let main_server serv_fun =
    let port = 2000 in
    let my_address = Unix.inet_addr_any in
    Unix.establish_server serv_fun (Unix.ADDR_INET(my_address, port))

let uppercase_service ic oc = 
    try while true do
        let s = input_line ic in
        let r = String.uppercase s in
        output_string oc (r ^ "\n");
        flush oc
    done with _ ->
        Printf.printf "End of text\n";
        flush stdout;
        exit 0
        
let _ =
    Unix.handle_unix_error main_server uppercase_service