State Machine Frameworks for .NET

Question

We have a system at my work that is basically a message-driven state machine. It takes in a variety of types of messages, looks up some context/state based on the message, then decides what to do, based on the message and the current state. Normally the result is a message being sent out of the system.

Are there any good open-source frameworks for implementing a state machine in .NET? I've looked into the latest release of Windows Workflow, and it seems like it would be a good option; however, I have some concerns about the default persistence mechanisms (we need to report off the state transition data), testability, and the fact that the WF team is re-architecting the framework as we speak (supposedly).

Instead of WF, I'm thinking of trying to implement a plain-old GoF "State" pattern, and using Spring.NET to wire everything together. Is there anything out there that already does this, or something similar?

Answer 1

Depending on your exact requirements you might find the State Machine Compiler is sufficient for implementing the GoF "State" pattern. It can generate C# as well as dot which can be transformed into several image formats using Graphviz. I've used it on a previous project and found it sufficient for generating a 'simple' state machine. I hope this helps.

Answer 2

I maintain an open-source project which implements (among other things) a generic finite state machine for .NET. It is built on top of QuickGraph, so you get many graph-analysis algorithms for free. See this page for more information.