TriggeredEvaluationFunction

Challenge :

The situation where an implementation of the EvlauationFunction is done only to watch out for changes on a specific channel value is a common one. This leads to the requirement for a default structure that already has the logic needed to recognize changes on channel values of interest.

Soulution :

The TriggeredEvaluationFunction. It can watch the values on channels and trigger a result extraction, when the set condition is met. There for that implementation has the following members as a tool set:

• TriggerStrategy : This is a class, that holds the rules on when to trigger a result creation processing.
• EventExtractor : This class creates resulting Events, when processing is triggered by the TriggerStrategy.
• EventFilter : This class finally filters the resulting Events from the EventExtractor, so that only relevant Events are passed to the next stage in processing.

Code Example :

TriggerEvaluationFunction function = new TriggerEvaluationFunction.Builder()
            // set the trigger strategy
            .withTriggerStrategy(TriggerStrategies.onBecomeTrue())
            // set the event extractor
            .withEventExtractor(Extractors.valuesExtractor("U", "I", "T"))
            // set the filter (optional)
            .withFilter(EventFilters.onValueChanged(Suppliers.doubleChannel("T")))
            .build();