RMI,can't get connect two computers.

[Robson Martinz]

I am noob in RMI and the material on the Internet is kind of hard to understand because the examples are all on the same computer which is odd, since the main purpose of the RMI is another. I tried to implement the server in a computer, and the client on another computer and follow the codes as below:

What is wrong ?

Computer 1 ->Server:
http://pastebin.com/q5p1PPgp

Computer 2-> Client:
http://pastebin.com/uH3pqBqv

Thanks.

[Pat Farrell]

RMI is a poor choice if the two computers are on the general internet. It is rare for systems on the Internet to have the necessary ports open for RMI communications.

You may want to read my thread:
http://www.coderanch.com/t/570237/java/java/Why-there-still-interest-lots

In general, RMI is no longer a good choice for general problems. It was occasionally useful back in the 1990s, but there are simply too many problems to justify using it.

Use something like REST over normal HTTP.

[Darryl Burke]

Please BeForthrightWhenCrossPostingToOtherSites
http://www.java-forums.org/advanced-java/60365-rmi-cant-get-connect-two-computers.html
https://forums.oracle.com/forums/thread.jspa?messageID=10372062 (currently down for maintenance)

[Robson Martinz]

I'm sorry, I'm trying to solve this problem a long time so I decided to try in other forums as well.
I'll put my source code here and the exception to. I don't know what i'm doing wrong, need solve this for a college work.

Computer 1 Server i put this code:

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

public interface Inter_Mensageiro extends Remote {

    void enviarMensagem(String msg) throws RemoteException;

    String lerMensagem() throws RemoteException;

}
*********************************************************************************
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;

public class Impl_Mensageiro extends UnicastRemoteObject implements Inter_Mensageiro {

    public Impl_Mensageiro() throws RemoteException {
        super();
    }

    @Override
    public void enviarMensagem(String msg) throws RemoteException {
        System.out.println(msg);
    }

    @Override
    public String lerMensagem() throws RemoteException {
        return "Ola mundo meu ovo!";
    }

}
*********************************************************************************
import java.rmi.Naming;
import java.rmi.registry.LocateRegistry;

public class MensageiroServer {
    public static void main(String[] args) {
        try {
            Impl_Mensageiro m = new Impl_Mensageiro();
            LocateRegistry.createRegistry(1099);
            Naming.bind("//192.168.1.100/MensageiroService", m);
            System.out.println("Server working.");
        } catch (Exception e) {
            System.out.println("Erro no servidor: " + e);
        }
    }
}
*********************************************************************************

Computer 2 Client i put this code:

*********************************************************************************
//Same interface that i have in my server computer.
*********************************************************************************
//Same class that implements interface that i have in my server computer
*********************************************************************************
import java.rmi.RemoteException;
import java.rmi.Naming;

public class MensageiroCliente {

    public static void main(String[] args) {
        try {
            Inter_Mensageiro m = (Inter_Mensageiro) Naming.lookup("//192.168.1.100/MensageiroService");
            String resposta = m.lerMensagem();
            System.out.println("Resposta do Server: " + resposta);
        }  catch (RemoteException e) {
            System.out.println();
            System.out.println("RemoteException: " + e.toString());
        }  catch (Exception e) {
            System.out.println();
            System.out.println("Exception: " + e.toString());
        }
    }
}
*********************************************************************************

Error message:
RemoteException: java.rmi.ConnectException: Connection refused to host: 127.0.1.1; nested exception is:
java.net.ConnectException: Connection refused

Thank You.

[Pat Farrell]

Robson Martinz wrote:Error message:
RemoteException: java.rmi.ConnectException: Connection refused to host: 127.0.1.1; nested exception is:
java.net.ConnectException: Connection refused

Either your RMI service is not running, so it could not make the connection, your your computer's operating system firewall is preventing the connection.
If its the firewall, then you will have to reconfigure the firewall.

The problem of firewall ports used by RMI can not be solved in a commercial or enterprise environment. That is the biggest problem with trying to use RMI, and why the technology is dead, and has been dead all of this century.

[Robson Martinz]

I'm using in both computers Linux Mint with Javac 1.6.0_20.
What do i have to do to know if RMI service is running?