Lately I have been assigned to work with the Windows Workflow Foundation.
My feelings about it are mixed. There was a bug, that hold me for one day and I want to share with you, a troubleshooting technique that helped me.
First of all, out runtime service need to be persisted. In order to test persistance with Workflow out of the box activities, just create a while (true) activitiy with a seqeunce activity with a delay and something that can be debugged. I have create a Debug Activity.
The runtime is initialized with an sql persistance service like this
NameValueCollection persistenceParams = new NameValueCollection(); persistenceParams.Add("ConnectionString", ConnectionString); persistenceParams.Add("UnloadOnIdle", Convert.ToString(true)); persistenceParams.Add("LoadIntervalSeconds", "5"); this.runtime.AddService(new SqlWorkflowPersistenceService(persistenceParams));
Every time a delay or a timer is reached because of UnloadOnIdle, it will be persisted.
My problem was that the workflow never resumed although, the entries in the database were correct.
I monitored its flow, by capturing these events
But WorkflowLoaded never came through. The reason I know it should was because I was actually refactoring I knew the sequence of events that would be fired.
Finally, and after some time I decided to capture ServicesExceptionNotHandled event. It turns out that although you may have declared to capture all exceptions form Visual Studio (Ctrl+Alt+E), if you do not capture that event you will never know what’s wrong.
The event provides a ServicesExceptionNotHandledEventArgs that basically holds the exception of what wen’t wrong.
In my case the problem was with serialization. The actual problem I will discuss in my next post.