How to connect UCI chess engine even to web-browser on windows locally

This post is more related to programming / not chess. Anyway, it can be useful for connection to UCI interface chess engines. As we know, there are GUIs as Arena, xboard, winboard, etc. to use strong chess programs as Rybka, stoskfish and others. The basic idea (how it's realized) is redirection of stdin-stdout streams, that is input/output of chess engine .exe file. Nothing has changed so long since DOS times, windows based applications use the same starting and managed-capturing of sub-process controls. Nowadays sometimes it's not so convenient if we want to connect high level platforms with great chess features what strong chess programs provide. It is so, because chess programs are long-time-projects made for chess, not for latest social networks nor tweets or youtubes. The solution described here is a ready connector to DOS console based application even from browser. Software development platforms can do HttpRequests by default nowadays and that's enough to run any UCI chess engine on

Windows by using this simple tool (download).

Now about how it's made:

There is an app ExeConnector.exe that should be started. This:
1. starts a local webserver (others can access from outside internet too by http://<your-ip>, be careful, set firewall on this port or don't set it if You want it so);
2. starts a chess engine (DOS application, developed in C,C++ usually) with redirected input/output streams of this program - to/from this webserver;
3. waits for HTTP: requests, sends browser-request based answers;
4. closes all and releases memory after request with "EXIT_EXE" as data.


*NOTES
1.Tool is for Microsoft Windows only.
2.Framework 2 pre-installed as minimum required (can be newer, any normal windows has it already)
3. If You don't know, http://localhost/ is the same as http://127.0.0.1/
4. In downloadable version just cmd.exe as sample provided, so You can get directory structure in browser by:

http://localhost:5050/OUT_BUFFER.txt?OUT_BUFFER=dir c:*.*
http://localhost:5050/IN_BUFFER.txt

Download the chess engine You want and use the same way.
5. Or the best sample is Unity3D chess project where 3D objects love requesting deep chess searches.

TUTORIAL:

ExeConnector.exe is a console application to call as a process, or from command line shell once on starting of serving.

Parameters in Data\ folder.
Put the exe-file name in Exe2Start.dat
Command line arguments write in Arguments.dat (better not to do it, because stdin-stdout redirected, use method below), just in case.
Provide port number to interract with web server for local socket requests in port.dat

For tests:

1.Start ExeConnector.exe and send data to STDIN of this EXE by (DATA SEND)

http://localhost:5050/OUT_BUFFER.txt?OUT_BUFFER=position fen 7k/Q7/2P2K2/8/8/8/8/8 w - - 0 70\ngo depth 10\n

*08.11.2011 modified processing to command ,pause, command,...

2.Wait few seconds and get STDOUT from exe (actually best move in given chess position) through browser by (REQUEST)

http://localhost:5050/IN_BUFFER.txt

Possibly requests for each uci command should be separated (depends on chess engine).

3. At the end of all requests send command to exit processes and close all by

http://localhost:5050/OUT_BUFFER.txt?OUT_BUFFER=EXIT_EXE

There is a developed code for Stockfish chess engine connection to 3D javascript in browser and even battling possibilities with Cuckoo java chess engine. Can play strong chess. Browser is like a GUI for engine and a player controller capturer for javascript based chess board to battle vs other chess engine automatically.
Unzip this archive on desktop and start the .bat file.


For implementation in other EXEs above (for example Unity3D calls in C#):

Start processes by :

using System.Diagnostics;
using System.Net;

try
{
p=new Process();
p.StartInfo.WorkingDirectory = Path;        // directory of stockfish chess engine
p.StartInfo.CreateNoWindow = true;
p.StartInfo.FileName = ExeFileName;        // stockfish.exe for example...
p.StartInfo.Arguments = "";
p.StartInfo.UseShellExecute = false;
p.Start();
}
catch(Exception e) {}        //if unable to start process...

And read or send to local sockets as http: requests by

HttpWebRequest request = WebRequest.Create("http://localhost:5050/IN_BUFFER.txt") as HttpWebRequest;
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
StreamReader reader = new StreamReader(response.GetResponseStream());
String buffer=reader.ReadToEnd();
reader.Close();
}

Of course, You can now connect it via PHP

$contents=file_get_contents('http://localhost:5050/IN_BUFFER.txt');

or python:

import urlib.request
response = urlib.request.urlopen('http://localhost:5050/IN_BUFFER.txt')
html = response.read()

or by using Http-Requests in javascript,
or any other programming language so used today.

And do not do this if You have no clue what is written here about.


*03.03.2014 There is a DLL library named ExeHandler (for Win32 applications) functions of which can start exe-processes, define stdin/stdout as strings and get output results. Samples for usage in QB64 or Visual FoxPro are listed in readme file.
 

*jan.2021 Added a houdini version here. Take a look at FreeBasic chess project, how it works with chess engines. There are FreeBasic web servers too. In case, connecting to FICS servers, I used the cmd PuTTY tool in connection to apps or a web-server, see a Unity project. Sockets programming is quite tricky, so it's good to have ready solution. Set up a small-any-platform php-server, chess engine, make a middleware between them.

*apr. 2024 Added ExeHandler64 win64 version with Flutter usage sample.