Chalk talk in PDC09 - Future Directions for State Machine Workflows

In PDC this year, PDC2009 in Los Angeles, I got the chance to share with some of you on the future plan on State Machine in a chalk talk presentation, and did a demo of an early prototype with an Order Processing scenario. And I would like to thanks those of you who attended the session and gave valuable feedback.

Thanks Matt Winkler for blogging on the chalk talk, I have received requests from some of you who were not able to attend the session, to share the content of the chalk talk.  And here are the key topics.

The plan

Microsoft will release a NET 4.0 compatible WF State Machine implementation for public review around Visual Studio 2010 release timeframe to solicit more customer feedback and shape the features we plan to ultimately ship.


Flowchart will be released in .NET 4.0 and it enables many free form control flow scenarios, however, it may not provide the way to handle event driven scenarios that a state machine fits naturally.

Major features under discussions

  • Object Model
    • Nested states
    • Query Interfaces
    • Self-transition
    • Event teardown model, etc…
  • Designer
    • Transition UX
    • Expand in place
    • Show evaluation order in conditional transition, etc…

· Feedback

  • We are interested in your scenarios and feature requirements
  • You can continue to give us feedback via forum, connect site or email to me,

And here is a screenshot of the early prototype.  Again, usual disclaimers apply, this is just a prototype for us to share ideas and solicit feedback, the final product may be different and is subject to change, etc…

We will continue to use this blog to share on the work for State Machine, stay tuned!! :)

state machine 2

Alan Ko (

Program Manager (WCF/WF)