAProfileUpdater     otaProfileUpdater;
@Override
public OTATTProfileReadRS otaTTReadRQ(Holder<Security> wsseHeader, OTATTReadRQ request)
...in my soap-connector :
@WebServiceProvider(wsdlLocation = "WEB-INF/wsdl/PotsdamAMSAgencyWS.wsdl", targetNamespace = "http://www.ttt.de/ota", serviceName = "PotsdamAMSAgencyWS", portName = "PotsdamAMSAgencyWSPortType")
@ServiceMode(value = Service.Mode.MESSAGE)
public class PotsdamAgencyWSProvider extends WSProvider implements Provider<SOAPMessage>
@Resource
WebServiceContext     wsCtx;
...A small example would be really appreciated.
Thanks.

EJB as a Client to another EJB in 6.0

I have an EJB that calls another EJB. I understand that to call the first EJB from a java Client, I need to have the home and remote interface in the path of the Client. However, when the EJB locates the 2nd EJB through JNDI, I'm getting an exception that the 2nd EJB does not have access to the first EJBs interfaces. When I physically put the first EJBs home and remote interfaces in the /config/examples/serverclasses directory that is explicitly included in the CLASSPATH, the call to the second bean is successful. Why don't the EJBs have access to each others interaces?

Because they either need to be in the same .jar or in the same .ear.
Gene
"Clay Barrow" <[email protected]> wrote in message news:3a7989fa$[email protected]..
I have an EJB that calls another EJB. I understand that to call the first EJB from a java Client,I need to have the home and remote interface in the path of the Client. However, when the EJB
locates the 2nd EJB through JNDI, I'm getting an exception that the 2nd EJB does not have access to
the first EJBs interfaces. When I physically put the first EJBs home and remote interfaces in the
/config/examples/serverclasses directory that is explicitly included in the CLASSPATH, the call to
the second bean is successful. Why don't the EJBs have access to each others interaces?

ClassCastException when I access an EJB from a remote EJB in WL 8.1

I am using WebLogic 8.1 and am trying to lookup the home interface for an EJB (_ejbRemote_)
from another EJB (_ejbCurrent_). They are deployed in seperate EARs. When I bundle
the home and remote interfaces for ejbRemote in the EAR file that ejbCurrent
is deployed in, everything works fine. But I need to be able to configure ejbRemote
at run time and my customers don't want to have to bundle their classes in my
EAR. So I invoke a custom classloader (of type java.net.URLClassLoader) that will
load the home and remote interface classes for ejbRemote from a configurable
location at runtime. This finds the classes no problem, and the InitialContext.lookup()
returns a stub, but I get a 'java.lang.ClassCastException: Cannot narrow remote
object' error when I call PortableRemoteObject.narrow(home, homeClass);
The code looks like:
// Assume EJBHomeStr = "com.foo.TestHome" in this case
// Load the home interface class. This works.
Class homeClass = urlClassLoader.loadClass(EJBHomeStr);
// Lookup the home interface. This works.
Object lookedUpHomeObject = initialContext.lookup(JNDIName);
// This fails.
Object homeObject = PortableRemoteObject.narrow(lookedUpHomeObject, homeClass);
And the weblogic error looks like
... ; nested exception is:
java.lang.ClassCastException: Cannot narrow remote object to com.foo.TestHome
at weblogic.iiop.PortableRemoteObjectDelegateImpl.narrow(PortableRemoteO
bjectDelegateImpl.java:219)
at javax.rmi.PortableRemoteObject.narrow(PortableRemoteObject.java:134)
at ...[the rest is just my application code stack...]
When I log the ClassLoaders for the affected objects, using getClass().getClassLoader(),
I get:
<snippet from log follows>
getClass().getClassLoader(): weblogic.utils.classloaders.GenericClassLoader@667da1
finder:
weblogic.utils.classloaders.MultiClassFinder@db9199 annotation: myEJBApp@
homeClass.getName(): com.foo.TestHome classloader = java.net.URLClassLoader@4f1707
lookedUpHomeObject.getClass().getName(): com.foo.Test_EJB_kx82zy_HomeImpl_810_WLStub
classloader = weblogic.utils.classloaders.GenericClassLoader@667da1
finder: weblogic.utils.classloaders.MultiClassFinder@db9199 annotation: myEJBApp@
<end snippet from log>
So it appears that since the looked up Stub was loaded by the WebLogic classloader
and the actual Home class was loaded by my URLClassLoader, the narrow() can't
reconcile the two. I have tried both rmic and the Weblogic appc command to pre-generate
the stubs, which I put in the same JAR as my home and remote interface classes
and load with my custom classloader. But the standard stub (generated by either
rmic or appc) is named TestHomeStub.class and Weblogic is ignoring those and
making a class with the name Test_EJB_kx82zy_HomeImpl_810_WLStub, as shown above.
I have also tried to put the remote interface classes and stubs in the System
classpath using the -classpath option when I start WebLogic, but same result.
The question is, Is there a way in WebLogic to communicate with a remote EJB in
a seperate EAR without bundling anything about that remote EAR in my EAR? Or is
there something I've missed? I need to keep my application J2EE compliant, meaning
I can't hardcode any AppServer-specific code in my application.
Thanks.

Hi Jon,
Glad to hear that.
Regards,
Slava Imeshev
"Jon Sutula" <[email protected]> wrote in message news:[email protected]...
>
I fixed the problem. It turns out I didn't need to use a custom classloader at
all, I just use Reflection directly on the classes ruturned from my JNDI lookup.
So when I lookup the home class, I don't need to narrow or cast it, I just use
Reflection to invoke the "create" method. Then I use the object that I get from
create and directly invoke whatever method on it I need, again using Reflection.
And that works.
"Slava Imeshev" <[email protected]> wrote:
Hi Jon,
The problem is, this class is not available for the classloader
running your "main code".
You can try to hack the into the thread context class loader:
Thread thread = Thread.currentThread();
ContextClassLoader originalClassLoader = thread.getContextClassLoader();
try {
YourURLClassloader yourClassLoader = new
YourURLClassloader(originalClassLoader);
thread.setContextClassLoader(yourClassLoader );
// your code goes here
} finally {
// Don't forget to restore it !!!
thread.setContextClassLoader(originalClassLoader);
Be very cautious. If you fail to restore the original context class loader,
you will likely have to restart the server.
Hope this helps.
Regards,
Slava Imeshev
"Jon Sutula" <[email protected]> wrote in message news:[email protected]...
I am using WebLogic 8.1 and am trying to lookup the home interfacefor an EJB (_ejbRemote_)
from another EJB (_ejbCurrent_). They are deployed in seperate EARs.When I bundle
the home and remote interfaces for ejbRemote in the EAR file that
ejbCurrent
is deployed in, everything works fine. But I need to be able to configure
ejbRemote
at run time and my customers don't want to have to bundle their classesin my
EAR. So I invoke a custom classloader (of type java.net.URLClassLoader)that will
load the home and remote interface classes for ejbRemote from a configurable
location at runtime. This finds the classes no problem, and the InitialContext.lookup()
returns a stub, but I get a 'java.lang.ClassCastException: Cannot narrowremote
object' error when I call PortableRemoteObject.narrow(home, homeClass);
The code looks like:
// Assume EJBHomeStr = "com.foo.TestHome" in this case
// Load the home interface class. This works.
Class homeClass = urlClassLoader.loadClass(EJBHomeStr);
// Lookup the home interface. This works.
Object lookedUpHomeObject = initialContext.lookup(JNDIName);
// This fails.
Object homeObject = PortableRemoteObject.narrow(lookedUpHomeObject,homeClass);
And the weblogic error looks like
... ; nested exception is:
java.lang.ClassCastException: Cannot narrow remote object tocom.foo.TestHome
at weblogic.iiop.PortableRemoteObjectDelegateImpl.narrow(PortableRemoteO
bjectDelegateImpl.java:219)
at javax.rmi.PortableRemoteObject.narrow(PortableRemoteObject.java:134)
at ...[the rest is just my application code stack...]
When I log the ClassLoaders for the affected objects, using getClass().getClassLoader(),
I get:
<snippet from log follows>
getClass().getClassLoader(): weblogic.utils.classloaders.GenericClassLoader@667da1
finder:
weblogic.utils.classloaders.MultiClassFinder@db9199 annotation: myEJBApp@
homeClass.getName(): com.foo.TestHome classloader = java.net.URLClassLoader@4f1707
lookedUpHomeObject.getClass().getName(): com.foo.Test_EJB_kx82zy_HomeImpl_810_WLStub
classloader = weblogic.utils.classloaders.GenericClassLoader@667da1
finder: weblogic.utils.classloaders.MultiClassFinder@db9199 annotation:myEJBApp@
<end snippet from log>
So it appears that since the looked up Stub was loaded by the WebLogicclassloader
and the actual Home class was loaded by my URLClassLoader, the narrow()can't
reconcile the two. I have tried both rmic and the Weblogic appc commandto pre-generate
the stubs, which I put in the same JAR as my home and remote interfaceclasses
and load with my custom classloader. But the standard stub (generatedby either
rmic or appc) is named TestHomeStub.class and Weblogic is ignoringthose and
making a class with the name Test_EJB_kx82zy_HomeImpl_810_WLStub, asshown above.
I have also tried to put the remote interface classes and stubs inthe System
classpath using the -classpath option when I start WebLogic, but sameresult.
The question is, Is there a way in WebLogic to communicate with a remoteEJB in
a seperate EAR without bundling anything about that remote EAR in myEAR? Or is
there something I've missed? I need to keep my application J2EE compliant,meaning
I can't hardcode any AppServer-specific code in my application.
Thanks.

Timer created by EJB never triggered unless EJB called locally

Hi,
I'm using weblogic 5.1 service pack 6. JDK 1.2.2.
A call to a method of a stateless session EJB deployed on this server
sets up a Time Service trigger to perform an action only a few seconds
later.
Currently when I call this EJB method from a servlet on the same server
everything works as expected - the calls returns without error and a few
second later the trigger is set off and that action too completes
successfully.
However when I call the same EJB from a separate test program
(inside Forte), the EJB method appears to function perfectly - the
trigger appears to be set up correctly, the setServices and sheduleInit
and schedule methods of the Schedule object are all called, and the
setServices and triggerInit methods of the Trigger are both called. The
EJB method returns correctly.
However, in this case the Trigger is never activated.
Can anyone explain?
Thanks,
Richard.

Thank you very much, that did the trick.
Regards,
Rich.
Don Ferguson <[email protected]> wrote in message news:<[email protected]>...
This is just a guess, but try setting the timer to be a "Daemon", as in :
scheduledTrigger.setDaemon(true)
Probably what is happening is that the client has disconnected, and
resources associated with that client (including the timer) have been
reclaimed.
-Don
Richard Carr wrote:
Hi,
I'm using weblogic 5.1 service pack 6. JDK 1.2.2.
A call to a method of a stateless session EJB deployed on this server
sets up a Time Service trigger to perform an action only a few seconds
later.
Currently when I call this EJB method from a servlet on the same server
everything works as expected - the calls returns without error and a few
second later the trigger is set off and that action too completes
successfully.
However when I call the same EJB from a separate test program
(inside Forte), the EJB method appears to function perfectly - the
trigger appears to be set up correctly, the setServices and sheduleInit
and schedule methods of the Schedule object are all called, and the
setServices and triggerInit methods of the Trigger are both called. The
EJB method returns correctly.
However, in this case the Trigger is never activated.
Can anyone explain?
Thanks,
Richard.

Can EJB method return another EJB?

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