problem in start up my RMI server(under ISP) so that it can recieve remote calls over Internet.

Question

i m creating a Client/Server application in which my server and client can be on the same or on different machines but both are under ISP.

My RMI programs:-

-Remote Intreface:-

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

public long sub(long a, long b) 
    throws java.rmi.RemoteException; 

public long mul(long a, long b) 
    throws java.rmi.RemoteException; 

public long div(long a, long b) 
    throws java.rmi.RemoteException; 

}

Remote Interface Implementation:-

//CalculatorImpl.java
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; 
} 

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

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

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

}

Server:-

//CalculatorServer.java
 import java.rmi.Naming;
 import java.rmi.server.RemoteServer;
 public class CalculatorServer {

  public CalculatorServer(String IP) 
  {
    try {

         Calculator c = new CalculatorImpl();

         Naming.rebind("rmi://"+IP+":1099/CalculatorService", c);
        } catch (Exception e) 
          {
            System.out.println("Trouble: " + e);
          }
  }

     public static void main(String args[]) {
     new CalculatorServer(args[0]);
   }
}

Client:-

//CalculatorClient.java

 import java.rmi.Naming; 
 import java.rmi.RemoteException; 
 import java.net.MalformedURLException; 
 import java.rmi.NotBoundException; 

  public class CalculatorClient { 

  public static void main(String[] args) { 
    try { 
       Calculator c = (Calculator)Naming.lookup("rmi://"+args[0]+"/CalculatorService"); 

        System.out.println( c.sub(4, 3) ); 
        System.out.println( c.add(4, 5) ); 
        System.out.println( c.mul(3, 6) ); 
        System.out.println( c.div(9, 3) ); 
    } 
    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); 
    } 
} 

}

when both Server and client programs are on same machine:-

i start my server program by passing my router static IP address:-192.168.1.35 in args[0] and my server starts...fine.

and by passing the same Static IP address in my Client's args[0] also works fine.

but:-

when both Server and client programs are on different machines:-

now,i m trying to start my Server Program by passing it's public IP address:59.178.198.247 in args[0] so that it can recieve call over internet.
but i am unable to start it.

and the following exception occurs:-

Trouble: java.rmi.ConnectException: Connection refused to host: 59.178.198.247;
nested exception is:
    java.net.ConnectException: Connection refused: connect

i think it is due to NAT Problem because i am under ISP.

so,my problem is that how can i start my RMI Server under ISP so that it can recieve remote calls from internet????

Answer 1

Presumably your ISP is blocking the connection. You'll have to talk to them.

Answer 2

Try to see if your port (1099) is visible (you can use this for example). If not, use an open port, or edit your firewall or router configuration (you might need to set up port forwarding). If it is, look into your RMI security policy.