Designing event payloads
On This Lesson 4 topics
This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.
In this lesson
choose the content of an event.
Planned topics
- Include:
eventId(unique, for deduplication),type,occurredAt,version(schema), the aggregate ID, and key business data. - Minimal (notification) event: IDs only; consumers call back for details, which adds coupling and load.
- Full-state event: carries the data consumers need; larger, but consumers stay autonomous.
- A middle path: carry the facts that changed or that most consumers need, not entire database rows.
- Evolve schemas compatibly: add optional fields, never reuse or retype fields (schema registry, MID-029).
Draft outline details
Demonstration
{ "eventId": "a1b2...", "type": "OrderPlaced", "version": 1,
"occurredAt": "2026-03-01T10:15:30Z",
"data": { "orderId": "o-42", "customerId": "c-7", "total": "59.90", "currency": "EUR" } }Check your understanding
What is the eventId for?
Show answer
Uniquely identifying the event so consumers can detect duplicates.
Practice
Apply this lesson with the module's lab, exercises and quiz.
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