Problem running a simple Hello World RMI Program

Question

I wrote a simple RMI application, consisting of a Server Interface, Server Implementation and a Client.
Since the codes are really small, am pasting them here so that you could identify the problem if any, in the code.
1. Server Interface......
import java.rmi.* ;
public interface HelloInterface extends java.rmi.Remote
     public void sayHello(String arg) throws RemoteException ;
2. Server Implementation......
import java.rmi.* ;
import java.rmi.server.* ;
public class HelloImpl extends UnicastRemoteObject implements HelloInterface
     public HelloImpl() throws RemoteException
          super() ;
     public void sayHello(String arg) throws RemoteException{
          try{
               System.out.println("RMI Program : Hello "+arg) ;
          catch(Exception e){
               e.printStackTrace() ;
               //throw new java.rmi.UnexpectedException("undeclared checked exception", e);
     public static void main(String[] args) throws RemoteException
          try{
               if( System.getSecurityManager() == null )
                    System.setSecurityManager( new RMISecurityManager() ) ;
               HelloImpl impl = new HelloImpl() ;
               Naming.bind("HelloService",impl) ;
               System.out.println( "Service bound..." ) ;
          catch(Exception e){
               e.printStackTrace() ;
               //throw new java.rmi.UnexpectedException("undeclared checked exception", e);
3. Client Code.
import java.rmi.* ;
import java.rmi.Naming.* ;
class RMIClient
     public static void main(String[] args)
          try{
               if(System.getSecurityManager()==null)
                    System.setSecurityManager( new RMISecurityManager() ) ;
               HelloInterface helloInt = (HelloInterface) Naming.lookup("rmi://sand.cise.ufl.edu/HelloService") ;
               helloInt.sayHello("Ranjit") ;
          catch(Exception e){
               e.printStackTrace() ;
I have double checked the classpaths and they all look fine..
I have even unset the classpath from the shell which runs the rmiregistry..am still getting these errors..
1. If i use the default java to run the application..this is the error that it spits..
sand:24% java -Djava.security.policy=java.policy HelloImpl
java.rmi.UnexpectedException: undeclared checked exception; nested exception is:
java.lang.ClassNotFoundException: HelloImpl_Stub
at sun.rmi.registry.RegistryImpl_Stub.bind(Unknown Source)
at java.rmi.Naming.bind(Naming.java:110)
at HelloImpl.main(HelloImpl.java:28)
Caused by: java.lang.ClassNotFoundException: HelloImpl_Stub
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:247)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:223)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:350)
... 3 more
2. Using java from some other location..the error looks different...but in both cases it just gives errors :((
sand:25% /usr/java1.2/bin/java -Djava.security.policy=java.policy HelloImpl
java.rmi.UnexpectedException: undeclared checked exception; nested exception is:
java.lang.ClassNotFoundException: HelloImpl_Stub
java.lang.ClassNotFoundException: HelloImpl_Stub
at java.lang.Throwable.fillInStackTrace(Native Method)
at java.lang.Throwable.fillInStackTrace(Compiled Code)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Compiled Code)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:223)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:342)
at sun.rmi.registry.RegistryImpl_Stub.bind(Unknown Source)
at java.rmi.Naming.bind(Naming.java:116)
at HelloImpl.main(HelloImpl.java:28)
I am embarking on a huge assignment but if am having problems getting started..
Your help will be highly appreciated..
thanx and regards
Ranjit Iyer

Answer 1

First of all you should be posting this Q in the RMI forum :)
You are getting that error because your stub is not in your clients classpath (or u can say the compiler is not able to find it).
Make sure that the file HelloImpl_Stub is in the client classpath/package.
Regards
Meka Toka