I am experimenting with the scala dmn-engine. I very much appreciate that it appears to be pluggable into Camunda BPMN.
<dependency>
<groupId>org.camunda.bpm.extension.dmn.scala</groupId>
<artifactId>dmn-engine</artifactId>
<version>1.9.0</version>
</dependency>
Questions:
- The code below allows me to use it from Java 21, however, I don’t see how I can find out which matching rule provided the result. The Audit$DecisionTableEvaluationResult internally has a matchedRules attribute, but it appears to be private.
public class DmnDecision {
DmnEngine engine = new DmnEngine.Builder().build();
public Object evaluate(InputStream dmnModel, String decisionId, Map<String, Object> context) {
Either<DmnEngine.EvalFailure, DmnEngine.EvalResult> either = engine.parse(dmnModel)
.flatMap(dmn -> engine.eval(dmn, decisionId, context));
return switch (either) {
case Right<DmnEngine.EvalFailure, DmnEngine.EvalResult> right when right.value().isNil() ->
Map.of(decisionId, null);
case Right<DmnEngine.EvalFailure, DmnEngine.EvalResult> right -> {
Audit.AuditLog auditLog = right.value().auditLog();
Audit.AuditLogEntry entry = auditLog.entries().apply(0);
// no access to matchedRules here?
yield Map.of(decisionId, right.value().value());
}
case Left<DmnEngine.EvalFailure, DmnEngine.EvalResult> failure
-> Map.of(decisionId, failure.value());
default -> throw new IllegalStateException("Unexpected value: " + either);
};
}
}
