java.net.ConnectException :connection timed out: connect?

Question

I have used RMI in my code :

 import java.rmi.*;

 public interface AddServerIntf extends Remote {
  double add(double d1,double d2) throws RemoteException;
 }

---

import java.rmi.*;
import java.rmi.server.*;

public class AddServerImpl extends UnicastRemoteObject implements AddServerIntf {
  public AddServerImpl() throws RemoteException {
  }

 public double add(double d1,double d2) throws RemoteException {
  return d1+d2;
 }
}  

---

import java.net.*;
import java.rmi.*;

public class AddServer {
   public static void main(String args[]) {
    try {
     AddServerImpl addServerImpl=new AddServerImpl();
     Naming.rebind("AddServer",addServerImpl);
    }  catch(Exception exc) {
          System.out.println(exc);
       }
   }
}

---

import java.rmi.*;
public class AddClient {
  public static void main(String args[]) {
     try {
       String Url="rmi://"+args[0]+"/AddServer";
       AddServerIntf addServerIntf=(AddServerIntf)Naming.lookup(Url);
       System.out.println("The first number is "+args[1]);
       double d1=Double.valueOf(args[1]).doubleValue();
       System.out.println("The second number is: "+args[2]);
       double d2=Double.valueOf(args[2]).doubleValue();
       System.out.println("The Sum is: "+addServerIntf.add(d1,d2));
     }  catch(Exception exc) {
         System.out.println(exc);
       }
   }
 }

These are 4 .java files written.

Next i compile all these files.Then I create a stub using rmic AddServerImpl. After that i start rmi registry on server side using start rmiregistry. Then i start server using java AddServer and finally client using java AddClient 27.60.200.80 5 9. But nothing happens

Exception that is thrown on client side is java.net.ConnectException : connection timed out : connect

What is the reason and how can i solve this?

On client machine these are the following .class files AddClient.class AddServerImpl.class AddServerImpl_Stub.class and on server side AddServer.class AddServerImpl.class AddServerImpl_Stub.class AddServerIntf.class

Answer 1

The error message says it all: your connection timed out. This means your request did not get a response within some (default) timeframe. The reasons that no response was received is likely to be one of:

• a) The IP/domain or port is incorrect
• b) The IP/domain or port (i.e service) is down
• c) The IP/domain is taking longer than your default timeout to respond
• d) You have a firewall that is blocking requests or responses on whatever port you are using
• e) You have a firewall that is blocking requests to that particular host
• f) Your internet access is down

Note that firewalls and port or IP blocking may be in place by your ISP

Answer 2

Number (1): The IP was incorrect - is the correct answer. The /etc/hosts file (a.k.a. C:\Windows\system32\drivers\etc\hosts ) had an incorrect entry for the local machine name. Corrected the 'hosts' file and Camel runs very well. Thanks for the pointer.

Answer 3

Exception : java.net.ConnectException

This means your request didn't getting response from server in stipulated time. And their are some reasons for this exception:

• Too many requests overloading the server
• Request packet loss because of wrong network configuration or line overload
• Sometimes firewall consume request packet before sever getting
• Also depends on thread connection pool configuration and current status of connection pool
• Response packet lost during transition

Answer 4

If you're pointing the config at a domain (eg fabrikam.com), do an NSLOOKUP to ensure all the responding IPs are valid, and can be connected to on port 389:

NSLOOKUP fabrikam.com

Test-NetConnection <IP returned from NSLOOKUP> -port 389