Re: Socket communication between GNU prolog and Java.

[Ugoretzc]

I have followed your suggestions and made these modications to the two programs:

THE JAVA PROGRAM:
import java.io.*;
import java.net.*;

public class JavaToGP2
{
    public static void main(String s[]) {
    try {
        Socket socket=new Socket("localhost", 27311);       
        PrintWriter out= new PrintWriter(socket.getOutputStream(), true);
        BufferedReader in= new BufferedReader(new InputStreamReader(socket.getInputStream()));
            out.println("hello.");
            String line;
            while ((line = in.readLine()) != null) {
                System.out.println(line + "\n");
            }
            
            out.close();
            in.close();
            socket.close();
    }
    catch (Exception e) {
        System.err.println("JavaToGP error: "+e.getMessage());
    }     
    }
}

THE GNU PROLOG PROGRAM:
gui_create_server(Port):-
    gui_create_server(localhost,Port).

gui_create_server(Host,Port):-
    catch((socket('AF_INET',NbSocket),
           socket_bind(NbSocket,'AF_INET'(Host,Port)),
               socket_listen(NbSocket,5),
               socket_accept(NbSocket,I,O),
           add_stream_alias(I, input_stream),
           add_stream_alias(O, output_stream)),
          X,write(X)).
gui_create_server(_,_):- gui_disconnect.

gui_disconnect:-
    catch(close(input_stream),_,true),
    catch(close(output_stream),_,true),
    abort.
gui_disconnect:- abort.

    
serve_data:- gui_create_server(27311),
         catch(read(input_stream,R), X, write(catch(X))),
         write('READ '), write(R), nl, flush_output.

I attempted to follow more strictly the format of the CLPGUI program (in fact I copied snippets of it nearly exact, except for socket_accept/4, which I reduced to socket_accept/3 to avoid an error).  When I run the server, and then the client, I get the following error:

error(system_error(Invalid argument),socket_accept/3)catch(error(existence_error(stream,input_stream),read/2))READ _71

I am using a different Windows 98 computer than the one I previously wrote these programs for (see earlier email), but the system error is still the same.