Subscription Processing

[jasoneisen]

User story
As a client, I want Subscriptions to push notifications to their specified channel (rest-hook/websocket/email/sms/message) based on their specified criteria. Retries, error handling, and status changes should be applied with sane defaults.

https://hl7.org/fhir/R4/subscription.html

Acceptance criteria

1. For an active Subscription, changes to resources that meet the Subscription criteria trigger a notification via the specified channel.
2. Failed notifications should be retried with sane defaults.
3. Undeliverable notifications should trigger a change in Subscription status to error.

[valeneiko]

I have an implementation for rest-hook with custom datastore (#1117) based on SQL, which uses hangfire to periodically run search queries from subscriptions and send notifications.

Some implementation details

• When Subscription resource is created, parse criteria using logic from SqlSearchService and create a SQL Stored Procedure with that query (and additional filter on ResourceSurrogateId to query a selected time window)

• Periodically find subscriptions that match the target resource type from the subscription criteria, by searching if any resources of that type were created / updated since last check (configurable, by default every 1 min)

• Schedule a job for every matching subscription

  • Execute a query from subscription criteria (Stored Procedure) to find matching updated resources
  • Send rest-hook notification to the endpoint

I was planning to submit a PR, but will not have time to do this in the next 3 months. I am happy to push the existing (working) implementation (using Postgre and based on old commit f20c5b2) if anyone would find this useful.

[joshmouch]

Are there plans to implement the Subscription feature described here? Or perhaps the FHIR R5 version of the Subscription feature?

[rwolfdev]

Is there a plan to support the subscription feature?

[EXPEkesheth]

We have the item in our backlog. There is no ETA determined yet.