How to cancel async task via web request?

Question

Here is the scenario: On user login I start a task which is listening to IMAP idle for mail notifications and it has live connection with the client via signalr(kind of push notification). Now the problem is how do i cancel this task? i.e. user cancel push notification or log out..

EDIT: as per my understanding for example if 5 users logged on to the site there are 5 tasks running? so how do i cancel individual tasks.

Answer 1

The asynchronous worker must be modified to support cancellation

http://www.csharp-examples.net/cancel-asynchronous-method/

You could also use the background worker which is a bit less complicated http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.cancelasync.aspx

A problem I have encountered when you send a cancel to an external source (DB, app) which has already started a job, if it does not support canceling, you may have to wait until it finishes.

EDIT: I've never done this with MVC but found a good article on 'Using a Cancellation Token' for an asycn process which takes a CancellationToken parameter in MVC4. http://www.asp.net/mvc/tutorials/mvc-4/using-asynchronous-methods-in-aspnet-mvc-4 hope it helps.