Karl Reinsch’s Blog

My blog stats show trending topics around searches for “wf4 rule engine” and “wf rule engine” among other variations. If those topics are leading people to this blog, then I might as well address the topic directly.

For those who don’t know what the queries above mean – it means that people are searching for the rule engine feature (named Windows Workflow Foundation Rules Engine aka “WF Rules”) in Microsoft’s Windows Workflow Foundation (aka WF). The feature originally shipped with .NET 3.0, and I have written previously about the feature set especially as it compares to Microsoft’s other rules offering.

With .NET 4.0, the Workflow Foundation is introducing a new workflow model (more details here) – so we now talk about WF in .NET 3.0/3.5 as “WF3″ and WF in .NET 4.0 as “WF4″. However, as mentioned at that link, all of WF3 is still available in .NET 4.0.

Now, to the rule engine question. WF4 does not include a new forward chaining rules engine. To be clear, that does not preclude one being made available in the future. A direct statement from Microsoft on the topic can be seen on the .NET Endpoint blog as follows:

“Two other major WF 4 activities that were discussed at PDC, a new state machine activity and a new forward chaining ruleset activity, will not be available with the VS2010 beta 1 release – and we will cover each of these topics in greater depth in the next month. At this point, a new forward chaining rules engine won’t be ready for the .NET 4 timeframe, and will probably see a CTP release post-VS2010 to gather feedback and to allow customers the opportunity to evaluate the direction we are considering. It’s important to note that we are working to ensure integration with the WF 3 rules engine will be possible in a number of ways, though; one example of integration back to the WF 3 rules engine is the SDK sample activity I mentioned above.”

There is also now some rules-specific migration guidance published here as part of some overall WF3->WF4 migration guidance. See also the WF Migration Kit CTP 1 that I posted about previously.

Finally, if you have interest in rules for WF4 and are willing to provide feedback to Microsoft – I encourage you to do so. Questions about using the WF3 rules with WF4 should most likely be addressed via the forums. Specific feature requests for the future should be provided through Connect (detailed instructions for providing feedback about WF4 through Connect). If you are interested in discussing your rules scenarios and requirements in more detail with someone from Microsoft, you can contact me via the contact form on this blog.