1 Reply Latest reply on Mar 4, 2008 8:15 AM by jaikiran

    Queer error: java.lang.LinkageError: loader constraints viol

    subhash.bhushan
    subhash.bhushan Mar 4, 2008 4:54 AM

      Hi,

      I faced a queer error with JBoss 4.2.2 GA, so thought of reporting it even though I managed to circumvent the problem.

      I have a stateless EJB LoginBean, with remote interface Login:

      Remote Interface:

      package com.justbooks.security;

import javax.ejb.Remote;

import com.justbooks.entities.Profile;

@Remote
public interface Login {
 public boolean signOn(Profile profile);
 public boolean signOn(String loginName, String loginPassword);
}

      Bean Class: 
      package com.justbooks.security;

import javax.ejb.Stateless;

import com.justbooks.entities.Profile;
import com.justbooks.security.Login;
import javax.persistence.*;
import com.justbooks.utility.*;

public @Stateless class LoginBean implements Login


      I have a DAO Stateless EJB called ProfileDAOBean, with remote interface ProfileDAO:

      Remote Interface: 
      package com.justbooks.dao;

import javax.ejb.Remote;

import com.justbooks.entities.Profile;

@Remote
public interface ProfileDAO {
 public Profile findProfile(String loginName);
 public boolean authenticate(String loginName, String loginPassword);
 public boolean changePassword(String loginName, String oldPassword,
 String newPassword);

}

      Bean Class: 
      package com.justbooks.dao;

import javax.naming.Context;
import javax.naming.NamingException;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
import javax.ejb.Stateless;

import com.justbooks.utility.EJBFinder;
import com.justbooks.entities.Profile;
import com.justbooks.security.ChangePassword;
import com.justbooks.security.Login;

public @Stateless class ProfileDAOBean implements ProfileDAO


      If I include the lookup code for LoginBean inside ProfileDAOBean, then the application works just fine. But if I use a helper class to find EJBs, my application throws up an error saying
      15:01:57,890 ERROR [[default]] Servlet.service() for servlet default threw exception
      java.lang.LinkageError: loader constraints violated when linking com/justbooks/security/Login class


      EJBHelper: 
      package com.justbooks.utility;

import javax.naming.Context;
import javax.naming.NamingException;

import com.justbooks.security.ChangePassword;
import com.justbooks.security.Login;

public final class EJBHelper {
 private static Context getInitialContext()
 throws javax.naming.NamingException
 {
 return new javax.naming.InitialContext();
 }

 public static Login getLoginEJB() {
 try {
 Context jndiContext = getInitialContext();
 //TODO put these lookup strings in properties file
 Object ref = jndiContext.lookup("JustAutomate/LoginBean/remote");
 Login login = (Login)ref;
 return login;
 }catch (NamingException ne) {
 ne.printStackTrace();
 return null;
 }
 }

 public static ChangePassword getChangePasswordEJB() {
 try {
 Context jndiContext = getInitialContext();
 //TODO put these lookup strings in properties file
 Object ref = jndiContext.lookup("JustAutomate/ChangePasswordBean/remote");
 ChangePassword changePassword = (ChangePassword)ref;
 return changePassword;
 }catch (NamingException ne) {
 ne.printStackTrace();
 return null;
 }
 }
}


      If I change the name of the class to EJBFinder, then everything starts working fine again. Not sure what the problem is.

      As of now, I have circumvented the problem by renaming the class from EJBHelper to EJBFinder.

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