Function evaluate_dmn_decision 

pub async fn evaluate_dmn_decision(
    configuration: &Configuration,
    workspace: &str,
    evaluate_request: EvaluateRequest,
) -> Result<EvaluateResponse, Error<EvaluateDmnDecisionError>>

Evaluate a saved decision (decision_id, no inline xml) or an inline document (xml, with decision_id optional). These two cases use decision_id differently: when evaluating a stored decision, decision_id is purely the storage path used to load the XML, not a selector into it. For inline xml, decision_id doubles as an in-document <decision id> selector, since the storage path and the document’s internal decision id are unrelated namespaces. To select a specific decision inside the document explicitly – including a non-first decision in a saved multi-decision document – supply decision_ref, which is always the in-document selector regardless of branch. An archived stored decision cannot be evaluated (400).