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The configuration model

Declarative surfaces configured with standard FHIR resources versus code extensions.

Four declarative configuration surfaces​

Application behavior in OHS Player is driven by four standard configuration surfaces defined using HL7 FHIR specifications.

SurfacePurposeStandard FHIR artifact
Data captureForm fields, question groups, and validation rulesQuestionnaire with Structured Data Capture
Resource extractionTransforming questionnaire responses into clinical resourcesExtraction definitions on Questionnaire
Screen viewsProjecting FHIR data into lists and profile screensViewDefinition, ViewJoinMap, and ViewConfig
Clinical workflowDefining care plans, scheduled tasks, and activitiesPlanDefinition and ActivityDefinition

All configuration artifacts are packaged together in the Configuration IG.

Data capture and validation​

Forms are standard FHIR Questionnaire resources using Structured Data Capture. Form fields, input types, groupings, and validation constraints are defined in JSON or XML without custom UI code.

  • Initial expressions pre-populate answers from patient records.
  • Calculated expressions compute clinical scores in real time.
  • Answer expressions supply dynamic option lists using FHIRPath.
  • Validation rules enforce required fields, value ranges, and regex constraints on device.

Resource extraction​

Completed forms produce a QuestionnaireResponse resource. Extraction translates those responses into structured FHIR records such as Patient, Observation, and Condition using template-based extraction and FHIRPath mappings.

Screen views​

Screens are assembled from declarative view definitions and reusable Jetpack Compose renderers.

  • ViewDefinition projects FHIR resource fields into flat view states using SQL-on-FHIR specifications.
  • ViewJoinMap combines multiple related resources such as a patient with active conditions into unified rows.
  • ViewConfig supplies configurable parameters and display options to renderers.
  • Renderers draw the resulting view states on screen.

Where the boundary with code falls​

  • Declarative configuration is used when adapting existing screens, adding new questionnaires, modifying indicators, or creating new patient registers.
  • Code extension is used when creating entirely new UI widget renderers or developing custom gateway endpoints.

Where to go next​