How can an activity close itself?
This might be a little bit of a na?ve question. I want to have an activity terminate itself after some activity-determined event. As an example, I tried just using a timer (the real code will be looking for other events besides time). I created the following code (as part of an activity) and can’t figure out how to finish up in the MyTimer_Elapsed. I know my example is wrong and can’t work… the ActivityExecutionContext can’t be saved and used later, but I think using it incorrectly shows better what I’m trying to achieve.
Timer MyTimer =null;
ActivityExecutionContext MyContext;
protectedoverrideStatus Execute(ActivityExecutionContext context)
{
MyContext = context;
MyTimer =newTimer(1000);
MyTimer.AutoReset =false;
MyTimer.Elapsed +=newElapsedEventHandler(MyTimer_Elapsed);
MyTimer.Start();
returnStatus.Executing;
}
void MyTimer_Elapsed(object sender,ElapsedEventArgs e)
{
MyContext.CloseActivity();
}
How do I accomplish this? I’m sure the answer is fairly simple…
I'm aware that I could have used the Delay activity. Essentially, I think, I'm asking how to implement my own "Delay" activity. I don't see how to do that within the current framework, though I'm sure it is possible. I tried messing around with IEventActivity though I couldn't find any documentation on how to use it. I couldn't create a QueueEventArgs object (the class doesn't have a constructor) so I gave up going down that path.
I think I understand the InvokeMethod/EventSink activity pair but I'll have to do some experiments to see if I really do (I haven't tried it yet) but I'm not sure I like this solution. Maybe I can create a custom sequence activity that does this so it can be packaged as a single activity.
The reason I'm attempting to do something like this is that our existing product allows users to generate their own workflows. We currently use a custom workflow system, but we're looking into whether we want to use Windows Workflow as our new workflow system. I want my activity to appear as a single activity in the workflow rather than requiring that the user always create a more complicated workflow with two activities. (One overriding goal in moving to a new workflow system is to make it easier for our customers to create simple workflows and a two-activity approach does just the opposite. This activity will be an essential activity that nearly all our customers will use.).
Thanks for your responses so far.
Steve
Hi,
I tried to use the "SetTimer" method from the ActivityExecutionContext like this:
protected
override Status Execute(ActivityExecutionContext context){
.....
DateTime currentTime = DateTime.Now;
DateTime timerExpiration = currentTime.AddSeconds((double)SecondsTimeout);
context.SetTimer(timerExpiration, new EventHandler<EventArgs>(ActivityTimedout));
... ...
return Status.Executing;
}
However, no matter what large value I set to "SecondsTimeout", the timer handler "ActivityTimedout" is always called by the workflow runtime immediately, resulting in canceling out the activity too soon. Why? The only idea I could think of is that may be I did not register the in-memory timer service to the workflow runtime?
Thanks for any helps,
Jiebo
I got it work. The problem was in the way I set up the timer. Instead of getting current time using DateTime.Now, which gets the local time, getting current time using DateTime.UtcNow worked.
Jiebo
