How to Build a Business Rules Engine

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In the previous chapter subtypes were used in the context of relationships. However,

rule types that do not involve relationships can also use subtypes. The components

of these rules all come from a single table, and we shall consider an example in this

chapter. This again highlights the importance of subtypes when dealing with busi-

ness rules.

Another aspect of business rules that is not widely appreciated is that if rule types

are very specific for the business they support, it becomes possible to associate

business-specific metadata with rules. This opens up many new possibilities for man-

aging information within business rules engines that are very difficult to implement

in other design approaches.

Calculate A Fee

The rule type that we shall consider ...