C# – Looking for simple rules-engine library in .NET


Does anyone know of a good .NET library rules library (ideally open-source)? I need something that can do nested logic expressions, e.g., (A AND B) AND (B OR C OR D). I need to do comparisons of object properties, e.g., A.P1 AND B.P1. (Ideally, I could compare any property — A.P1 AND B.P2).

It should store the rules in a database (I've got a lot of simple configurable logic). And it should have a rule creation/management API. The management tool would have to inspect the instances to determine which properties are available and which constraints exist.


Oh, one more thing. As a rules-engine, I need to include the concept of Actions (Commands). These are what execute when the expression returns:

If (expression.Evaluation) { actions.Execute(); }

So I see a rule as something like:

class Rule
    Expression Exp;
    Actions[] Actions;
            foreach(action in Actions) 

Best Solution

Agreeing with will I would say use something from the workflow engine family although not workflow. Examine System.Workflow.Activities.Rules Namespace a little bit - it's supported in .Net 3, and built into .Net3.5. You have everything in hand for free to use like you mentioned :

  • RuleCondition for conditions , RuleAction for actions

  • standardized format for describing metacode (CodeDom - CodeExpressions)

  • you can plugin any kind of complexity into that (to tell the truth except Linq and lambdas and so extension methods of some kind) via TypeProviders

  • there's a builtin editor for rule editing with intellisense

  • as the rule is serializable it can be easily persisted

  • if you meant to use the rules over a database scheme then via typeprovider it can be implemented too

For a starter : Using rules outside of a workflow

Ps.: we're using it extensively and there're much more in that namespace than you ever imagine -> a complete meta algorithm language

And the most important : it's easy to use - really

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