Basic RMI

[Cyril Sadasivan]

I have just started trying out RMI..
I have the Server class and Client class on different machines. rmiregistry was started on Server machine. properties were set using jndi.properties files at server and client

for the below Java code :

service:

import java.rmi.*;
import java.rmi.server.*;
public class Greeter extends UnicastRemoteObject implements RemoteGreeter{
	public Greeter() throws RemoteException{}
	public String sayHello(){return "Hello";}
}

remote interface :

import java.rmi.*;
public interface RemoteGreeter extends Remote{
	public String sayHello() throws RemoteException;
}

server:

import javax.naming.*;
public class Server{
	public static void main(String... args){
		try{
			Greeter greeter=new Greeter();
			Context context=new InitialContext();
			context.rebind("greetHello",greeter);
		}catch(Exception exception){
			exception.printStackTrace();
		}
	}
}

properties file at server:
java.naming.factory.initial=com.sun.jndi.rmi.registry.RegistryContextFactory
java.naming.provider.url=rmi://localhost:1099

client:

import javax.naming.*;
public class Client{
	public static void main(String... args){
		try{
			Context context=new InitialContext();
			RemoteGreeter greeter=(RemoteGreeter)context.lookup("greetHello");
			System.out.println(greeter.sayHello());
		}catch(Exception exception){
			exception.printStackTrace();
		}
	}
}

properties file at client:
java.naming.factory.initial=com.sun.jndi.rmi.registry.RegistryContextFactory
java.naming.provider.url=rmi://120.61.40.49:1099

i get the below error when i run the Client class:

javax.naming.ServiceUnavailableException [Root exception is java.rmi.ConnectExce
ption: Connection refused to host: 120.61.40.49; nested exception is:
java.net.ConnectException: Connection timed out: connect]
at com.sun.jndi.rmi.registry.RegistryContext.lookup(Unknown Source)
at com.sun.jndi.rmi.registry.RegistryContext.lookup(Unknown Source)
at javax.naming.InitialContext.lookup(Unknown Source)
at Client.main(Client.java:6)
Caused by: java.rmi.ConnectException: Connection refused to host: 120.61.40.49;
nested exception is:
java.net.ConnectException: Connection timed out: connect
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(Unknown Source)
at sun.rmi.transport.tcp.TCPChannel.createConnection(Unknown Source)
at sun.rmi.transport.tcp.TCPChannel.newConnection(Unknown Source)
at sun.rmi.server.UnicastRef.newCall(Unknown Source)
at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
... 4 more
Caused by: java.net.ConnectException: Connection timed out: connect
at java.net.TwoStacksPlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(Unknown S
ource)
at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(Unknown S
ource)
... 9 more


Can anyone suggest what i am doing wrong?

[rohit chavan]

Hi,

Are you able to ping the server IP (i.e. 120.61.40.49) from client machine?

[Cyril Sadasivan]

Hi Rohit,

I did ping the server machine. But I see the IP address has changed.

G:\client>ping 120.61.112.250

Pinging 120.61.112.250 with 32 bytes of data:

Reply from 120.61.112.250: bytes=32 time<1ms TTL=254
Reply from 120.61.112.250: bytes=32 time<1ms TTL=254
Reply from 120.61.112.250: bytes=32 time<1ms TTL=254
Reply from 120.61.112.250: bytes=32 time<1ms TTL=254

Ping statistics for 120.61.112.250:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

But there was no luck with the Java program