API for the Exchange of Medicinal Product Information (APIX)
0.1.0 - ci-build International flag

API for the Exchange of Medicinal Product Information (APIX), published by HL7 International / Biomedical Research and Regulation. This guide is not an authorized publication; it is the continuous build for version 0.1.0 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/APIX---API-Exchange-for-Medicinal-Products/ and changes regularly. See the Directory of published versions

SubscriptionTopic

Page standards status: Informative

SubscriptionTopic

A SubscriptionTopic defines the event types that a FHIR server is capable of monitoring and notifying subscribers about. While a Subscription represents an individual client’s request to receive notifications, the SubscriptionTopic describes the server‑side triggers that determine when those notifications occur.

Clients use SubscriptionTopics to understand:

  • What kinds of events the server supports (e.g., Task creation, Task status change)
  • What filters may be applied (e.g., by Task.identifier or Task.owner)
  • How the server evaluates whether an event matches a trigger

A Subscription must reference a SubscriptionTopic by its canonical URL. For example, a Subscription that notifies on Task.status changes will reference the SubscriptionTopic that defines the status‑change trigger and its associated FHIRPath criteria.

Example SubscriptionTopic Task status update

Example SubscriptionTopic Task creation, filtered by owner

Key Elements of the APIX SubscriptionTopic Resource

Element Cardinality (APIX) Value / Example Purpose / Notes
SubscriptionTopic.url 1..1 Canonical URL
e.g. http://myfhir/fhir/SubscriptionTopic/TaskStatusChangeWithIdentifierFilter		 Unique identifier used by Subscriptions to reference this topic; must be stable and globally resolvable
SubscriptionTopic.resourceTrigger 1..* • resource = Task
• supportedInteraction = create or update
• fhirPathCriteria = e.g. %previous.status != %current.status		 Defines the events the server monitors and the conditions under which a notification is generated
SubscriptionTopic.canFilterBy 0..* • filterParameter = identifier or owner
• filterDefinition = FHIR SearchParameter URL		 Specifies which filters clients may use when creating Subscriptions for this topic
SubscriptionTopic.name, .title, .description 1..1 (name)
0..1 (others)		 Human‑readable metadata
e.g. “Task Status Change With Identifier Filter”		 Provides descriptive context for implementers and UI presentation