Major problems with networking client.

[Mark O' Sullivan]

Hi,
Firstly I'm just running project locally.
I'm having major issues with networking client. I have the GUI set-up correctly.
First thing I'm finding is that when I input the client ip address, the method getByAddress(address) from the "java.net.InetAddress" package will return the valid TCP connections that exist. So for example:
I input 0.0.0.0 and tcp connection already exists on machine, this will return as valid.
Same if I input 127.0.0.1, this will return as valid, so if the server is running as 127.0.0.1, and client tries to connect using 0.0.0.0, the application currently crashes.
Is 1 suppose to write the server ip address and port in the shared configuration file?
If so, how does 1 obtain the server ip address in rmi when binding the remote object?
I'm questioning this, because if multiple say 127.0.0.1 and multiple 0.0.0.0 tcp connections already exist, they will be seen as obtaining valid addresses by the method getByAddress(address).

[Johnny Barbosa]

Hi,

I do a ping to check if the IP is correct. Like this:

InetAddress ping = InetAddress.getByName(host);
if(ping.isReachable(3000)) {
    return;
 }
throw new UnknownHostException();

[Roberto Perillo]

Howdy, Mark!

Champion, I'm not really sure if I got your question... but, from the server perspective, you should only have to write the database location in the configuration file. The client that wants to connect to it must have the server IP address and port number in which the service is running before connecting to it.

[K. Tsang]

Hi Mark, have you try outputting that ip address on the server - InetAddress.getHostAddress() or something? It should not be 127.0.0.1 but 192.168.x.x for LAN.

Also if you entered 127.0.0.1 on the client to connect to the server then it WILL ONLY connect to 127.0.0.1 and not localhost. Same for the other way. If you use host name to connect (eg localhost) then entering the IP will not work.

I recommend you use the ip version because changing servers is simpler.

[Mark O' Sullivan]

Hi,
I will update the problem I'm facing here. Any help very much appreciated.
Firstly I am running both client and server on same machine, and using port 1099.
Here is code I use to register the HotelReservationImpl object:

  public static void register(String dbLocation, int rmiPort)
            throws RemoteException {
    	Registry r = java.rmi.registry.LocateRegistry.createRegistry(rmiPort);
        // make a dvd database instance on a random port and register
        // our service name and our port number on the RMI registry.
    	r.rebind("HotelReservator", new HotelReservationImpl(dbLocation));
    	
     }

and here is code I use to look up object:

public static HotelReservationDB getRemote(String host,int port)
            throws RemoteException {
    	System.out.println("\nThe host name is " + host + " the port number is " + port);
    	String url = "rmi://" + host + ":" + port + "/HotelReservator";
    	try{
    	HotelReservationDB hotelReservation
        = (HotelReservationDBRemote) Naming.lookup(url);
    	return hotelReservation;
            } catch (NotBoundException e) {
                System.err.println("HotelReservator not bound: "
                        + e.getCause());
                throw new RemoteException("HotelReservator not bound: ", e.getCause());
            } catch (java.net.MalformedURLException e) {
                System.err.println(host + " not valid: " + e.getMessage());
                throw new RemoteException("cannot connect to " + host, e);
            }
    	
    }

Using the following code to resolve the hostname to ip address and storing as string:

InetAddress inetAddress = InetAddress.getByName(databaseLocation);
serverAddress = inetAddress.toString();

I presume this is ok.
So therefore the System.out.println, when I try and look up object results in;
The system.out.println is printing “The host name is localhost/127.0.0.1 the port number is 1099”
I presume this is ok.
But I'm getting a bound exception, clearly "Naming.lookup" isn't working.
"HotelReservator not bound: null"
I thought It might be the fact I haven't generated the HotelReservationImpl stub but I have, maybe it can't find it, using eclipse by the way. I know it should automatically but I did again just in case.
I wonder could it be an issue with the way the database is stored in properties file, I'm using windows:
I think this is ok, entry is saved when server starts as DatabaseLocated=D\:\\eclipseProjects\\MarksProjects\\db-1x2.db
Localhost is 127.0.0.1. I have also included the server images before and after it starting.
Any help must appreciated.

[K. Tsang]

Hi Mark,

If Naming.lookup() isn't working try using LocateRegistry.getRegistry(address, port).

Also depending on how you bind your server, the hostname or ip must match on the client.