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Owning committee name

  • Infrastructure & Messaging

Committee Approval Date:

Sept 08 2017

Contributing or Reviewing Work Groups

FHIR Resource Development Project Insight ID


Scope of coverage

This represents the description of a type of message that can be sent from one system to another using the FHIR message paradigm. It describes the content of the message, the triggering event and the expected behavior of the receiving system. It can be thought of as the parallel to OperationDefinition, but for the messaging paradigm rather than the services paradigm. It is an infrastructure resource and can be used in all possible contexts.

RIM scope

N/A - This would have been handled at the RIM layer. It sort of acts like a v3 Interaction definition.

Resource appropriateness

Message Definitions have been a key part of HL7 since v2. It includes the definition of the triggering event, the structure of transmitted messages and what sorts of responses are permitted. This same set of information existed in the v3 methodology. In FHIR, this information is currently captured as part of CapabilityStatement. However, in doing so, it doesn't support the re-use of message definition information. There's definitely a need for message definitions to be created in implementation guides and then referenced in down-stream CapabilityStatements.

Each MessageDefinition is stand-alone and independently identifiable and maintainable, sharing the characteristics of other MetadataResources such as ValueSet and StructureDefinition. As such it can be queried, subscribed to, included in implementation guides, etc. in the same manner as any other infrastructure resource.

Expected implementations

This will be implemented by all implementation guides and specifications that need to define messages.

Content sources

v2 chapter 2, v3 MIF, FHIR CapabilityStatement resource

Example Scenarios

  • Defining an "Admit Patient" message, including the focal resource, other resources to be included in the bundle, the event code and allowed response messages
  • Defining a messaging equivalent of a FHIR operation (with the ability to do asynchronous and routed processing)

Resource Relationships

  • MessageDefinition will point to StructureDefinition (or potentially GraphDefinition) to define the content for the message.
  • MessageDefinition will point to other MessageDefinitions to define allowed responses to a given message
  • ConformanceStatement will point to MessageDefinition indicating the messages that are/should be supported by a system


For inclusion as draft in STU 3, publish as STU in release 4

gForge Users

lloyd_mckenzie ajulian

When Resource Proposal Is Complete

When you have completed your proposal, please send an email to