parse HL7v2 ADT messages and map fields to FHIR R4 resources

Steps

1. Use a well-tested HL7v2 parsing library for your language (e.g. hl7apy for Python, HAPI for Java, or nHapi for .NET) to deserialize the pipe-delimited message into a structured object model.
2. Extract the MSH segment to determine message type (e.g. ADT^A01 for admit, ADT^A08 for update) and use this to decide which FHIR operation to perform (create vs. update).
3. Map PID segment fields to a FHIR Patient resource: PID-3 to identifier, PID-5 to name, PID-7 to birthDate, PID-8 to gender, PID-11 to address.
4. Map PV1 segment fields to a FHIR Encounter resource: PV1-2 to Encounter.status, PV1-3 to Encounter.location, PV1-44/45 to Encounter.period.
5. Use a FHIR transaction Bundle to POST both the Patient and Encounter in a single atomic request, referencing the Patient via a conditional URL or fullUrl.
6. Validate the resulting FHIR resources against US Core or relevant profiles using a FHIR validator before persisting.