Translating External Events

Interview Phase (Optional)

When to Interview: Skip if the user has specified: external systems involved, webhook/API formats, and domain mapping. Interview when external systems haven't been fully cataloged or translation rules are unclear.

Interview Strategy: Catalog all external systems and understand their event formats before defining translation rules. Missing correlation strategies — how external IDs map back to domain entities — are the most common source of integration failures, so surface them early.

Critical Questions

1. External System Details (Impact: Determines what translation rules to create)

   • Question: "Which external systems send events? For each: (A) System name, (B) Event types, (C) Data format (JSON/XML), (D) Authentication needed?"
   • Why it matters: Translation rules depend entirely on what the external system sends
   • Follow-up triggers: For each system → ask "Does their payload include your internal entity ID, or do you need a correlation reference table?"

2. Domain Mapping Complexity (Impact: Determines if translation is straightforward or complex)

   • Question: "For the most complex integration: Does the external event data: (A) Map directly to domain concept, (B) Need aggregation/multiple events, (C) Need data from another system to map?"
   • Why it matters: Simple 1-to-1 mappings vs. complex multi-source translations affect design
   • Follow-up triggers: If (B) or (C) → ask "What data must you look up from your own system to complete the translation? How do you handle arrival before that data exists?"