ISO/HL7: FHIR Application Server

Minimalistic scalable microseconds precise FHIR application server in Elixir.

Features

• Extremely Compact Codebase (<10K LOC)
• Erlang Records Internal Representation (for type-checking and compact footprint)
• Fast (<5ms) JSON Schema draft-07 Mutual Dependency Validator
• FHIR Protocol Version 5.0.0 (204 resource types)
• FHIR Schema Support for R4/R5
• FHIR Terminology (50 code systems)
• HTTP Endpoints

Setup

$ mix deps.get
$ iex -S mix
ISO/HL7 27931:2009 application server listening at port: 9234.
JSON Schema: draft-07, FHIR Protocol Version: 5.0.0.
Interactive Elixir (1.12.2) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)>

Validation (μs):

> HL7.Validation.test
  ...
  ],
  [
    {:Person, 1071, "OK"},
    {:PlanDefinition, 4544, "OK"},
    {:PlanDefinition, 20023, "OK"},
    {:Practitioner, 721, "OK"},
    {:PractitionerRole, 2167, "OK"},
    {:Procedure, 1065, "OK"},
    {:ProcedureRequest, 2598, "OK"},
    {:Provenance, 2510, "OK"},
    {:Quantity, 351, "OK"},
    {:Questionnaire, 3633, "OK"},
    {:QuestionnaireResponse, 1215, "OK"},
    {:Reference, 749, "OK"},
    {:Schedule, 876, "OK"},
    {:SearchParameter, 4247, "OK"},
    {:Sequence, 3199, "OK"},
    {:Slot, 879, "OK"},
    {:Specimen, 1166, "OK"},
    {:Subscription, 554, "OK"},
    {:Substance, 690, "OK"},
    {:SupplyDelivery, 1278, "OK"},
    {:SupplyRequest, 9064, "OK"},
    {:Task, 50683, "OK"},
    {:TerminologyCapabilities, 3249, "OK"},
    {:TriggerDefinition, 1955, "OK"},
    {:ValueSet, 1616, "OK"},
    {:VisionPrescription, 2435, "OK"}
  ]
]

Note that List instance is 64K JSON object. Note that best possible (fastest) validation at a given platform can only be achieved with a validation code compiler.

HL7/FHIR HTTP API

Meta

$ curl -X GET "http://localhost:9234/\$meta"
[
  {
    "parameters": [
      {
        "name": "return",
        "valueMeta": {
          "profile": [
            "https://hl7.erp.uno/priv/schema/Person.schema.json",
            "https://hl7.erp.uno/priv/schema/Patient.schema.json",
            "https://hl7.erp.uno/priv/schema/Organization.schema.json",
            "https://hl7.erp.uno/priv/schema/Location.schema.json"
          ],
          "security": [
            {
              "code": "N",
              "display": "normal",
              "system": "https://hl7.erp.uno/CodeSystem/v4"
            }
          ],
          "tag": [
            {
              "code": "N",
              "display": "normal",
              "system": "https://hl7.erp.uno/tag/"
            }
          ]
        }
      }
    ],
    "resourceType": "Parameters"
  }
]

Validation

$ time curl -X POST "http://localhost:9234/List/\$validate" -d @samples/List/List.json
{
  "base": "",
  "id": "01111313-long",
  "spec": "$validate",
  "type": "List",
  "verify": {
    "code": "success",
    "message": "Object conforms to List of R5 schema."
  }
}
real    0m0.011s
user    0m0.005s
sys     0m0.000s

HL7/FHIR R5 Protocol Modules

• General
• Foundation
• Security
• Terminology
• Administration
• Clinical
• Diagnostic
• Medications
• Financial
• Workflow

Primitive

Internal data types: instant, time, date, dateTime, base64binary, decimal, integer64, boolean, url, code, string, integer, uri, canonical, markdown, id, oid, uuid, unsignedInt, positiveInt.

General

General-purpose types: Address, Age, Annotation, Attachment, ContactPoint, Count, Distance, Dosage, Duration, Element, HumanName, Identifier, Meta, Money, Period, Quantity, Ratio, Range, RatioRange, Reference, SampledData, Timing.

Foundation

Infrastructural types: Resource, DomainResource, Basic, Bundle, Composition, List, Subscription, Endpoint, ServiceDefinition.

Security

Security-sensitive types: Consent, Permission, Provenance, Signature.

Terminology

Dictionary-related types: CodeSystem, ValueSet, ConceptMap, NamingSystem, Coding, CodeableConcept, CodeableReference, Coding.

Administration

Administrative types: Patient, RelatedPerson, Person, Group, Practitioner, PractitionerRole, Organization, Account, Location, HealthcareService, Endpoint, Schedule, Slot, SpecimenDefinition, EpisodOfCare, Encounter, EncounterHistory, Appointment, Flag, ObservationDefinition, NutritionProduct, Device, DeviceDefinition, DeviceMetric, DeviceUsage, DeviceAssociation.

Clinical

Clinical data types: Condition, Procedure, CarePlan, Goal, DetectedIssue.

Diagnostic

Diagnostic data types: Observation, Specimen, BodyStructure.

Medications

Medications types: Medication, MedicationDispense, MedicationRequest, MedicationStatement, MedicationAdministration, Immunization, ImmunizationEvaluation, ImmunizationRecommendation.

Financial

Financial data types: Account, Contract, Claim, Enrollment, Coverage, PaymentNotice.

Workflow

Workflow modeling data types: ActivityDefinition, Definition, EventDefinition, MessageDefinition, PlanDefinition, ObservationDefinition, ClinicalUse, Measure, OperationDefinition, Requirements.

Development Environment

IEx.configure(width: :erlang.element(2, :io.columns))
IEx.configure(inspect: [limit: :infinity])

Code Size

Low-code schema design suitable for other language implementations. Yes, it is correct, I manually commited and verified 1K files in 1 month.

Language	Package	Files	LOC	Description
Elixir	Xema	17	4536	JSON Validation
Elixir	FHIR	30	682	FHIR HTTP
JSON	FHIR	1044	143809	FHIR Schema + R5 Samples suite

Publications

• 2024-02-18 ISO/HL7 FHIR: Валідація

Credits

• Namdak Tonpa