defining rules engine

Easy Rules provides two implementations of the RulesEngine interface:

• DefaultRulesEngine: applies rules according to their natural order (which is priority by default).
• InferenceRulesEngine: continuously applies rules on known facts until no more rules are applicable.

Create a rules engine

To create a rules engine, you can use the constructor of each implementation:

RulesEngine rulesEngine = new DefaultRulesEngine();

// or

RulesEngine rulesEngine = new InferenceRulesEngine();

You can then fire registered rules as follows:

rulesEngine.fire(rules, facts);

Rules engine parameters

Easy Rules engine can be configured with the following parameters:

Parameter	Type	Required	Default
rulePriorityThreshold	int	no	MaxInt
skipOnFirstAppliedRule	boolean	no	false
skipOnFirstFailedRule	boolean	no	false
skipOnFirstNonTriggeredRule	boolean	no	false

• The skipOnFirstAppliedRule parameter tells the engine to skip next rules when a rule is applied.
• The skipOnFirstFailedRule parameter tells the engine to skip next rules when a rule fails.
• The skipOnFirstNonTriggeredRule parameter tells the engine to skip next rules when a rule is not triggered.
• The rulePriorityThreshold parameter tells the engine to skip next rules if priority exceeds the defined threshold.

You can specify these parameters using the RulesEngineParameters API:

RulesEngineParameters parameters = new RulesEngineParameters()
    .rulePriorityThreshold(10)
    .skipOnFirstAppliedRule(true)
    .skipOnFirstFailedRule(true)
    .skipOnFirstNonTriggeredRule(true);

RulesEngine rulesEngine = new DefaultRulesEngine(parameters);

If you want to get parameters from your engine, you can use the following snippet:

RulesEngineParameters parameters = myEngine.getParameters();

This allows you to reset the engine parameters after its creation.