Guidelines for implementing a rule engine

Question

What could be the reasons to implement your own rule engine instead of using an existing commercial/open source one? Any specific guidelines for implementing rule engines?

Answer 1

See this post for argument for implementing your own:

Rules Engine - pros and cons

mainly the problem centers around the anemic data model anti-pattern. as described here:

http://martinfowler.com/bliki/AnemicDomainModel.html

How you should implement depends very much on the requirements but generally important points to consider when designing your own include.

• Make the ability to add rules dynamic. So you don't have to shut down the system to edit rules.
• Match the rules syntax to the appropriate user level, don't expect a secretary to be writing SQL.
• Take advantage of your domain knowledge to implement your domain models which you will run your rules against.
• Drools is a good bit of software, try to learn lessons from how that was implemented.
• Try to modularize your rules engine so it functions independent of any business process tools you might be using