WF4 delay/ resume in WorkflowServiceApplication on IIS5 and 6

Question

I have my workflow hosted in a WorkflowServiceApplication running on IIS5 (production environment will be IIS6) with a persistence database. It's a request/approval service so there's a delay (a few days) whilst waiting for approval and if that delay passes with no approval the workflow sends an e-mail to the approver. I've noticed that the pending workflows only "wake up" and send their e-mails if I kick off a new request (i.e. new workflow instance). I assume that in starting a new flow something checks the instance store for instances that are due to resume and resumes them. I've only just noticed the problem because I was previously testing with delays that were just a few minutes rather than days. I haven't tried it on IIS6 yet but I expect it would be the same.

q1) do I need to write a console app or something to periodically check and resume the flows and if so can someone advise how to do it? Or have I just done something wrong?

q2) Assuming that the answer to Q1 is "yes, you need to write something" if I was to use IIS7 and AppFabric (which may be possible) would the sleep/resume just work without me having to write any code to check and resume the flows? i.e. just deploy the workflow service into AppFabric and it works?

Thanks in advance.

Answer 1

The answer to q1 is yes. After an IIS AppDomain recycles it is not restarted until there is an external request for it. As a result the WorkflowServiceHost is not active and expired Delay activities will not be resumed. With versions of IIS before 7 you need to create an external request to make sure the WorkflowServiceHost is available. The easiest way of doing so is just have a windows service periodically retrieve the WSDL page.

If your upgrade to IIS7 and AppFabric you can configure a service to automatically start as soon as IIS is running and that will take care of the same problem. I would prefer this option as AppFabric gives you a lot of extra benefits like tracking.

Answer 2

Yes Windows Server AppFabric's Workflow Management Service will wake up workflows with pending timers. You get this for free as well as other goodies.