How is it right to challenge the event from the flow?

[Laycee]

There's a facility A (the event manager) that has a flow that occasionally triggers this event. There's an object B that's signed for the event and receives data from A. When B processs the event, there's an exception as if class B is working in the flow of A, is that normal? I fixed it through SynchronizationContext, but can there be better options?

[Avante]

Events at NET are delivered in the same flow as those produced. If you need to deal with another flow, there are several ways:

1. Get the challenge in the right context. https://msdn.microsoft.com/en-us/library/hh199422%28v=vs.110%29.aspx ♪ https://msdn.microsoft.com/en-us/library/system.windows.forms.control.begininvoke%28v=vs.120%29.aspx ♪ https://msdn.microsoft.com/en-us/library/system.threading.synchronizationcontext.post%28v=vs.110%29.aspx , depending on the type of your application.

   Example:

   void OnEvent(object sender, EventArgs args)
   {
       Control.BeginInvoke((Action)(() => OnEventReally(sender, args)));
   }
   

   async void OnEvent(object sender, EventArgs args)
   {
       await Dispatcher.InvokeAsync(() => OnEventReally(sender, args));
   }
   

2. Go to Reactive Extensions and use it. https://msdn.microsoft.com/en-us/library/hh229634%28v=vs.103%29.aspx :

   Observable.FromEventPattern<EventArgs>(sender, "EventName")
             .ObserveOn(SynchronizationContext.Current)
             .Subscribe(ev => { ... });
   

3. Move to async processors and deliver the implementation in the right context with help RedirectToas described in https://ru.stackoverflow.com/a/458425/10105 (samare, yes).

   async void OnEvent(object sender, EventArgs args)
   {
       await AsyncHelper.RedirectTo(Dispatcher);
       ...
   }