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Operaton DMN Compatibility Checklist

A practical checklist for authoring DMN files that deploy and execute correctly in Operaton (the open-source Camunda 7 CE fork). Work through this list when a DMN fails to deploy or produces unexpected results.

1) Namespace and DMN version

  • ✅ Use DMN 1.3 namespace: xmlns="https://www.omg.org/spec/DMN/20191111/MODEL/"
  • ✅ Avoid DMN 1.1 namespace — Operaton supports 1.1 but behaviour may differ for newer features
  • ✅ Verify <definitions> has a valid namespace attribute and a unique id

2) Decision IDs and references

  • ✅ Every <decision> element must have a unique id attribute
  • ✅ <requiredDecision href="#..."> must reference the id of another <decision> in the same <definitions>, not its name
  • ✅ <informationRequirement> elements need their own unique id attribute
  • ✅ Avoid duplicate id values anywhere in the document — even across <dmndi:DMNDI> elements

3) FEEL expressions

  • ✅ Use not(x) — not not x (the latter is a unary test, not a negation function)
  • ✅ Unary test intervals: [a..b), (a..b], [a..b] — parentheses for exclusive bounds
  • ✅ and / or in unary tests refer to multiple unary conditions on the same input — do not use them as Boolean operators in FEEL expressions
  • ✅ String literals must use double quotes: "active", not 'active'
  • ✅ Date literals: date("2026-01-01"), not bare strings
  • ✅ Test FEEL expressions in isolation with the Operaton REST API evaluate endpoint before deploying a full DRD

4) Variable naming and types

  • ✅ Use simple variable names (letters, digits, underscore). Avoid spaces and punctuation in variable names referenced by FEEL.
  • ✅ In FEEL, reference runtime variables (the <variable name="...">) rather than element IDs
  • ✅ Keep numeric types consistent — Integer vs Double differences between request and DMN declaration cause runtime type errors

5) Null / missing inputs

If a required input may be absent, Operaton may throw a runtime error rather than producing a null output.

  • ✅ Use null-safe FEEL where inputs may be missing: x = false is safer than not(x) when x can be null
  • ✅ Use if x = null then … else … for optional inputs
  • ✅ For optional inputs, provide defaults in FEEL expressions: if medischeVerklaring = true then true else missendeMaand = false

6) DMNDI (diagram section)

The engine ignores the <dmndi:DMNDI> block for execution, but the Operaton Modeler and UI use it for rendering.

  • ✅ Avoid multiple DI elements referencing the same dmnElementRef
  • ✅ <dmndi:DMNEdge> dmnElementRef must reference an <informationRequirement> ID, not a <decision> ID
  • ✅ If deployment fails and you cannot isolate the cause, temporarily remove the entire <dmndi:DMNDI>…</dmndi:DMNDI> block, deploy without it, and re-add once the execution logic is confirmed working

7) Operaton-specific extensions

  • ✅ If Operaton enforces history cleanup TTL, set camunda:historyTimeToLive="..." on <decision> elements (or configure a global default in the engine)
  • ✅ Keep extension namespaces consistent: xmlns:camunda="http://camunda.org/schema/1.0/dmn"

8) Deployment debugging workflow

If you see ENGINE-22004 Unable to transform DMN resource …:

  1. Verify DMN namespace and version (DMN 1.1 vs 1.3)
  2. Check for broken href="#..." references — the target id must exist
  3. Check FEEL parsing: not x vs not(x), unary test and/or vs Boolean and/or
  4. Temporarily remove <dmndi:DMNDI> to rule it out
  5. Inspect Operaton server logs immediately after ENGINE-22004 for the underlying parse error — the 22004 message is a wrapper; the actual cause is one line below it

9) Testing strategy

  • ✅ Test leaf decisions first (single-input literal expressions) before testing a full DRD
  • ✅ When testing a decision that depends on others, provide the full upstream input set — unless you have made all inputs null-safe
  • ✅ Maintain one "superset" JSON payload covering all possible inputs for the chain, usable for quick regression testing across DMN versions