public partial class MyService : ServiceBase
    {
        private HttpListener _httpListener;

        public MyService()
        {
            InitializeComponent();
        }

        protected override void OnStart(string[] args)
        {
            _httpListener = new HttpListener();
            _httpListener.Prefixes.Add("http://localhost:9999/");

            _httpListener.Start();
            _httpListener.BeginGetContext(Callback, _httpListener);
        }

        private void Callback(IAsyncResult ar)
        {
            try
            {
                var httpListener = (HttpListener)ar.AsyncState;
                var context = httpListener.EndGetContext(ar);

                httpListener.BeginGetContext(Callback, _httpListener);

                var longTimeString = DateTime.Now.ToLongTimeString();
                var buffer = Encoding.UTF8.GetBytes(longTimeString);

                context.Response.ContentEncoding = Encoding.UTF8;
                context.Response.ContentLength64 = buffer.Length;
                context.Response.OutputStream.Write(buffer, 0, buffer.Length);

                context.Response.OutputStream.Dispose();
            }
            catch (Exception ex)
            {
                
                
            }
        }

        protected override void OnStop()
        {
            _httpListener.Stop();
            _httpListener.Close();
        }
}