NxBRE is the open-source rule engine for the .NET platform and a lightweight Business Rules Engine that supports two different approaches:
- The Inference Engine, which is a forward-chaining (data driven) deduction engine and that supports concepts like Facts, Queries and Implications and like Rule Priority, Mutual Exclusion and Precondition (as found in many commercial engines). It is designed in a way that encourages the separation of roles between the expert who designs the business rules and the programmer who binds them to the business objects.
- The Flow Engine, which uses XML as a way to control process flow for an application in an external entity. It is basically a wrapper on C#, as it offers all its flow control commands (if/then/else, while, foreach), plus a context of business objects and results. It is a port of JxBRE to .NET's C#.
NxBRE is released under LGPL license in order to allow users to legally build commercial solutions that embed NxBRE.
Source: .Net Adventures