HL7 v2 vs FHIR: selecting an integration approach
Understand the trade-offs between event messages and modern healthcare resource APIs.
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HL7 v2 and FHIR address overlapping interoperability needs but use different technical models. Many healthcare environments use both.
HL7 v2: event-driven messages
HL7 v2 messages are commonly used for operational event flows such as admissions, discharges, orders and results. Messages are often delivered through existing interface engines and established transport patterns such as MLLP.
FHIR: resource-based exchange
FHIR defines resources and interactions commonly used through RESTful APIs. This can support web and mobile products and modern interoperability architectures, subject to the profiles, permissions and workflows in the relevant ecosystem.
How to decide
- If you must connect to an incumbent clinical system, start with the interfaces it actually supports.
- For API-centric applications, investigate FHIR implementation guides and supported server capabilities.
- For live operational events, confirm whether push messaging, subscriptions or another event pattern is required.
- For systems spanning old and new environments, consider an integration layer translating between HL7 v2 and FHIR with explicit data-mapping rules.
Project scoping questions
Ask which side owns the integration contract, how failures are acknowledged, whether write operations are allowed, what patient identity rules apply and how conformance will be tested.
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