Running RMI Server, got errors with marshalling arguments and class not found

Question

I'm following a tut that show how to create a RMI project.

But when I run the Server site, it has errors. When I run: rmic CalculatorImpl, it just creates stub, I dont see ske.

This is the log when I run rmic CalculatorImpl:

Warning: generation and use of skeletons and static stubs for JRMP is deprecated. Skeletons are unnecessary, and static stubs have been superseded by dynamically generated stubs. Users are encouraged to migrate away from using rmic to generate skeletons and static stubs. See the documentation for java.rmi.server.UnicastRemoteObject.

And when I run CalculatorServer:

java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: CalculatorImpl_Stub

This is my code:

File CalculatorServer:

public class CalculatorServer {
public CalculatorServer() {
    try {
        Calculator c = new CalculatorImpl();
        Naming.bind("rmi://localhost:1099/CalculatorService", c);
    } catch (Exception e) {
        System.out.println("Trouble: " + e);
    }
}

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

File Calculator:

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

And file CalculatorImpl:

public class CalculatorImpl extends
    java.rmi.server.UnicastRemoteObject implements Calculator {
public CalculatorImpl()
        throws java.rmi.RemoteException {
    super();
}

public long add(long a, long b)
        throws java.rmi.RemoteException {
    return a + b;
}
}

And the CalculatorClient in another project:

public class CalculatorClient {

public static void main(String[] args) {
    try {
        Calculator c = (Calculator)
                Naming.lookup(
                        "rmi://localhost/CalculatorService");
        System.out.println( c.add(4, 5) );

    }
    catch (MalformedURLException murle) {
        System.out.println();

        System.out.println(
                "MalformedURLException");
        System.out.println(murle);
    }
    catch (RemoteException re) {
        System.out.println();
        System.out.println(
                "RemoteException");
        System.out.println(re);
    }
    catch (NotBoundException nbe) {
        System.out.println();
        System.out.println(
                "NotBoundException");
        System.out.println(nbe);
    }
    catch (
            java.lang.ArithmeticException
                    ae) {
        System.out.println();
        System.out.println(
                "java.lang.ArithmeticException");
        System.out.println(ae);
    }
}
}

So please help me.Tks all!

That must be an old tutorial. You don't need to run `rmic` anymore. — erickson, Jul 21 '16 at 19:07
@erickson He does with that code. He would need `super(0);` to avoid `rmic`. — user207421, Jul 21 '16 at 19:08

Alexander Petrov · Accepted Answer · 2016-07-21T19:55:36.400

0

Summarizing the comment chain.

What is essential is that the registry should be aware of the Server stub. In order for this to happen, there are two options. Option one is the Registry and the Server to share the same VM. This can be achieved through

adding LocateRegistry.createRegistry() In the beginning of the server main class.

Option two is

two configure the server to use automatic download of the stub files this can be achieved through java.rmi.server.codebase

example command

java -cp c:\home\ann\src;c:\home\ann\public_html\classes\compute.jar
     -Djava.rmi.server.codebase=file:/c:/home/ann/public_html/classes/compute.jar
     -Djava.rmi.server.hostname=mycomputer.example.com
     -Djava.security.policy=server.policy
        engine.ComputeEngine

this is taken from https://docs.oracle.com/javase/tutorial/rmi/running.html

edited Jul 21 '16 at 19:55

answered Jul 21 '16 at 18:12

Alexander Petrov

9,204
31
70

I created Client site in another projects. So, should I move it to current project ? – MiH Jul 21 '16 at 18:15
This should not be necessary. Read point 6.1 from the link I sent you. It contains the exact same error you have posted. – Alexander Petrov Jul 21 '16 at 18:16
Note that the codebase can point to a directory. It is not necessary to be a URL – Alexander Petrov Jul 21 '16 at 18:17
I added -Djava.rmi.server.codebase to run CalculatorServer, but it still error – MiH Jul 21 '16 at 18:26
Try creating the registry from your code LocateRegistry.createRegistry() This way both the Server and the Registry will be running in the same VM – Alexander Petrov Jul 21 '16 at 18:34
Sorry, where should I add LocateRegistry.createRegistry() to my code ? I'm newbie :( so I'm sorry – MiH Jul 21 '16 at 18:35
Ok I think I am starting to get what is the problem. The Stub needs to be available in the class path of your Registry. So you have two options. Option 1 is to put your server jar file in the class path of the Registry. Option 2 is to start the Registry in the same JVM as your server through LocateRegistry.createRegistry() – Alexander Petrov Jul 21 '16 at 18:35
Right above Calculator c = new CalculatorImpl(); in the server – Alexander Petrov Jul 21 '16 at 18:36
I run rmiregistry in the cmd.So is it needed – MiH Jul 21 '16 at 18:37
If you put the line I told you. You no longer need to run it from the command line – Alexander Petrov Jul 21 '16 at 18:37
As I said two options. Option 1 is start Registry from your server. Option 2 start registry from your command line, but then you put your server jar file in the class path when you are starting the registry – Alexander Petrov Jul 21 '16 at 18:38
Lets make it work and I will describe everything beautiful in the answer – Alexander Petrov Jul 21 '16 at 18:39
Ya. I put to that line, but it shows cannot resolve method createRegistry; – MiH Jul 21 '16 at 18:39
Wait a sec, the version of RMI may have changed . One moment to test it. – Alexander Petrov Jul 21 '16 at 18:40
You are wrong there is such method with signature LocateRegistry.createRegistry(port) you just need to assign the port. If my memory is correct the default port should be 1099 – Alexander Petrov Jul 21 '16 at 18:42
Ok.Thank you.I'll wait – MiH Jul 21 '16 at 18:42
java.rmi.server.ExportException: Port already in use: 1099; nested exception is: java.net.BindException: Address already in use: JVM_Bind – MiH Jul 21 '16 at 18:42
Or alternatively another application is occupying it. Either find out what is this application and kill it , or just change the port. – Alexander Petrov Jul 21 '16 at 18:45
java.rmi.ConnectException: Connection refused to host: localhost; nested exception is: java.net.ConnectException: Connection refused: connect – MiH Jul 21 '16 at 18:46
I'm so sorry if I take your time – MiH Jul 21 '16 at 18:47
What are you doing now ? – Alexander Petrov Jul 21 '16 at 18:47
That is next error and when I can start server, I want to start Client to test it – MiH Jul 21 '16 at 18:47
I stop the command and I put that method to my code and I use port 1099 – MiH Jul 21 '16 at 18:51
I dont know but when I run it still error: java.rmi.ConnectException: Connection refused to host: localhost; nested exception is: java.net.ConnectException: Connection refused: connect – MiH Jul 21 '16 at 18:54
Is this when you start server or client ? – Alexander Petrov Jul 21 '16 at 18:55
Hmm... this is very strange. I just started it the server on my PC – Alexander Petrov Jul 21 '16 at 19:00
public CalculatorServer() { try { LocateRegistry.createRegistry(1099); Calculator c = new CalculatorImpl(); Naming.bind("rmi://localhost:1099/CalculatorService", c); } catch (Exception e) { System.out.println("Trouble: " + e); } } – Alexander Petrov Jul 21 '16 at 19:00
Can u teamview ? I send u – MiH Jul 21 '16 at 19:00
can you send me the client code first to test the server – Alexander Petrov Jul 21 '16 at 19:01
I fixed it. I'm sorry – MiH Jul 21 '16 at 19:04
so how to I fix it :( – MiH Jul 21 '16 at 19:06
Now I will write one nice answer to explain two two scenarios. Which registry through command line and registry through the application. – Alexander Petrov Jul 21 '16 at 19:07
So what did you fix it :( – MiH Jul 21 '16 at 19:10
Using the codebase feature is not essential. There are other solutions. – user207421 Jul 21 '16 at 19:12
So are you write a nice answer :( – MiH Jul 21 '16 at 19:15
Yes it is not. If I understand correctly and this is what I was trying to push to the other end. What is important is the Stub to be available in the class path of the registry. Which can be achieved either if the Server and the registry run in single VM or if the server is passed in the class path of the registry . Right ? @EJP ? – Alexander Petrov Jul 21 '16 at 19:15
What I have to do now :( – MiH Jul 21 '16 at 19:18
Don't accept my answer if you have not made it run. You never know if I am wrong. – Alexander Petrov Jul 21 '16 at 19:25
You said something about team viewer lets have a look – Alexander Petrov Jul 21 '16 at 19:25
So answer for this question is LocateRegistry.createRegistry(1099 );. Thank you @AlexanderPetrov – MiH Jul 21 '16 at 19:28
It work, but I dont know why when I using command line, it fails. And when I use LocateRegistry.createRegistry(1099 ), it works – MiH Jul 21 '16 at 19:29
In order to make it work form the command line. When you start the registry use the "-classpath" and pass the Jar file containing the server. Got it ? – Alexander Petrov Jul 21 '16 at 19:30
So can you explain what explain createRegistry do, and what difference with command line rmiregistry – MiH Jul 21 '16 at 19:30
The difference is that when you start it from your code your Registry and your Server share the same JVM. So all the server classes are visible to the registry and when you start it from the command line the Registry and the Server are running in to separate JVMs. – Alexander Petrov Jul 21 '16 at 19:32
read this http://stackoverflow.com/questions/9440619/how-do-i-set-the-classpath-that-rmiregistry-uses you need to pass the JAR file holding the server to the Registry. – Alexander Petrov Jul 21 '16 at 19:35
Can u tell me what registry do. Is that Registry will read define of Server's code and creates Stubs ? After then when a Client request, Registry will response a Stub ? – MiH Jul 21 '16 at 19:36
sorry, classpath of my PC, or classpath of my project ? – MiH Jul 21 '16 at 19:37
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/117965/discussion-between-alexander-petrov-and-hng-hip). – Alexander Petrov Jul 21 '16 at 19:37

score 0 · Answer 2 · answered Jul 21 '16 at 19:11

0

You don't have the stub on the CLASSPATH of the Registry. The easy way round this is to start the Registry in the server JVM, via LocateRegistry.createRegistry().

You may then find you don't have it in the client CLASSPATH either.

answered Jul 21 '16 at 19:11

user207421

305,947
44
307
483

But it still error with : java.rmi.ConnectException: Connection refused to host: localhost; nested exception is: java.net.ConnectException: Connection refused: connect – MiH Jul 21 '16 at 19:16
@EJP if you look into my comments I have told him this like 1 hour ago. – Alexander Petrov Jul 21 '16 at 19:27
@AlexanderPetrov You're kidding, right? I should read 60 comments? All I read was your incorrect answer. Good to see you've now fixed it to agree with mine. – user207421 Jul 22 '16 at 00:32
@ejp it is just the 4th out of 50 comments. Anyway it was nice to see you confirming my thoughts though your answer is still partial. – Alexander Petrov Jul 22 '16 at 06:38
@AlexanderPetrov As is yours. There is also the option of starting `rmiregistry` with the `-classpath` option, or from a specific working directory such that the default CLASSPATH of `.` will allow loading of the stub apclasses. I don't consider these to be much practical use, and ditto the codebase feature frankly. – user207421 Jul 22 '16 at 10:11
@EJP see my comment number 7 yesterday. all is there, just don't thing putting the whole server in the registry so a good solution. That is why it is not in my final answer. – Alexander Petrov Jul 22 '16 at 10:18
@AlexanderPetrov I am really not going to read 60, or 55, or 7, or even 4, comments on what at the time was a wrong answer prior to writing my own. Your expectations are misplaced. – user207421 Jul 22 '16 at 10:36

Running RMI Server, got errors with marshalling arguments and class not found

2 Answers2