Connect another system: HL7 v2 and the FHIR API

HL7 v2 ADT, results and pharmacy messages come in over HTTP, a folder or MLLP; orders go out. Other applications read the record through the FHIR R4 API with a client id and secret.

Inbound ADT A01/A03/A04/A08 admit, discharge, register and update patients; ORU R01 results become observations; RDE O11 becomes an outside medication list. Every message gets an ACK: AA accepted, AE could not be applied, AR rejected.

1. Create an HL7 interface (Interoperability > HL7 Interfaces) with the partner's application and facility names.
2. For MLLP, set the port, enable the interface, and start the server with HL7_MLLP=on. It is off by default.
3. For FHIR, register a client under FHIR Clients with the scopes it needs. Copy the secret: it is shown once.
4. The client asks POST /fhir/r4/auth/token for a token (client_credentials) and reads /fhir/r4/Patient, Observation and the rest.