can not found interface class

[Simon Simbolon]

Hi, all

I'm still new to RMI, so please be gentle

I'm trying to create an RMI server using netbeans, but I'm having some difficulties. Here is my code:

the interfaceJar:

package interfaces;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface Calculator extends Remote {
    public long add(long a, long b) throws RemoteException;

    public long sub(long a, long b) throws RemoteException;

    public long mul(long a, long b) throws RemoteException;

    public long div(long a, long b) throws RemoteException;
    
    public long sum(long a, long b) throws RemoteException;
}

The implementationJar:
1st class:

package server;
import interfaces.Calculator;
import java.rmi.*;
import java.rmi.server.*;

public class CalculatorImpl extends UnicastRemoteObject implements Calculator {
    CalculatorImpl() throws RemoteException{
        super();
    }
    public long sum(long a,long b) throws RemoteException {
        return a + b;
    }

    public long add(long a, long b) throws RemoteException {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    public long sub(long a, long b) throws RemoteException {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    public long mul(long a, long b) throws RemoteException {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    public long div(long a, long b) throws RemoteException {
        throw new UnsupportedOperationException("Not supported yet.");
    }

2nd class:

package server;

import java.rmi.Naming;
import java.rmi.RMISecurityManager;
import java.rmi.RemoteException;
public class CalculatorServer {

   public CalculatorServer() {
       try {
           if (System.getSecurityManager() == null) {
               System.setSecurityManager(new RMISecurityManager());
               System.out.println("new security manager created");
           }

           System.out.println("begin creating server..");
           CalculatorImpl Server = new CalculatorImpl();
           System.out.println("server created");

           System.out.println("begin binding..");
           Naming.rebind("CalculatorTesting", Server);
           System.out.println("binding succeeded");

           System.out.println("waiting...");
       
       } catch (java.net.MalformedURLException me){
           System.out.println("Malformed URL: " + me.toString());
       } catch (RemoteException e){
           System.out.println("Remote Exception: ");
           e.printStackTrace();
       } catch (Exception e) {
           System.out.println("Trouble: " + e);
           e.printStackTrace();
     }
   }

   public static void main(String args[]){
       new CalculatorServer();
   }

I build both jar and put them with this hierarchy in the server:
/opt/temp/implementationJar.jar
/opt/temp/lib/interfaceJar.jar

but when I run the command: java -jar implementationJar.jar, i got following error:

java.rmi.UnexpectedException: undeclared checked exception; nested exception is:
java.lang.ClassNotFoundException: Could not find class (interfaces.Calculator) at codebase ()
at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source)
at java.rmi.Naming.rebind(Naming.java:160)
at server.CalculatorServer.<init>(CalculatorServer.java:31)
at server.CalculatorServer.main(CalculatorServer.java:48)
Caused by: java.lang.ClassNotFoundException: Could not find class (interfaces.Calculator) at codebase ()
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:255)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:233)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:359)

What did I do wrong?

[Karthik Shiraly]

Hi,
Include Interfaces.jar in classpath with -cp option.
Setting up RMI needs attention - lots of things that can go wrong. It's a good idea to read RMI tutorial
and RMI FAQ thoroughly first, if you haven't done so already.

[Simon Simbolon]

I've tried adding the -cp, so the command like are like this:
java -cp /opt/temp/lib/interfaceJar.jar -jar implementationJar.jar
but the error is still occurs.

I've also tried to add the codebase property:
java -Djava.security.policy=/opt/event-logger-client/wideopen.policy -Djava.rmi.server.codebase=file:///opt/temp/lib/isengInterfaces.jar -jar isengServer.jar
but instead I found error:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassCastException: java.io.ObjectStreamClass cannot be cast to java.lang.String
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:255)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:233)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:359)
at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source)
at java.rmi.Naming.rebind(Naming.java:160)
at server.CalculatorServer.<init>(CalculatorServer.java:31)
at server.CalculatorServer.main(CalculatorServer.java:48)
Caused by: java.lang.ClassCastException: java.io.ObjectStreamClass cannot be cast to java.lang.String

please help?

[Karthik Shiraly]

Hi,

One of these should be done.
1) rmiregistry has the interface jar in its classpath, OR
2) rmiregistry is running with -Djava.rmi.server.codebase set, OR
3) rmiregistry runs without either settings, but then server should run with -Djava.rmi.server.codebase set.
All these are so that the Naming binding can find the interface and tack it onto the dynamically created stub.

Mandatorily, the server should also have -cp interface.jar. This is nothing to with the binding, but because your server has a runtime dependency on the interface.

Also go through this article on dynamic code downloading

[Arpita Shah]

For a really good review of reporting systems available on SharePoint, take a look at http://www.sharepointreporting.info/