CQF API (/cqf)

Mercury implements the FHIR CQF operation surface under the /cqf base path, so it slots into a measure-calculation pipeline in place of the reference evaluator. This page covers the endpoints you’ll use most.

Note

Base URL below is http://127.0.0.1:8080. In the drop-in container stack, Mercury is on port 8090. Adjust to your deployment.

Capability statement

curl http://127.0.0.1:8080/cqf/metadata

Returns the FHIR CapabilityStatement describing the supported resources and operations.

Data

Load a FHIR bundle into the server’s patient corpus, so evaluations can reference subjects by id.

POST /cqf/data/bundle
Content-Type: application/fhir+json

curl -X POST http://127.0.0.1:8080/cqf/data/bundle \
  -H "Content-Type: application/fhir+json" \
  --data @patients.bundle.json

See Loading data: preload vs inline for when to preload vs. supply data inline.

Library

Create, read, update, and delete FHIR Library resources. Mercury accepts CQL directly and also ELM XML as an alternative input.

# Create (returns 201)
curl -X POST http://127.0.0.1:8080/cqf/Library \
  -H "Content-Type: application/fhir+json" \
  --data @Test.Library.json

# Read
curl http://127.0.0.1:8080/cqf/Library/Test

Tip

Canonicals resolve as Library/{id}|{version}. If $evaluate returns 404, POST the Library first.

Measure

Measure resources support the same CRUD operations as Library.

curl -X POST http://127.0.0.1:8080/cqf/Measure \
  -H "Content-Type: application/fhir+json" \
  --data @Test.Measure.json

$evaluate

Evaluate a library expression (or a whole measure) for a subject. Returns 200 with a FHIR Parameters resource.

GET /cqf/Library/{id}/$evaluate?subject=Patient/{id}&expression={name}

curl "http://127.0.0.1:8080/cqf/Library/Test/\$evaluate?subject=Patient/123&expression=InDenominator"

Result — a Parameters resource whose evaluate part lists each expression and its value, e.g. InDenominator → "true".

Harness-compatibility stubs

For compatibility with existing tooling, Mercury exposes $data-requirements and $package as stubs. They respond so harnesses that call them don’t break; they aren’t full implementations.

GET /cqf/Library/{id}/$data-requirements
POST /cqf/Library/{id}/$package

Next steps

• REST surface (/api, /fhir) — health, translate, query, OpenAPI.
• CLI reference — drive these operations from the command line.
• Troubleshooting & FAQ — common $evaluate errors.