Introduction to FHIR Messaging

To use this eReferral specification, it is important to first understand the basics about the FHIR messaging paradigm. The messaging paradigm centers around the concept of “events” (MessageHeader.eventCoding.code), such as sending a new referral or updating a referral. These events can trigger sending a “Message” between systems. The message sender assembles each message into a bundle with all of the relevant resources according to the nature of the specific message event. The recipient system knows how to process the message based on the event indicated in the message.

Each message consists of 4 parts:

  1. The Bundle resource: of "type" : "message” is used to provide meta information about the resources in the message.
  2. The MessageHeader resource: is always the first resource in the bundle. The event (MessageHeader.eventCoding.code) defines the nature of the message, and instructs the receiving system what workflow to initiate.
  3. The Main Resource: that the message is about is always included immediately after the MessageHeader. For example, if the message is about sending a new ServiceRequest, then the ServiceRequest will be present after the MessageHeader. If the message is about an updated Appointment, then the Appointment resource will be present after the MessageHeader, etc...
  4. Other Resources Related to the Message are included in the bundle. For example, when submitting a new ServiceRequest, other resources such as Patient and Location will be included to prevent the need for multiple API calls to support one API request.

Learn more about the FHIR messaging paradigm on the HL7 FHIR page.

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