CustomInstanceStore QueryActivatableWorkflowsCommand

Question

I'm currently writing my own Custom Workflow InstanceStore for a WorkflowServiceHost, I found this sample how to implement a Custom InstanceStore:

http://blogical.se/blogs/mikael/archive/2011/02/01/using-appfabric-cache-as-wf-persistence-store.aspx

My problem is now that I also want to load the persisted Workflows on startup and use timers. Is there any documentation or samples about that?

As far as I've come (using ILSpy on SqlWorkflowInstanceStore) I have to create a timer which perodically checks for runnable instances and call InstanceStore.SignalEvent to raise a QueryActivatableWorkflowsCommand  but when I call that method my application crashes (in Debugger) after the command call is finished without a AppDomain.UnhandledException.

Have anybody experience with building a complete Custom InstanceStore?

Answer 1

Ok my problem was that on a seperate thread (Catched by the Visual Studio test Application) I got the exception that the event is unknown. I've done some googling and found this microsoft code:

By some random googling I found the following .NET framework source code:

               if (currentEvent.Name == HasRunnableWorkflowEvent.Value.Name)

                {

                    try

                    {

                        IAsyncResult result = this.instanceManager.BeginGetInstance(Guid.Empty, null, this.instanceManager.Host.PersistTimeout,

                            PrepareAsyncCompletion(handleEndGetInstance), this);

                        return SyncContinue(result);

                    }

                    catch (Exception exception)

                    {

                        if (Fx.IsFatal(exception) || !this.instanceManager.HandleException(exception))

                        {

                            throw;

                        }

                    }

                }

                else

                {

                    Fx.AssertAndThrow("Unknown InstancePersistenceEvent (" + currentEvent.Name + ")!");

                }

Means raising a HasActivatableWorkflowEvent was the wrong idea.

But still, has there anybody made already expiriences writing a custom instance wit loading persisted workflows?

Answer 2

I managed to make the workflows getting loaded but I have following problem with restarting a workflow host:

When I load a persisted workflow and call a correlated operation after the LoadWorkflowByInstanceKeyCommand the workflow gets aborted but imidatly resumed again (I noticed this because I use the tracking parcipiant).

This only happens when I load the workflow using TryLoadRunnableWorkflowCommand. When start a new workflow and call the correlated operation this does not happen.