Conflict between socket and RMI

Question

Hi
I wrote a program in client-server using socket and it was fine. I also wrote a client-server program using RMI. Fine as well. But after I connected the client-server using socket (open socket, send-receive messages, close socket), then use RMI. I got java.rmi.NotBoundException.
Would anyone have a look and provide your feedback please? Thanks.
big J
*****************this is Server.java ***************************
package single;
import java.io.*;
import java.rmi.Naming;
import java.rmi.RemoteException;
import java.net.*;
import java.rmi.*;
public class Server
extends Thread {
public static final int SOCKETPORT = 5555;
private String serverName;
public Server() throws IOException {
System.out.println("*** socket opened ***");
serverName = new String("localhost");
ServerSocket serverSocket = new ServerSocket(SOCKETPORT);
Socket socket = serverSocket.accept();
InputStream is = socket.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(is));
System.out.println(bufferedReader.readLine());
OutputStream os = socket.getOutputStream();
PrintWriter printWriter = new PrintWriter(new OutputStreamWriter(os), true);
printWriter.println("from server");
os.close();
is.close();
socket.close();
System.out.println("*** socket closed ***");
public void runServer() {
System.out.println("*** start of run():RMI ***");
System.setSecurityManager(new SecurityManager());
try {
RMIInterfaceImpl rMIInterfaceImpl = new RMIInterfaceImpl();
Naming.bind("//" + serverName + ":9999/RMIInterface", rMIInterfaceImpl);
catch (RemoteException ex) {
catch (MalformedURLException ex) {
catch (AlreadyBoundException ex) {
System.out.println("*** end of run():RMI ***");
public static void main(String args[]) throws Exception {
Server server = new Server();
server.runServer();
******************this is Client.java **************************
package single;
import java.io.*;
import java.net.*;
import java.rmi.Naming;
public class Client {
private String serverName;
private final static int SOCKETPORT = 5555;
public Client() throws IOException {
serverName = new String("localhost");
Socket socket = new Socket(serverName, SOCKETPORT);
OutputStream os = socket.getOutputStream();
PrintWriter printWriter=new PrintWriter(os, true);
printWriter.println("from client");
InputStream is = socket.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(is));
System.out.println(bufferedReader.readLine());
is.close();
os.close();
socket.close();
public void runClient() throws Exception {
System.out.println("*** start of runClient():RMI ***");
System.setSecurityManager(new SecurityManager());
RMIInterface rMIInterfaceImpl = (RMIInterface) Naming.lookup(
"//" + serverName + ":9999/RMIInterface");
String str = rMIInterfaceImpl.print();
System.out.println(str);
rMIInterfaceImpl.serverSide();
System.out.println("*** end of runClient():RMI ***");
public static void main(String args[]) throws Exception {
Client client = new Client();
client.runClient();
***************** this is RMIInterface.java ***********************
package single;
import java.rmi.Remote;
import java.rmi.RemoteException;
interface RMIInterface
extends Remote {
String print() throws RemoteException;
void serverSide() throws RemoteException;
********************* this is RMIInterfaceImpl.java ***************
package single;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
public class RMIInterfaceImpl
extends UnicastRemoteObject
implements RMIInterface {
public RMIInterfaceImpl() throws RemoteException {}
public String print() {
return new String("hello world");
public void serverSide(){
System.out.println("this should appear in serverside");

Answer 1

I think you have a timing problem between your client and server. As soon as your client and server programs have finished their socket communication, they will both do their "runServer"/"runClient" methods. If the client attempts to lookup the server before the server has registered itself via Naming.bind(), I would expect that's why you're getting a NotBoundException in the client.
You probably wouldn't use the design of your test client/server for something significant, but a quick and dirty way to make this work might be to have the client call Thread.sleep() for a few seconds before trying to do the lookup.