Initiate a FHIR Bulk Data $import operation to asynchronously ingest NDJSON resources into a FHIR server

Steps

1. Confirm the target FHIR server supports $import by checking the CapabilityStatement for the operation definition or server documentation; $import is defined in the FHIR Bulk Data Access IG as an asymmetric counterpart to $export
2. POST /$import with a Parameters resource containing: inputFormat (application/fhir+ndjson), inputSource (base URL of the source), storageDetail (type and credentials if applicable), and input parameters listing resource type and URL for each NDJSON file
3. Include Prefer: respond-async in the request header; receive a 202 Accepted response with a Content-Location header pointing to the import status endpoint
4. Poll Content-Location with GET until the response is 200 OK; parse the completed response body for outcome details including counts of resources created, updated, or failed
5. Review any error file URLs in the response to retrieve NDJSON-formatted OperationOutcome resources describing individual resource import failures
6. Verify a sample of imported resources by querying them directly on the FHIR server using their expected IDs or search parameters