gistfile1.cs

    public class VotingController : TaskAsyncController
    {
        static TaskCompletionSource<bool> hasNewVote = new TaskCompletionSource<bool>();

        // Could load this from a DB
        static Question question = new Question {
            QuestionText = "What's your favourite upcoming technology?",
            Answers = new List<Answer> {
                new Answer { AnswerId = 1, AnswerText = "C# 5" },
                new Answer { AnswerId = 2, AnswerText = "WebSockets" },
                new Answer { AnswerId = 3, AnswerText = "Windows 8" },
                new Answer { AnswerId = 5, AnswerText = "Magic rainbow unicorns" },
            }
        };

        public ActionResult Index()
        {
            return View(question);
        }

        public void SubmitVote(int answerId)
        {
            question.Answers.Single(x => x.AnswerId == answerId).NumVotes++;
            hasNewVote.SetResult(true);
            hasNewVote = new TaskCompletionSource<bool>();
        }

        public Task<JsonResult> GetUpdatedState()
        {
                return hasNewVote.Task.ContinueWith(_ =>
                {
                    return Json(question);
                });
        }
    }