Workflow Foundation is single threaded (one thread at a time will run your workflow instance, but the workflowRuntime is multithreaded : several workflows can run simultaneously), even when we use the ParallelActivity which coordonates execution
of activities in multiple branches in a round-robin fashion; this doesn't mean the same thread will always run the workflow instance: indeed, if we use the DelayActivity (or if the workflow wait for another kind of message), the running thread is released and after the delay, another thread can be used to run the workflow.

This is true even in a TransactionScopeActivity !!!

By the way, you need to know that if you use the SqlWorkflowPersistenceService with the flag UnloadOnIdle set  to true, if your workflow becomes idle in the middle of a TransactionScope activity, your workflow WON'T BE PERSISTED. There is a tight coupling between the TransactionScopeActivity (TSCA) and the workflowRuntime which prevents it to be persisted & unloaded; the workflowRuntime also gives a higher priority to the child activities of the TSCA and this has an impact if we have a TSCA in one branch of a ParallelActivity and a Sequence activity in the other branch of the ParallelActivity.

 

 

 

 

 

the last 2 weeks have been very busy : I've prepared the OBA Train the Trainer session that I had to teach last week in Paris for Microsoft.

This course has  been created by Patrick Tisseghem for Microsoft.

OBA means Office Business Application (see: www.obacentral.com and Office Business Application Portal) and that is really what I like : building real applications from existing building blocks like Office client, .Net, Sharepoint, Open XML and several nice patterns.

Very exiting was the fact that some members of the OBA team (Redmond) like Joanna Bichsel and John Graham attended my course (see picture below).

Thank you all for attending this Oba session. My next Oba session will probably take place in China next month (my first trip in China).

In the meantime, I'll continue my work with MS learning to finalize the Windows Workflow Foundation (beta) certification exam.

On the other side, I have many many scenarios in mind about using  Workflow Foundation in OBA apps, I'd really need to work 30 hours a day.

And this week, I'll be in Denmark  to teach a Sharepoint course for U2U...