Engineering healthcare systems in C#/.NET using HL7 & FHIR and why domain knowledge is important

HL7 FHIR is the modern standard for healthcare data exchange, built on RESTful APIs using JSON/XML. The Firely SDK for .NET provides typed POCO classes for FHIR resources like Patient, Practitioner, and Observation. Key implementation details include using FhirJsonDeserializer (not the deprecated FhirJsonParser) for thread-safe parsing, handling Bundle collections, validating resources with the SDK's Validator, and using FhirClient for server communication. Healthcare systems require storing raw FHIR JSON alongside extracted data, implementing proper audit logging, encryption for PHI (Protected Health Information), and compliance with HIPAA/GDPR regulations. Domain knowledge in healthcare significantly accelerates development by providing understanding of clinical workflows and medical terminology.