Pub/Sub notifications

This page provides an overview of using Pub/Sub to receive notifications when clinical events occur in a Cloud Healthcare API data store. To learn how to set up and use Pub/Sub messages, see Configuring Pub/Sub notifications.


You can receive notifications using Pub/Sub when any of the following clinical events occur:

Information about each event is added to the corresponding data store's Pub/Sub topic in the form of a message.

You can publish messages to any Pub/Sub topic in any project for which you have sufficient permissions. After the Pub/Sub topic receives the message, the message will be forwarded to any number of subscribers to the topic.

DICOM notifications

For information on using Pub/Sub notifications with DICOM data, see DICOM Pub/Sub notifications.

FHIR notifications

For information on using Pub/Sub notifications with FHIR data, see FHIR Pub/Sub notifications.

HL7v2 notifications

The following diagram shows the flow of notifications that occur when an HL7v2 message is ingested or created:


  1. The Cloud Healthcare API ingests an HL7v2 message from a care system.
  2. The message is stored in an HL7v2 store.
  3. The HL7v2 store creates and sends a Pub/Sub message to the store's Pub/Sub topics that have a filter that matches the HL7v2 message.
  4. Pub/Sub forwards the Pub/Sub message to the topics' subscriptions.
  5. The subscribers receive a notification, in the form of a Pub/Sub message, from their subscription. Each subscription can have one or more subscribers for increased parallelism.

Notification format

Notifications sent to a Pub/Sub topic consist of two parts:

  • Attributes: A set of key:value pairs describing the event. These values can be used to filter which events a client receives by filtering messages from a subscription.
  • Data: A string that contains an identifier for the relevant FHIR resource, DICOM instance, or HL7v2 message.

DICOM instance data

When a DICOM instance is stored in a DICOM store, the following identifier is always included in the data field of the Pub/Sub message:


Notifications for a stored DICOM instance do not contain any attribute values.

HL7v2 message data and attributes

When an HL7v2 message is created or ingested into an HL7v2 store, the following identifier is always included in the data field of the Pub/Sub message:


The following set of key:value pairs is always included in the Pub/Sub message's attributes field:

Attribute name Possible values Example Description
msgType Any HL7v2 message type. ADT The type of HL7v2 message that was created or ingested.

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