Implement FHIR R4 Subscription backport for real-time resource change notifications
domain: hl7.org/fhir/uv/subscriptions-backport · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Create a Subscription resource using the R4 backport profile, specifying the topic canonical URL in the criteria element using the backport extension
Configure the channel type to rest-hook and supply a secure HTTPS endpoint URL as the channel endpoint
Handle the handshake notification sent by the server at subscription activation to confirm the endpoint is reachable
Process incoming event notifications by parsing the notification Bundle, identifying the subscription event number from the bundle entry parameters, and retrieving referenced resources
Implement idempotent processing using the event number to detect and handle duplicate or out-of-order deliveries
Known gotchas
R4 backport uses the SubscriptionTopic concept expressed via an extension on the Subscription.criteria; servers that only implement native R4 Subscription (topic-less) will not honor these extensions
Notification Bundles may be empty (heartbeat) or contain only resource IDs without full content; the payload content type (full-resource, id-only, empty) is negotiated at subscription creation and must match the consumer's processing logic
The server may deactivate a subscription if delivery fails repeatedly; implement a monitoring check on Subscription.status and reactivate or recreate the subscription when it transitions to 'error'
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