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ReFHIR ReFHIR ReFHIR

Introduction

FHIR (say “fire”) is the standard format and web API that healthcare software uses to store and share patient data: patients, medications, lab results and more. A FHIR server is a program that holds that data and answers questions about it.

ReFHIR is an open-source FHIR server, written in Rust, from the nonprofit HAIHQ. It has one difference. FHIR’s standard API answers a question once, and the answer is out of date as soon as the data changes. ReFHIR keeps the question open and sends the new answer whenever a change affects it, so a screen or an AI agent always works from what is true now, with no polling or refresh code of its own.

What that looks like

Section titled “What that looks like”

A client runs a FHIR query and stays subscribed to its result. When a committed write changes what the query returns, the server re-runs it and pushes the new result.

GET /Observation?patient=Patient/123&status=final   <- an ordinary FHIR query: one answer
ws://host/sync   subscribe: Observation?patient=Patient/123&status=final
                 <- the matches now, then a new result whenever a commit changes them

The idea behind it is one sentence: queries, not events, are the primary unit of synchronization. An event says that something changed. A live query says what the answer is now, which is what a screen or an agent needs. How live queries work shows what the server does, and Live queries for AI agents covers why it matters for agents that act on state that may have changed while they were thinking.

How it differs from a typical FHIR server

Section titled “How it differs from a typical FHIR server”

FHIR’s standard API is request and response. After the answer arrives, staying current is left to your code: polling, notifications, caches and refresh logic, written again in every product. ReFHIR moves that work into the server.

  • The data changes. A typical server leaves you to ask again, or to wire up notifications, which say that something changed and not what the list looks like now. ReFHIR re-runs your question and sends the new list.
  • A medication is stopped. It leaves the list, and the new list simply does not contain it.
  • An AI agent is working. It can check that what it read is still true before it acts.
  • Software that already speaks FHIR can use it, because ReFHIR is also a standard FHIR server: REST, search, transactions and SMART on FHIR authorization.

See Live queries and FHIR Subscriptions for how it differs from the notification feature FHIR already has.

Who it is for

Section titled “Who it is for”
  • People building screens that must stay current, such as worklists and dashboards. Start with the tutorial.
  • People building AI agents over patient data, who want working context that stays current and a way to notice that it changed. Read Live queries for AI agents.
  • People who want a FHIR server they can run themselves: open source under Apache-2.0, as a Docker image, a Helm chart or a binary. See Install.

Versions

Section titled “Versions”

ReFHIR is at version 0.x, so settings and the /sync protocol can change between releases. The changelog says what changed. Upgrades are forward-only, so back up your database before you upgrade.

Next

Section titled “Next”