Advantages of Rule Engines :
Greater flexibility : keeping your rules into a Knowledge base let you adapt easily your decisions when they are changing.
Easier to grasp : Rules are easier to understand than procedural code so they can be effectively used to bridge the gap between business analyst and developers.
Reduced complexity : When embedding lots of decision points to your procedural codes it can easily turn your application into a nightmare. On the other hand rules can handle much better increasing complexity because they use a consistent representation of business rules.
Reusability : By keeping rules are kept in one place leads to a greater reusability of your business rules. Also, traditional procedural code often impose unnecessary variations of base rules which are therefore more difficult to reuse in other contexts.
