IMO, the analogy between Rule Engine and ORDBMS *could* be made with only very simple business rules covering one object (presumably mapped to one table). However you would still need to design mechanisms to support truth maintenance and an activation schedule. Once the complexity of your business rules exceeds even the very simple you will need to implement a whole host of cross-table-triggers to support different objects in a rule (and who knows how complex the business rules will become?). This doesn't even touch upon more advanced features like collect and accumulate. You would be in essence implement a rule engine in a ORDBMS using the ORDBMS triggers and tables as the RETE network nodes. I would compare using a rule engine vs ORDBMS to using say, RichFaces instead of HTML and the XMLHttpRequest object: both can achieve the same result but one is more painful. Drools is free, fast, feature rich and easy to use. Why reinvent the wheel? With kind regards, Mike -----Original Message----- From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Raffi Khatchadourian Sent: 23 April 2008 16:48 To: rules-users Subject: [rules-users] Fundamental Question What is the difference in using a rules engine like drools as opposed to using either an object database or ORDBMS mapping to a database with triggers? _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users