This book was very disappointing, for several reasons: Firstly, I find it hard to believe that with the author's supposed years of expertise in this area, he advocates the design approach that is contained in this book - an approach that seems to be at odds with modern commercially-available rules engines. Secondly, he then spends most of the book building a "rules engine" and most of the book seems to be a "how to build" manual for this piece of software, which I can't imagine anyone else ever using. I recommend that anyone interested in rules engines look elsewhere.