Subscribe to commercetools Change Messages via a Subscription to track order state changes in an event-driven integration

Steps

1. Create a Subscription via POST /subscriptions with a destination (e.g., AWS SQS or Google Cloud Pub/Sub) specifying credentials and queue URL/topic ARN
2. Set the messages array to include the resourceTypeId (e.g., order) and specific types like OrderStateChanged, OrderLineItemAdded to filter noise
3. Validate the subscription is active by reading it back — commercetools will send a test message to the queue on creation; confirm it arrives to verify connectivity
4. In your consumer, parse the message envelope: check type to distinguish ResourceCreated, ResourceUpdated, and specific message payloads; use the sequenceNumber to detect out-of-order delivery
5. Handle at-least-once delivery: use the id field of each message as an idempotency key and store processed IDs to skip duplicates