External FHIR servers as a data backend

This article outlines how to use Aidbox Forms with external FHIR servers.

Overview

Aidbox Forms module uses Aidbox's FHIR API capabilities to store all it's data. But sometimes it's appropriate to use other FHIR backends. Aidbox Forms provides a simple and granular way to specify external FHIR servers for data management.

Data Domains

Data used by Aidbox Forms has different nature and can have different storage requirements and strategies.

We split data in 4 domains, and last 3 of them can have it's own FHIR backend:

Because system resources are non FHIR resources - there is no FHIR backend configuration for them.

1. System resources - non-FHIR resources, used by Aidbox Forms for extended functionality.

2. Content resources - Questionnaire resource (the main focus and result of Forms Builder).

3. Terminology resources - ValueSets and Concepts.

4. Production resources - QuestionnaireResponse resource and other FHIR resources that contain PHI/Production data.

Storage Defaults

By default all data is stored in Aidbox and there is no need for any configuration.

Storage Configuration

Storage configuration lives in default SDCConfig resource. (read more)

IMPORTANT: config should have default: true property set

Storage Configuration structure

For every domain we have separate key:

• form-store - content resources domain

• data-store - production resources domain

• term-server - terminology resources domain

To enable external FHIR Backend we should specify next fields for it:

• endpoint - URI to FHIR API

• headers (optional) - Additional HTTP headers for requests (Authorization for example)

Example:

[store-key]:
    endpoint: 'http://my-ehr.com/fhir'
    headers:
        Authorization: 'Basic cm9vdDpzZWNyZXQ='

Form Storage

Store Questionnaire resource only

WARN: assembled forms and components are not yet supported with external storage.

form-store:
    endpoint: "https://fhir-server.com/fhir"

Data Storage

Store QuestionnaireResponse and all FHIR Resources except Questionnaire.

This store will be used as source in $populate operations, and as target in $extract+$process-response operations

data-store:
    endpoint: "https://fhir-server.com/fhir"

Terminology service

ValueSet search and ValueSet/$expand operation

term-service:
    endpoint: "https://fhir-server.com/fhir"

Full config example:

POST /SDCConfig
content-type: text/yaml

id: cfg-1
resourceType: SDCConfig
name: Config with external fhir servers
default: true
form-store: 
    endpoint: 'http://forms-repo.com'
data-store: 
    endpoint: 'http://my-ehr.com/fhir'
    headers:
        Authorization: 'Basic cm9vdDpzZWNyZXQ='
term-server:
    endpoint: 'http://tx.com/fhir'

Multitenancy Support

• Default system SDCCOnfig (for root Organization) does not take effect on tenants

• Every tenant have their own default config and thus separate FHIR backends setup