Bundle referencing

Resources in Bundles SHOULD NOT use contained resources.

References to other resources in the Bundle SHOULD use the fullUrl uuid, e.g.

"reference": "urn:uuid:66c519dd-423f-4238-89c8-91c5be52f330"

References to other resources not included in the Bundle SHOULD use the path for the resource, including the uuid, if this can be found on the GMS central broker (the central broker will replace a urn:uuid with its own ID on create, these will be returned to clients in responses) e.g.

"reference": "Specimen/840d075e-0480-4134-ae51-27f572731cc8"

If the resource is hosted on another NHS service, for example patient records on PDS, these should be referenced by identifier using the appropriate system for the identifier, e.g.

"reference": {
  "identifier": {
    "system": "https://fhir.nhs.uk/Id/nhs-number",
    "value": "9999999999"
  }
}

If a resource is contained on another system, outside NHS central services, this SHOULD be referenced with an absolute url. The URL SHALL be resolvable (though these links will not be validated/followed by the central broker) and preferably return a FHIR resource of the appropriate type e.g.

"reference": "https://www.christie.nhs.uk/ehr/LabOrder123456"

Specific instances where each of the above reference types are allowed are defined within the Profiles pages. NOTE: The central broker will not be supporting references by identifier where the resource exists on the server. In this case, the client SHOULD retrieve the resource via a search on identifier to obtain the logical ID for any resource level interactions.

All profiles within transaction bundles should reference each other i.e. none should be orphaned.

Any additional resources not linked from another resource in a transaction bundle SHALL be excluded, or sent in a separate transaction. The expected list of resources and cardinalities in a typical test order or report transaction are detailed in GraphDefinitions.

It is expected the central broker will check and maintain referential integrity, where these references point to resources stored on the central broker. If a request fails this check, the transaction will fail with the appropriate HTTP error code, e.g. 422. The response will be a 'transaction-response' bundle, including an OperationOutcome FHIR resource for each resource submitted in the transaction Bundle with diagnostics for each. Resources passing validation will return 200 but will not result in resources being created on the server if the transaction contains an error (the transaction will be rejected as a whole).

Conditional Creates/Updates

While not supported for the alpha, it is expected the central broker will support conditional create or update operations (as defined in transaction request objects). This will allow clients to only create resources, such as Patient/PractitionerRole, where no resource containing their identifier already exists. Responses where conditional criteria are not satisfied are still under discussion as of the time of publication.

Resource Reference (Duo/Trio Tests)

When the test type is Duo or Trio there will usually be specimens from more than one patient. Due to the way references work within FHIR, the Task resource will reference the Specimen resources for all participants within the “input” element, and each specimen will reference the patient it relates to using the “subject” element.