public ActionResult <List <LocationMap> > Message()
        {
            var list = service.GetAll();

            Response.ContentType = "text/event-stream";
            var bytes = Encoding.UTF8.GetBytes(string.Format("data: {0}\n\n", JsonConvert.SerializeObject(list)));

            Response.Body.Write(bytes);
            Response.Body.Close();
            return(list);
        }