Incremental and Non-Incremental evaluation instead of sequential mode. ---------------------------------------------------------------------- Key: DROOLS-2962 URL: https://issues.jboss.org/browse/DROOLS-2962 Project: Drools Issue Type: Feature Request Reporter: Mark Proctor Assignee: Mario Fusco Labels: MDP_BRAINFARTS While Drools supports sequential mode at the engine configuration level. We should move this to a unit and rule level. We should enhance this work too. Right now Drools evaluation is either fully incremental or non-incremental if the kbase is set to stateless. Sequential mode current means two things. 1) Rules evaluate and fire in load order. 2) Rules are non-incremental. By default now all rules are load order anyway. If we simply supported a @NonIncremental or @Incremental(NO) attribute on a unit, then it's behaviour would be the same as sequential is now, but scoped to the unit. I believe this is true, but I'd like this verified (challenged). As with existence/data driven, this is the default for the unit's rules. A unit may override with the opposite configuration. This means a unit can be mixed incremental and non-incremental. Existence or Data Driven annotations for non-incremental do not make sense, and their combination should throw an error, as explained below. Instead a non-incremental rule should have control on whether it is to be re-evaluated and fired, each time the unit is entered. At first glance this behaviour looks very similar to Existence Driven, however the choice not to allow @ExistenceDriven + @NonIncremetal is due to the lack of symmetry. You could not combined @DataDriven + @NonIncremental. That lack of symmetry may break intuitive learning, if it's not kept clean. If an alternative annotation is introduced - such as @OneShot|@EvalAndFireOnce|etc. We should make sure it fits intuitively and cleanly with how we explain @ExistenceDriven.