New Zealand Health Terminology Service (NZHTS) Implementation Guide - Local Development build (v0.9.0) built by the FHIR (HL7® FHIR® Standard) Build Tools. See the Directory of published versions

Nzhts Usage

NZHTS integration pattern usage

NZHTS is the national service for mastering, authoring and distributing authoritative health terminology. It is the source from which terminology is discovered and obtained; it is not intended to be a shared runtime terminology backend for New Zealand's clinical applications.

Appropriate uses of NZHTS

NZHTS is currently intended to be used for:

• authoring and maintaining nationally managed terminology artifacts;
• discovering CodeSystems, ValueSets, ConceptMaps, NamingSystems etc. and updates to these terminology artifacts;
• sourcing authoritative reference material for implementation, testing or distribution;
• design-time terminology operations, including validating and expanding terminology during a FHIR IG publication workflow; and
• obtaining versioned terminology content through the NZHTS syndication feed for loading into downstream terminology services.

These are human-in-the-loop, authoring, build-time or content-distribution activities. They are normally tolerant of network access, authentication and the operational characteristics of a shared national service.

Do not make NZHTS a clinical runtime dependency

Clinical applications should not call NZHTS synchronously for routine user-facing or clinical workflows such as type-ahead search, code lookup, code validation or ValueSet expansion. NZHTS is not designed to meet an application's runtime latency, throughput, availability or support requirements. A direct dependency would also expose clinical workflows to internet connectivity, authentication and national-service maintenance events.

Direct access by the IG Publisher and other design-time tools is appropriate; direct access on every clinical transaction is not.

Production application pattern

The expected production pattern is:

NZHTS national master -> syndication feed -> integrator-managed terminology service -> clinical applications

An integrator should use the syndication feed to discover and retrieve the required versioned releases, test them, and promote them into its own environment on a controlled schedule. The downstream service may be a high-performance in-memory terminology service for a small, well-defined set of operations, or a separate local FHIR terminology server where richer functions such as $expand, $validate-code, $lookup, subsumption, version history or locally managed terminology are required.