Cerner/Oracle Health's FHIR API and SMART on FHIR Workflow Explained

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This article provides a technical deep dive by API Evangelist into the FHIR R4 API of the Cerner Millennium platform (now Oracle Health). The author emphasizes that because this EHR handles a large portion of national clinical data, its API must be viewed as a sequence of interconnected workflows rather than merely a list of resources. Three specific workflows are detailed: 1) The SMART on FHIR patient retrieval flow, which starts by fetching the CapabilityStatement to identify supported resources and endpoints, followed by locating the patient and pulling conditions, encounters, and procedures. 2) A conformance discovery flow that reads server metadata to enumerate available operations and structures—a crucial step for integrators. 3) A clinical resource write-back flow, demonstrating how generic create/update operations are used to document data back into the EHR after locating the patient. The author highlights that these workflows reference real `operationId`s from Oracle Health's OpenAPI specification, making them portable artifacts (Arazzo files). By presenting standardized patterns in this comparative format, the article argues that governance and procurement discussions within healthcare become more tractable across different vendors (e.g., Cerner vs. Canvas). This serves as a technical guide demonstrating how to standardize complex interoperability patterns.