public HttpResponseMessage Post(Hello message)
        {
            if (message == null)
                throw new HttpResponseException(Request.CreateErrorResponse(HttpStatusCode.BadRequest, "You must supply a hello message."));

            string id = Guid.NewGuid().ToString();

            _helloMessages.Add(id, message.Message);
            var response = Request.CreateResponse(HttpStatusCode.Created, message.Message);
            var link = Url.Link("DefaultApi", new { controller = "Hello", id = id });
            response.Headers.Location = new Uri(link);
            return response;
        }
        public HttpResponseMessage Put(string id, Hello message)
        {
            if (message == null)
                throw new HttpResponseException(Request.CreateErrorResponse(HttpStatusCode.BadRequest, "You must supply a hello message."));

            _helloMessages[id] = message.Message;

            var response = _helloMessages.ContainsKey(id) ?
                Request.CreateResponse(HttpStatusCode.Created, message.Message) :
                Request.CreateResponse(HttpStatusCode.NoContent);

            var link = Url.Link("DefaultApi", new { controller = "Hello", id = id });
            response.Headers.Location = new Uri(link);
            return response;
        }