FHIR Resources are the data packages used to send or receive data from a FHIR repository. With STU-3, Standard for Trial Use, release 3 of FHIR, there are currently 92 resources defined. The HL7 organization wants enough resources to handle 80% of the healthcare workflows, but does not want so many that the standard would become too complex.
Resources are meant to capture a meaningful amount of data. For example, the following table provides examples of what would be, and would not be, a FHIR resource. Things like patient demographic data or allergies provide the perfect amount of data. For those familiar with HL7 V2 messaging, a resource would typically contain about the same amount of data as a segment in a HL7 V2 message.
The data housed within resources is broken out into four parts, in the following order:
Metadata – Contains details about the resource, such as when it was last updated.
Narrative – Contains XHTML so that the resource can be read in browsers without having to parse apart all the data
Extensions – Used to include data that is not part of the defined structure of the resource
Elements – Contains the structured data of the resource