In FHIR R4, topics are discovered by looking at the server CapabilityStatement for the SubscriptionTopic Canonical Extension.

For this walkthrough, we will be using the included encounter-complete topic that has a canonical URL of http://example.org/FHIR/SubscriptionTopic/encounter-complete. The current metadata for this server can be viewed here, or requested (in FHIR) at https://subscriptions.argo.run/fhir/r4/metadata .

Note that in FHIR R4, there is not an official required format for representing SubscriptionTopic resources. Since topics are canonical resources, the expectation is that they will be defined by authors (e.g., in Implementation Guides) and communicated out-of-band. For example, for an "encounter-start" topic, both the server and client can function with only the canonical URL and the understanding of what that topic represents.

With that said, one possible way of representing topics in FHIR R4 is to use the model provided in FHIR R5, ported using FHIR cross-version support. This implementation supports topics defined via that mechanism. Our included encounter-complete topic is thus available on this server at Basic/encounter-complete or in FHIR at https://subscriptions.argo.run/fhir/r4/Basic/encounter-complete .

In this step, we are configuration the subscription options.

The following options are fixed for this walkthrough and are displayed only for reference:

The following options are selected in this walkthrough:

The final piece of configuration for a subscription are filter values. In this tour, we will be using Patient/example as a patient filter for our topic. Note that allowed filters are defined by each topic.

With our configuration complete, we are ready to create our resource and request it on the server.

Waiting for handshake.

The topic we are using is set to trigger when an Encounter is set to the status of finished. This can be true either when the encounter resource is create, or it could be updated from another state.

Since we specified the filter that encounters need to have a patient that matches Patient/example, we need to also set the subject reference to that patient.

For simplicity during this walkthrough, we will create an encounter with all the values needed to trigger a notification.

Waiting for notifications...

That completes this tour. If you have any questions, comments, or suggestions for this software, please let us know. A link to the GitHub repository for this project can be found on the top right corner of the screen.

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