Scesim fails to execute decision service from included model

[dschulten]

Describe the bug

I run the following scenario simulation:

Kostenkennwerte pro Gebaeudeart.scesim.xml

Against this model:
Kostenkennwerte pro Gebaeudeart.dmn.xml

which includes 2 models:

Basiskostenkennwert.dmn.xml

Korrekturfaktor Gebaeudegroesse BGF.dmn.xml

The scesim Junit Test

@TestScenarioActivator
public class TestScenarioJunitActivatorTest {

}

fails:
Error invoking function 'Basiskostenkennwert Service' on node 'Basiskostenkennwert Service'

Internally, a NPE occurs:

"java.lang.NullPointerException: Kie DMN API parameter 'model' cannot be null."

whose stacktrace points to:

org.kie.dmn.core.impl.DMNRuntimeImpl#evaluateById

It appears that the scesim testrunner somehow is unable to execute DMN Services from included models.

When I run the same service as a Spring Boot Rest Service, the DMN Service evaluates the expression just fine. Also, the sandbox happily delivers the expected result Kostenkennwert: 825

### POST Kostenkennwert 4.1 mit Korrekturen
POST {{host}}:{{port}}/KostenkennwerteProGebaeudeart
Content-Type: application/json

{
  "Gebäudeart": "Mehrfamilienhäuser",
  "Gebäudetyp": "mit bis zu 6 WE",
  "Weitere Merkmale": null,
  "Gebäudestandard": 3,
  "Angepasster Basiskostenkennwert": {
    "wert": null
  },
  "Abweichende Dachgeometrie": {
    "prozent": null
  },
  "Gebäudegröße BGF": {
    "flaecheQm": null
  },
  "Durchschnittliche Wohnungsgröße": {
    "flaecheQm": null
  },
  "Grundrissart": {
    "grundrissart": null
  },
  "Zweifamilienhaus": null
}

Expected behavior

The JUnit scesim Runner should come to the same results as the actual DMN Rest Service and the Sandbox.

Actual behavior

The scesim Runner treats included models differently.

How to Reproduce?

See above

Output of uname -a or ver

No response

Output of java -version

openjdk version "21.0.9" 2025-10-21 LTS OpenJDK Runtime Environment Corretto-21.0.9.10.1 (build 21.0.9+10-LTS) OpenJDK 64-Bit Server VM Corretto-21.0.9.10.1 (build 21.0.9+10-LTS, mixed mode, sharing)

GraalVM version (if different from Java)

No response

Kogito version or git rev (or at least Quarkus version if you are using Kogito via Quarkus platform BOM)

10.2.0

Build tool (ie. output of mvnw --version or gradlew --version)

No response

Additional information

No response

[yesamer]

Correct, at this moment Scesim Engine doesn't support DMN Decision Services.

[dschulten]

Correct, at this moment Scesim Engine doesn't support DMN Decision Services.

Well that clears things up :-)
Does this also apply to BKMs from included models?

[yesamer]

Most likely

[dschulten]

It turns out that DMNInvocationEvaluator seems to invoke BKMs properly in 10.2.0, as the following scesim proves:
https://github.com/apache/incubator-kie-kogito-runtimes/blob/main/drools/kogito-scenario-simulation/src/test/resources/importedDMNInputsDecisions/Using%20Imported.scesim

The test has been moved after 10.2.0 to https://github.com/apache/incubator-kie/blob/main/kogito-drools/kogito-scenario-simulation/src/test/resources/importedDMNInputsDecisions/Using%20Imported.scesim.

Interestingly, there is also a variant of the same test in https://github.com/apache/incubator-kie/tree/main/drools-scenario-simulation/drools-scenario-simulation-integrationtest

The DMNInvocationEvaluator has special handling for imported models.
The DMNDecisionServiceEvaluator however does not. Will try to create a PR based on the import handling in DMNInvocationEvaluator, hoping that fits the general approach best.

There are two projects that deal with scenario simulation, incubator-kie/kogito-drools/kogito-scenario-simulation and incubator-kie/drools-scenario-simulation? I guess the former is bound to be deleted at some point, it only contains the deprecated KogitoJunitActivator annotation.