sockets in Prolog

[carlos calderon]

Hi All,

 

I am trying to pass ALL the solutions generated by a prolog "solver" to a server. To test this idea I wrote a small program:

 

go(X,Y) :-

            solve(X,Y),

            client(X,Y).

 

/*where solve yields X and Y taken into account a series of geometrical constraints*/

 

solve(X,Y) :-

            /*Vars, domains and constraints are defined here*/

 

>> This works no problem. It does what's meant to do.

>>Then to send the data to my server I wrote the following

 

client(X,Y) :-

            socket('AF_INET'. Socket),

            socket_connect(Socket, 'AF_INET' ('152.XXX.XXX.XXX', 2000), StreamInput,StreamOutput),

            /*where XXX is the IP address of my server*/

            write_term(StreamOutput, X, []),nl,

            write_term(StreamOutput, Y, []),

            close(StreamOutput). /*close stream*/

 

 

Well, the result I got -looking in the log files- is:

first line: Accepted 1 1 /*the X and Y coordinate of a solution*/

>>however when I tried to generate another solution by keying in ";" The new solution pops up in the prolog side but when the program tries to pass it on to the server I got the following message:

Discarding redundant connection attempt

current socket handle is 360

 

>>I think it's because my client code closes the current output stream when "close(StreamOutput)" is called.

>>then I tried the following:

client(X,Y) :-

            socket('AF_INET'. Socket),

            socket_connect(Socket, 'AF_INET' ('152.XXX.XXX.XXX', 2000), StreamInput,StreamOutput),

            /*where XXX is the IP address of my server*/

            repeat,

            (X==end_of_file

                ->!

            ;

            write_term(StreamOutput, X, []),nl,

            write_term(StreamOutput, Y, []),fail),

            close(StreamOutput). /*close stream*/

 

>>I get an infinite loop. I think because X==end_of_file it's never true.

My question is how can I create a loop in prolog to pass ALL the solutions to the server?

 

I also thought of two possibilities:

 

a)

    1) dump my results to a file

    2) read (from a file) and send (to a server) using a repeat loop

 

b) To be certain that output has been delivered use the following built-in predicate: flush_output/1

 

 

That's all folks, I've been stuck with this for the last day or so.

Please, any help it's greatly appreciated.

If the question has been answered before I apologise but I'd be grateful if someone tells me where the archives of the list are.

 

 

Many thanks,

 

Carlos