Hi all,

I'm new to RMI and I am having real trouble in invoking remote methods.
I have a server program running on my student server which has Java SDK
1.5.0. I seem to have been down every avenue I can think of yet I still
can't sort it.

The jist is that I can connect to the registry ok but not a remote
method. It consistently shows exception:-

java.rmi.ConnectException: Connection refused to host: 138.37.95.141;
nested exc
eption is:
       java.net.ConnectException: Connection timed out: connect
[abridged here]
-------------------

I run the registry using rmiregistry 30280 and I run the Server as
follows:-

java -Djava.security.manager
-Djava.security.policy=file:/home/cb07/RMI/FileServer/java.policy
-Djava.rmi.server.hostname=138.37.95.141
-Djava.rmi.server.codebase=file:/home/cb07/RMI/FileServer/ FileServer

My policy file shows:-
grant
{
      permission java.security.AllPermission;
};

My client code is:-
---------------------------
import java.rmi.*;
import java.io.*;
import javax.swing.*;

public class FileClient{

   public FileClient(){
       try{
           BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
           /*System.out.println("Enter URL");
           String remoteHost = br.readLine();
           int remotePort = 1099; //default value
           try{
               System.out.println("Enter port");
               remotePort = Integer.parseInt(br.readLine());
           }
           catch(NumberFormatException nfe){
               System.out.println(nfe.toString());
           }*/

           String remoteHost = "students.odl.qmul.ac.uk";
           int remotePort = 30280;

           FileServerInt server = (FileServerInt) Naming.lookup("rmi://"+
remoteHost+ ":" + remotePort + "/FileServer");
           System.out.println("Connected to remote FileServer");
           System.out.println("Enter the string you wish the server to
display");
           String serverString = br.readLine();

           server.printString(serverString);

           JFileChooser fc = new JFileChooser();
           fc.setVisible(true);
           System.out.println("Here");

           //return value is what the user presses in the open File
dialog
           int returnVal = fc.showOpenDialog(null);
           System.out.println("Here");

           //if they choose OK
           if (returnVal == JFileChooser.APPROVE_OPTION) {

                 //file now references the selected
                 File file = fc.getSelectedFile();

                 //create a FileInputStream from file location
                 FileInputStream fis = new FileInputStream(file);
                 // Create the byte array to hold the data, the same size
as the file
                 byte [] fileBytes = new byte[(int)file.length()];
                  // Read in the bytes from the file into the byte array
                  int offset = 0;
                  int numRead = 0;
                  while (offset < fileBytes.length &&
                 (numRead=fis.read(fileBytes, offset,
fileBytes.length-offset)) >=
                 0) {
                     offset += numRead;
                 }
                 // Ensure all the bytes have been read in
                 if (offset < fileBytes.length) {
                     throw new IOException("Could not completely read file
"+file.getName());
                 }
                 fis.close();

                 //File is now read in so send the name of and the byte
array
                 //to the remote object
               server.saveFile(file.getName(), fileBytes);
            }
        }
        catch (Exception e) {
            e.printStackTrace();

        }
   }
   public static void main(String args[]) {
       FileClient client = new FileClient();
   }
}

Server Code
-----------------
import java.io.*;
import java.rmi.*;
import java.rmi.server.*;

public class FileServer extends UnicastRemoteObject implements
FileServerInt {

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

   public void saveFile(String name, byte [] bytes) throws
RemoteException{

       System.out.println("Here");
       try{
           File f = new File(name);
           FileOutputStream fs = new FileOutputStream(f);
            fs.write(bytes);
            fs.close();
        }
       catch(IOException e){
           e.printStackTrace();
       }
   }

   public void printString(String str) throws RemoteException{
       System.out.println(str);
   }

   public static void main(String [] args) throws IOException{

       int portNumber = 1099; //default
       BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
       System.out.println("Enter url");
       String host = br.readLine();
       System.out.println("Enter port number");
       try{
           portNumber = Integer.parseInt(br.readLine());
       }
       catch(NumberFormatException nfe){
           System.out.println(nfe.toString());
       }

        try{
           FileServerInt server = new FileServer();
           Naming.rebind("rmi://" + host + ":" + portNumber + "/FileServer",
server);
        }
        catch(Exception e){
           e.printStackTrace();
           System.exit(0);
        }
        System.out.println("Server listening on port number " + portNumber);
    }
}
-------------------------------------------------------------------------------------------------------------------------------------
In both classes the host name and port are students.odl.qmul.ac.uk and
30280.

Does anybody else have any ideas because I'm at the point of throwing
this damn monitor out of the window?

Regards,

Chris

P.S. If I set the hostname property on the server to a single word
instead of an ip address (i.e. -Djava.rmi.server.hostname=ventus) the
connection to the registry is really quick. Idf I use the ip address it
is really slow (about 15 secs to connect to the remote server).