Java Prolog Sockets

[Dominique]

I am trying to communicate to a prolog server from a java client,
however even though the connection is successfully made every time I
try to perform QueryExecute I get an error, either Socket closed or
null etc. Can anyone help? I am using SICStus prolog.

Currently my prolog server looks like:
:- write('starting '),nl.
:- use_module(libr ary(sockets)).
:- use_module(libr ary(prologbeans )).
:- use_module(libr ary(charsio)).
start_server(Po rt, QueueLength) :-
socket('AF_INET ', Socket),
socket_bind(Soc ket, 'AF_INET'(local host, Port)),
socket_listen(S ocket, QueueLength),
loop(Socket).

loop(Socket) :-
socket_accept(S ocket, Client, Stream),
on_exception(RE , get_request(Str eam, Request),
h1(Stream,Clien t,RE)),
on_exception(PE , process(Request , Stream, Client), h1(Stream,
Client, PE)),
loop(Socket).

get_request(Str eam, Request):-
read(Stream, Request).

process(bye, Stream, _Client) :-
close(Stream).
process(Request , Stream, Client) :-
on_exception(E, user:applicatio n_handle(Reques t,Result),
h2(Stream, no, E)),
return(Stream,R esult),
on_exception(RE , get_request(Str eam, Request1),
h1(Stream,Clien t,RE)),
on_exception(PE , process(Request 1, Stream, Client), h1(Stream,
Client, PE)).

return(Stream,R esult) :-
nonvar(Result), !,
format(Stream, "~w~n", [Result]),
flush_output(St ream).
return(_, _).

h1(Stream, C, E) :-
format(Stream, "error~n",[]),
format(user_out put, "Client: ~w~nError: ~w",[C, E]).

h2(Stream, Ack, E) :-
format(Stream, "~w~n",[Ack]),
format(user_out put, "Applicatio n Error: ~w~n",[E]).
evaluate(C,R):- R is C.

and my java client looks like:

import java.awt.*;
import java.awt.event. *;
import javax.swing.*;
import java.lang.Objec t.*;
import java.lang.Runti me.*;
import java.lang.Proce ss.*;
import java.lang.*;
import java.awt.*;
import java.applet.*;
import java.util.Stack ;
import java.awt.event. *;
import java.io.*;
import java.util.Strin gTokenizer;
import java.net.*;
import java.beans.*;
import se.sics.prologb eans.*;
import java.nio.channe ls.SocketChanne l;

public class EvaluateGUI implements ActionListener {

private JTextArea text = new JTextArea(20, 40);
private JTextField input = new JTextField(36);
private JButton evaluate = new JButton("Evalua te");
private PrologSession session = new PrologSession() ;

public ServerSocket srv;
public Socket soc;

public EvaluateGUI() {
JFrame frame = new JFrame("Prolog Evaluator");
Container panel = frame.getConten tPane();
panel.add(new JScrollPane(tex t), BorderLayout.CE NTER);
JPanel inputPanel = new JPanel(new BorderLayout()) ;
inputPanel.add( input, BorderLayout.CE NTER);
inputPanel.add( evaluate, BorderLayout.EA ST);
panel.add(input Panel, BorderLayout. SOUTH);
text.setEditabl e(false);
evaluate.addAct ionListener(thi s);
input.addAction Listener(this);
session.setPort (1363);
session.setHost ("192.168.0.84" );
session.setAuto Connect(true);
/*try{

srv = new ServerSocket(13 63,10);
soc = srv.accept();
}
catch(Exception e)
{
System.out.prin tln("Socket exception");
}
*/
try{
session.connect ();
System.out.prin tln("connected" );
System.out.prin tln(session.get Timeout() + " time out");
}
catch(Exception e)
{
System.out.prin tln("Exception thrown");
}
//frame.setDefaul tCloseOperation (JFrame.EXIT_ON _CLOSE);
frame.pack();
frame.setVisibl e(true);
}

public void actionPerformed (ActionEvent event) {
try {
//session.setAuto Connect(true);i nput.getText()

Bindings bindings = new Bindings().bind ("E",
input.getText() + ".");
System.out.prin tln("after bindings " + bindings);

if (session.isConn ected())
System.out.prin tln("IT IS CONNECTED");
else
System.out.prin tln("IT IS NOT CONNECTED");

String myquery = "evaluate(E,R)" ;

QueryAnswer answer = session.execute Query(myquery,
bindings);
System.out.prin tln("after answer " + bindings);

if (session.isConn ected())
System.out.prin tln("IT IS CONNECTED");
else
System.out.prin tln("IT IS NOT CONNECTED");
/*
Term result = answer.getValue ("R");
System.out.prin tln("after term");
if (result != null) {
text.append(inp ut.getText() + " = " + result + '\n');
input.setText(" ");
} else {
text.append("Er ror: " + answer.getError () + "\n");
}
*/
} catch (Exception e) {
text.append("Er ror when querying Prolog Server: " +
e.getMessage() + '\n');
}
finally{

session.disconn ect();
}
}

public static void main(String[] args) {
new EvaluateGUI();
}
}