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    Does DMN spell the end of the "rules engine"?

    Mark Norton  30 April 2015 05:34:28 p.m.
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    Does DMN spell the end of the "rules engine"?

    Paul Vincent

    Consultant, Isvana Ltd

    DMN transformations to decision services does not require any tradition "rules engine"! There is no inferencing implied in DMN (arguably DMN could be simplified to exploit inferencing, but no one is asking for that). Incremental development is no longer a big deal (so interpreted rules engines or declarative rules languages as targets are less important), although rapid prototyping of data models might drive a requirement. So does DMN mean the end of the rules engine?

    Case in point: the Sapiens DECISION (TDM modelling) tool I've been using can generate decision services via rules engines or Java. But if there are no restrictions on the Java implementation, the question (as asked by a slightly offended vendor in one customer meeting) is "then what is the role of the rules engine now?"...

    Mark Norton

    CEO and Founder, Idiom Ltd

    Hi Paul, this is a timely question.
    Most rules requirements are intended to execute within commercial transactions.
    The rete algorithm was never intended for use in a transactional context, as per the final comments of Forgy’s original rete paper:
    “Certainly the algorithm should not be used for all match problems . . . Since the algorithm maintains state between cycles, it is inefficient in situations where most of the data changes on each cycle.”
    Transactions use a new set of data for each transaction (by definition), so Rete was always the wrong solution for transactional problems. The target use cases for rete and procedural implementations are mutually exclusive.
    This topic is discussed more fully here. http://www.modernanalyst.com/Resources/Articles/tabid/115/ID/2713/Decisioning-the-next-generation-of-Business-Rules.aspx
    Regards, Mark