/* Пример активити
public sealed class CodeActivity1 : NativeActivity
    {
        [RequiredArgument]
        public InArgument<DateTime> left_date { get; set; }
        [RequiredArgument]
        public OutArgument<bool> cancelProg { get; set; }
        protected override void Execute(NativeActivityContext context)
        {
            var d1 = left_date.Get(context);
            if(check)
            {
            }
            else
            {
                ICheckArgumentsNotifier ext = context.GetExtension<ICheckArgumentsNotifier>();
                ext.SendNotification("checkaArgs", d1, d2, "Input incorrect");
                context.CreateBookmark("checkaArgs", new BookmarkCallback(this.OnResumeBookmark));
            }
        }
        protected override bool CanInduceIdle
        {
            get { return true; }
        }
        public void OnResumeBookmark(NativeActivityContext context,Bookmark bookmark,object obj)
        {
            if (obj != null)
            {   var dict = obj as Dictionary<string, object>;
                left_date_out.Set(context, dict["Date1"]);
                right_date_out.Set(context, dict["Date2"]);
            }
        }
    }
//Нотифаер
using System.Threading;
    namespace lab5
    {   public interface ICheckArgumentsNotifier
        {
            void SendNotification(string bookmarkName, DateTime d1, DateTime d2, string message);
        }
        public class CheckArgumentsNotifier : ICheckArgumentsNotifier
        {
            public EventHandler<CheckArgumentsNotifierEventArgs> notify;

            public void SendNotification(string bookmarkName, DateTime d1, DateTime d2, string message)
            {
                if (notify != null)
                    ThreadPool.QueueUserWorkItem(delegate (Object state)
                    { notify(this, new CheckArgumentsNotifierEventArgs(bookmarkName, d1, d2, message)); }); }
        }
        public class CheckArgumentsNotifierEventArgs : EventArgs
        {
            public string BookmarkName { get; private set; }
            public DateTime D1 { get; private set; }
            public DateTime D2 { get; private set; }
            public string Msg { get; private set; }
            public CheckArgumentsNotifierEventArgs(string bname, DateTime d1, DateTime d2, string msg)
            {
                BookmarkName = bname;
                D1 = d1;
                D2 = d2;
                Msg = msg;
            }        }    }


// runwfapp
private void RunWFApp(DateTime date1, DateTime date2)
        {
            AutoResetEvent syncEvent = new AutoResetEvent(false);
            AutoResetEvent idleEvent = new AutoResetEvent(false);
            var inputs = new Dictionary<string, object>() { { "Left_date", date1 }, {"Right_date", date2 } };
            var reason = string.Empty;
            WorkflowApplication wfApp = new WorkflowApplication(new WF(), inputs)
            {
                Completed = delegate (WorkflowApplicationCompletedEventArgs ea)
                {
                    if (ea.CompletionState == ActivityInstanceState.Faulted)
                        reason = ea.TerminationException.Message;
                    syncEvent.Set();
                },
                Aborted = delegate (WorkflowApplicationAbortedEventArgs ea)
                {
                    syncEvent.Set();
                },
                OnUnhandledException = delegate (WorkflowApplicationUnhandledExceptionEventArgs ea)
                {
                    return UnhandledExceptionAction.Terminate;
                }
            };
            CheckArgumentsNotifier notifier = new CheckArgumentsNotifier();
            notifier.notify += delegate (Object sender, CheckArgumentsNotifierEventArgs e)
            {
                var outputs = new Dictionary<string, object>();
                DialogResult dResult = MessageBox.Show(e.Msg, "Произошла ошибка", MessageBoxButtons.OKCancel);
                if (dResult == DialogResult.OK)
                {
                    outputs.Add("Canceled", false);
                    CorrectDataForm form = new CorrectDataForm();
                    form.dateTimePicker1.Value = date1;
                    form.dateTimePicker2.Value = date2;
                    form.ShowDialog();
                    if (form.success)
                    {
                        outputs.Add("Date1", dateTimePicker1.Value.Date);
                        outputs.Add("Date2", dateTimePicker1.Value.Date);
                    }
                    else outputs["Canceled"] = true;
                    wfApp.ResumeBookmark(e.BookmarkName, outputs);
                }
                else
                {
                    outputs.Add("Canceled", true);
                    wfApp.ResumeBookmark(e.BookmarkName, outputs);
                }
            };
            wfApp.Extensions.Add(notifier);
            wfApp.Run();
            syncEvent.WaitOne();
            if (reason != string.Empty) MessageBox.Show(reason);
        }

//кнопка
private async void button1_Click(object sender, EventArgs e)
        {
            if (this.button1.InvokeRequired)
            {
                this.BeginInvoke(new MethodInvoker(delegate
                {
                    this.button1.Enabled = false;
                }));
            }
            else this.button1.Enabled = false;
            await Task.Factory.StartNew(() =>
            { RunWFApp(date1, date2);
            });
            MessageBox.Show("WF Закончен");
        }