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Policy

General

FHIR-GEN-01 HL7 FHIR standard compliance.

• All FHIR implementations MUST comply with the HL7 FHIR standard.
• All implementations of FHIR interfaces MUST comply with the requirements outlined in the relevant release of the HL7 FHIR standards, as outlined on fhir.hl7.org.

FHIR-GEN-02 Availability of FHIR resources on a public server.

• All FHIR resources are published on a public FHIR reference server.
• All FHIR resources relating to national systems and other nationally defined FHIR API profiles (including StructureDefinitions, ValueSets, OperationDefinitions, ImplementationGuides, etc.) that are ready for external use (in either DRAFT or ACTIVE status) MUST also be made available the HL7 Estonia reference server api.fhir.ee.
• Resources that are part of the National Estonian Health System (TIS) MUST also be published on a TEHIK branded public FHIR server fhir.tehik.ee.

FHIR-GEN-03 Avoid FHIR Document Paradigm

• Avoid FHIR Document Paradigm when possible. Use REST and Messaging Paradigms instead.

Conformance

FHIR-CONF-01 Support conformance

• All servers offering a FHIR API MUST publish a FHIR conformance/capability statement (in the form of a CapabilityStatement resource) at the root URL of their FHIR Server. Following HL7 EEBase-CapabilityStatement profile.

Profiling

FHIR-PROFILE-01 Profile tree

The FHIR standard provides a mechanism to specialise and extend FHIR resources by creating profiles. In Estonia, profiles are developed according to the following “levels”:

• Level 1: The base FHIR resource profiles defined by HL7 International.
• Level 2: The ‘Estonian Base Profiles’ are Estonia-wide profiles curated through the HL7 FHIR Estonia community and published on the HL7 Estonia FHIR reference server.
• Level 3: The implementation-specific profiles for a particular system or domain.
  Profiles for upTIS are published on the TEHIK FHIR Reference Server.
  Profiles for Tervisekassa projects are published on the HL7 Estonia FHIR Reference Server.

FHIR-PROFILE-02 Summary field

• Profiles MUST NOT define alternate summary fields for resources.- All FHIR base resources have several fields defined as ‘summary’ fields, which appear when the client requests summary versions of the resource to be returned (for example, in search results). These summary fields can only be defined in base resources and cannot be changed in any profiles.

FHIR-PROFILE-03 Must Support

• If mustSupport is true, conformant resource authors SHALL be capable of providing a value for the element and resource consumers SHALL be capable of extracting and doing something useful with the data element. If false, the element may be ignored and not supported.
• The mustSupport is used in the profiles where standard developers want to leave an element as “optional”, but want to state that implementers playing in a particular space must support that element.

Versioning

FHIR-VER-01: Versioning of Profiles and Resources

• Nationally defined FHIR profiles will be versioned during development using Git, following the standard GitFlow model. The versioning for published artefacts will broadly follow semantic versioning standards. The major and minor versions will be visible, and the patch version MAY also be exposed. Version numbers held in profiles and resource instanced MUST therefore be in one of the following forms: MAJOR – e.g. 1 MAJOR.MINOR – e.g. 1.0 MAJOR.MINOR.PATCH – e.g. 1.0.2
• The version number MUST NOT be included in the profile name.
• The version number MUST be used as the profile version attribute.

Example of a version number in Estonian base Organization

{
  "resourceType": "StructureDefinition",
  "id": "EEBaseOrganization",
  "url": "https://fhir.ee/StructureDefinition/ee-organization",
  "version": "1.0.0"
}

Naming

To promote consistency and make it easier for implementers to locate suitable profiles, extensions, value sets and others for their projects, a naming strategy will be adopted for EEBase-defined FHIR assets or FHIR assets derived from the EEBase. All EEBase-derived implementation guides and FHIR assets MUST follow these rules to claim conformace with the EEBase. For detailed definitions of concepts discussed within this guidance document, refer to the appropriate published version of the FHIR standard.

FHIR-NAME-01: Convention for Profile definition

FHIR Profile name MUST follow an agreed format. The FHIR profile name consists of several logical name segments:

• Base URL: The URL used for standard publishing. For example, hl7.org for HL7 International and fhir.ee for HL7 Estonia. Mandatory.
  • Check the full list of providers.
  • You can register your project with fhir.ee namespace through HL7 Estonia Board.
• Base: The provider name. May differ for resource name and for id. Mandatory.
  • The base for Estonian Base is EEBase for resource names and ee for id-s.
• ResourceType: The name of the FHIR Resource Type or the category of FHIR Resource. Mandatory.
• BusinessNames: Business names are only used where mutiple profiles exist for a given base resource type. Optional.
• No business version information is allowed in the resource URL.
• Name segments SHOULD be U.S. English (spelled correctly)

The FHIR profile consists of (computable) name, id and url:

• Resource Name: The [Base], [ResourceType] and [BusinessNames] without hyphen (-) SHOULD be used as resource name. Segment names in FHIR Profile resource name MUST follow Pascal case convention. Resource name also known as computable name that MAY be used for code generation.
• Resource Id: The [Base]-[ResourceType]-[BusinessNames] with hyphen (-) and in lower-case is RECOMMENDED for this purpose.
• Resource Url: URL reuse the resource id - [Base URL]/StructureDefinition/[Resource Id].
• Title: The title of the resource MUST be the [Base], [ResourceType] and [BusinessNames] with added spaces to make it human readable and understandable.

Examples:

FHIR-NAME-02: Convention for Extension definition

FHIR Extension MUST follow an agreed format.

The name of FHIR extension follows the rules of the FHIR profile. The only difference FHIR Extension should have word “Extension” at the beging of Resource Name.

Examples:

FHIR-NAME-03: Convention for OperationDefinition resource definition

FHIR OperationDefinition MUST follow an agreed format.

The FHIR operation name consists of several logical name segments:

• Base URL: The URL used for standard publishing. See profile definition.
• Base: The provider name. See profile definition.
• BusinessNames: The business name of OperationDefinition. Mandatory.
• No business version information is allowed in the resource URL.

The FHIR operation consists of (computable) name, id and url:

• Resource Name: The [Base] and [BusinessNames] without hyphen (-) SHOULD be used as resource name. Segment names in FHIR operation name MUST follow Pascal case convention. Operation name also known as computable name that MAY be used for code generation.
• Resource Id: The [Base]-[BusinessNames] with hyphen (-) and in lower-case is RECOMMENDED for this purpose.
• Resource Url: URL reuse the resource id - [Base URL]/OperationDefinition/[Resource Id].
• Title: The title of the resource MUST be the [Base] and [BusinessNames] with added spaces to make it human readable and understandable.

Examples:

FHIR-NAME-04: External CodeSystem and ValueSet names

• The FHIR-managed CodeSystems SHOULD use names defined by FHIR working groups.
• The FHIR-managed ValueSets SHOULD* use names defined by FHIR working groups.
• Some ValueSets that use SNOMED CT will refer directly to SNOMED CT artefacts, for example, SNOMED CT Ref Sets, and there will not be a need to create a CodeSystem resource. There may be other ValueSets which follow the same principles, for example, LOINC.

FHIR-NAME-05: CodeSystem name convention

FHIR CodeSystems MUST follow an agreed format.

The code systems name segments are defined as follows:

• Base URL: The URL used for standard publishing. See profile definition.
• Base: The standard provider name. See profile definition. Conditional.
• BusinessNames: The business names of the CodeSystem. The CodeSystem name MUST have at least one BusinessName segment. Where a CodeSystem MAY is used across several domains, business names SHOULD reflect that. Mandatory.
• Name segments SHOULD be U.S. English (spelled correctly)

The CodeSystem consists of (computable) name, id and url:

• Resource Name: [Base] and [BusinessNames] without hyphen (-) SHOULD be used as the resource name. Segment names in FHIR CodeSystem MUST follow Pascal case convention.
• Resource Id: [Base] and [BusinessNames] in lowercase where every word is separated with a hyphen (-).
• Resource Url: URL reuse the resource id - [Base URL]/CodeSystem/[Resource Id].
• Resource Title: The resource’s title MUST be [Base] and [BusinessNames] with added spaces to make it human-readable and understandable.

Example:

FHIR-NAME-06: ValueSet name convention

FHIR ValueSet MUST follow an agreed format.

See CodeSystem convention. The only difference is resource url:

• Resource Url: URL reuse the resource id - [Base URL]/ValueSet/[$ResourceId].

Examples:

FHIR-NAME-07: NamingSystem name convention

FHIR NamingSystem MUST follow an agreed format.

The code systems name segments are defined as follows:

• Base URL: The URL used for standard publishing. See profile definition.
• Base: The standard provider name. See profile definition. Optional.
• BusinessNames: The business names of the identifier system.
• Name segments SHOULD be U.S. English (spelled correctly).

The NamingSystem consists of (computable) name, id and url:

• Resource Name: [Base] and [BusinessNames] without hyphen (-) SHOULD be used as the resource name.
• Resource Id: [Base] and [BusinessNames] in lowercase where every word is separated with a hyphen (-).
• Resource Url: URL reuse the resource id - [Base URL]/NamingSystem/[Resource Id].
• Resource Title: The human-readable and understandable resource’s title.

Examples:

Resource identifiers

FHIR-ID-01 FHIR resource ID

• Resource IDs MUST be generated only by FHIR server.
• Business ID-s MUST NOT be used as the resource ID.

FHIR-ID-02 References between REST resources

• References between ReST resources SHOULD be literal references without FHIR server path but MAY be logical references.
  • When using the FHIR ReST Paradigm, resources SHOULD reference other resources via URL (i.e. a literal reference in the FHIR standard). The resource owner should (where possible) only reference other resources that they can be relatively confident consumers of their API will be able to resolve and retrieve. For referencing other things outside this, a logical reference SHOULD be used.
  • Note: URL references to other resources will (by default) return the latest version of the referenced resource. If this isn’t desirable, the resource owner may either contain the resource or use a versioned URL as a literal reference.

FHIR-ID-03 Logical references

• References in FHIR messaging SHOULD be logical references.
• ​When using the FHIR Messaging Paradigm, messages will likely include references to external resources. These references SHOULD use an identifier from a known NamingSystem. This is known as a logical reference in the FHIR standard. The NamingSystem URI SHOULD be searchable on a FHIR Reference server to return the NamingSystem resource that describes the identifiers used (for example, https://fhir.ee/NamingSystem).

Publishing

FHIR-PUB-01 Official repository

• The Github repository for Estonian FHIR Base is https://github.com/HL7EE/ig-ee-base.

FHIR-PUB-02 Availability of source code

• All FHIR resources relating to national systems and other nationally defined FHIR API profiles (including StructureDefinitions, ValueSets, OperationDefinitions, ImplementationGuides and others) MUST be held on a publicly available GitHub repository which MAY be synchronised with a Simplifier project.

FHIR-PUB-03 Development of standard

• Comments, feedback and suggestions from developers on FHIR resources (and associated documentation) SHOULD be managed through Github using the standard features for raising and tracking issues on the appropriate project.
  • Use https://github.com/HL7EE/ig-ee-base/issues for HL7EE EEBase issue mananagement.

FHIR-PUB-04 Pattern for URI-s

• All FHIR resource URIs must be resolvable URLs.
  • The new URI-s SHOULD be registred in GitHub fhir.ee project
• All FHIR resources relating to national systems and other nationally defined FHIR API profiles (including StructureDefinitions, ValueSets, OperationDefinitions, ImplementationGuides and others) MUST have a URI that is a resolvable URL. Usually, this will be the URL of the resource on the FHIR API reference server (fhir.ee).

FHIR-PUB-05 Packaging

• All FHIR resources MUST be made publicly available as FHIR Implementation Guide and released as a FHIR package.
• ​All FHIR packages that may be used as dependecy for other packages SHOULD uploaded to Estonian FHIR Packages Repository through GitHub fhir.ee project.

Serialization

FHIR-SER-01 Supported mime-types

• FHIR REST APIs MUST support JSON serialisation and SHOULD also support XML serialisation.
  • All FHIR ReST endpoints MUST support JSON formatted requests/responses.
  • FHIR ReST endpoints SHOULD also support XML formatted requests/responses.
  • The serialisation mime-types supported MUST be declared in the Conformance/CapabilityStatement resource for the endpoint, and the server MUST use the usual FHIR mechanisms to allow clients to request a specific Content Type as per the FHIR spec (servers may choose to reject the use of XML if it is not supported).

FHIR-SER-02 Allowed namespaces

• Namespaces outside those defined in the FHIR specification MUST NOT be used.
  • The FHIR standard specifies a specific namespace for FHIR XML elements, with a second namespace for XHTML content in narrative sections. Those specifying FHIR APIs MUST not use other namespaces in their APIs.

FHIR operations

FHIR-OPER-01 Reuse standard FHIR operation

• Where a request maps to a standard FHIR operation, the standard operation SHOULD be used.

FHIR-OPER-02 Define new FHIR operation when needed

• More complex and behaviours involving updates to multiple resources or complex querying or composition of resources MAY use an RPC-style FHIR Operation.

Health Services

FHIR-SERV-01 FHIR resource base Paths

• National FHIR resources MUST use consistent basePaths.