Dynamic EJB Client

Question

Hi there,
I've a runtime problem. I don't know until runtime which ejb my client program wishes to lookup. Is there anyway of creating/retrieving the instance of a bean at runtime and ivoking business methods on the remote interface dynamically.
All information I have got is this.
String MyEjbBindName = args[0];
String MyEjbHomeName = args[1];
String MyEjbRemoteName = args[2];
String MyEJbMethodName = args[3];
Any ideas would be greatly appreciated. Thanks,
Raj.

Answer 1

Hy,
It is posible
This is the code:
========================
package com.somepackage;
import java.util.Properties;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.ejb.EJBHome;
import javax.ejb.EJBException;
import javax.rmi.PortableRemoteObject;
public class EjbProxy
private Properties _prop = null;
public EjbProxy()
public EjbProxy (String initContextFactory, String providerUrl)
setContextProperties (initContextFactory, providerUrl, null, null);
public EjbProxy (Properties prop)
setContextProperties (prop);
public void setContextProperties (Properties prop)
_prop = prop;
public void setContextProperties (String initContextFactory, String providerUrl,
String user, String password)
_prop = new Properties ();
prop.put (Context.INITIALCONTEXT_FACTORY, initContextFactory);
prop.put (Context.PROVIDERURL, providerUrl);
if (user != null)
     prop.put(Context.SECURITYPRINCIPAL, user);
     if (password == null)
          password = "";
     prop.put(Context.SECURITYCREDENTIALS, password);
public void setContextUserParam (String user, String password)
if (_prop == null)
_prop = new Properties ();
prop.put(Context.SECURITYPRINCIPAL, user);
prop.put(Context.SECURITYCREDENTIALS, password);
public EJBHome getHome (String beanJndiLookupName) throws EJBException
try
InitialContext ctx = null;
     if (_prop != null)
          ctx = new InitialContext (_prop);
     else
          ctx = new InitialContext ();
Object home = ctx.lookup(beanJndiLookupName);
EJBHome obHome = (EJBHome)PortableRemoteObject.narrow (home, EJBHome.class);
return obHome;
catch (NamingException ne)
throw new EJBException (ne);
catch (Exception e)
               e.printStackTrace();
throw new EJBException (e);
public Object getObj (String beanJndiLookupName) throws EJBException
try
EJBHome obHome = getHome (beanJndiLookupName);
//get the method of create
Method m = obHome.getClass().getDeclaredMethod("create", new Class[0]);
//invoke the create method
Object obj = m.invoke (obHome, new Object[0]);
return obj;
catch (NoSuchMethodException ne)
throw new EJBException (ne);
catch (InvocationTargetException ie)
throw new EJBException (ie);
catch (IllegalAccessException iae)
throw new EJBException (iae);
=====================================
You can also get the code an further explanations from
http://www.javaworld.com/javaworld/javatips/jw-javatip118.html
Here you have something similar, but not that good:
http://www.devx.com/premier/mgznarch/javapro/2001/02feb01/ru0102/ru0102.asp
Now, the idea is that you can lookup a bean by only using it's jndi lookup name!
This works fine..
But, you must have your home and remote interface in your application classpath,
otherwise you'll be unable to compile your code!
And even if you would compile it, javax.InitialContext.lookup wouldn't create your
object(it also checks in your classpath).
You don't need this, do you?
have a nice day,
rudi vaum
[email protected]