Profiles Reference

This section provides a normative reference for the HSDS Profiles mechanism. If you are looking for guidance on how to use or implement a HSDS Profile, please see the Using Profiles page.

As an international standard, HSDS provides a common core of defintions and objects for describing health, human, and social services as well as their locations and the organizations that provide them. This allows HSDS to acommodate a wide range of applications and provide value in a variety of use cases.

Being an international standard, however, means that the needs of HSDS publishers and users are often significantly variable across varying contexts. In different geographies, sectors, and scenarios of usage, users MAY need different information about services, locations, and organizations.

To this end, HSDS provides the following Profiles Specification. HSDS Profiles can be specified as a series of changes from the HSDS Specification to address specific or local contexts.

As per the Conformance section, a publication is considered conformant to HSDS if it is conformant to a valid HSDS Profile as specified in this reference.

Profiles Specification

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in RFC 2119.

Profile URLs

Profiles MUST provide a URI (RFC 3986) which resolves to a canonical resource describing the Profile.

When implementing modifications to the HSDS API Specification file, Profiles SHOULD specify that the response object to the / API endpoint includes this URI as the value of the profile property. This is so that HSDS publications can declare the Profile they are conformant to.

Specification format

Profile specifications MUST be implemented as a set of files which describe modifications to existing HSDS specification files as defined in files available in the HSDS schema directory at the following canonical URL:

In the case of object schemas (e.g. service.json, organization.json, phone.json, etc.), modifications MUST be implemented so that they produce valid JSON Schema — i.e. conformant with the JSON Schema Draft 2020-12 Core/Validation metaschema — when merged with the corresponding schema defining an object in HSDS by means of a JSON Merge Patch (RFC 7386). A modification MUST be implemented in a file with the same filename as the corresponding schema in HSDS which it is intended to modify.

For example, a Profile describing a modification to HSDS’ service definition file MUST define these modifications in a file named service.json. When merging this with HSDS’ canonical service.json file via a process conforming to RFC 7386, the result MUST be a valid JSON Schema which validates against the JSON Schema Draft 2020-12 Core/Validation metaschema defined at:

In the case of the API specification file (openapi.json), modifications MUST be implemented so that the result of merging them with the HSDS OpenAPI specification file produces a result that is conformant to the OpenAPI 3.1 Specification. As with the modifications to schema files, the modification to the API specification file MUST be named to correspond with the API specification in HSDS (currently openapi.json).

Profile specifications MUST make these files available via publically accessible URIs which return the files. Profiles SHOULD implement the modifications under a /profile endpoint accessible underneath their canonical URI as described in the previous section. In addition, Profiles SHOULD pre-generate full Profile schemas by performing the JSON Merge Patch process using their defined modifications and retrieving copies of the canonical HSDS schemas, and make these available under a /schema endpoint accessible underneath their canonical URI. In both cases the /profile and /schema endpoints MAY each be implemented so that the URI is a result of a directory structure or it MAY be a logical endpoint defined by configuring a web server or a web framework.

The motivation for providing pre-generated schema files is to support tooling retrieving these for conformance checks against the Profile. However, tooling MAY be configured to retrieve the modifications and perform the JSON Merge patch itself. Tooling MAY perform both operations to compare results, and if the results are in conflict then the results derived from the Profile schemas MUST take precedence.

Given the prevalence of large-scale public code repositories such as Github and, Profiles MAY store the modifications inside a /profile directory of their repository and use the public URI for the repository as their canonical URI. In this event, tools SHOULD transform the canonical URI so that the raw files can be retrieved. For example a Profile with the canonical URI MAY provide its modifications to service.json under the following URI: while the modifications to openapi.json would be available under: in the same implementation. Given this, Profiles MAY store the generated schemas inside a /schema directory of the repository. The the compiled versions of these files would be available under the following URIs: for the service.json representing the Profile’s specification for a service and for openapi.json representing the Profile’s API Specification.

Profile Versioning

Profiles MAY choose any versioning scheme that is deemed suitable, but it is RECOMMENDED to use Semantic Versioning.

Profiles SHOULD be versioned independently of HSDS. For example if Profile A is derived from HSDS 3.0 then the Profile A SHOULD NOT be said to be Profile A 3.0 unless its own version increments to 3.0 through its own upgrade and governance processes.

Profiles SHOULD adapt to upgrades in HSDS, which MAY be considered as ‘upstream’ for these purposes, however they MAY also choose to ignore these upgrades. When a Profile adapts to changes in HSDS, it SHOULD update its own version number according to its versioning and governance processes.

Worked Example:

  1. A new HSDS Profile, Profile A is released. It is based off of HSDS 3.0, however its internal version is 1.0 and it uses Semantic Versioning.

  2. Profile A develops new features independant of HSDS, which are considered MINOR changes to the Profile, and upgrades itself accordingly to version 1.1.

  3. HSDS 3.1 is released, incorporating some MINOR changes of its own which are considered desirable for Profile A. These changes also represent MINOR changes from the perspective of Profile A, so after bringing these changes through from HSDS 3.1, Profile A is now on version 1.2.

  4. Some time later, HSDS 3.2 is released which adds further MINOR changes to HSDS. These changes respond to similar demands as Profile A so implement some comparable features, but in a slightly different way that is mutually incompatible with the features of Profile A. Profile A is still relevant as it provides additional features and adaptions not represented in HSDS 3.2. After engagement with the community, the developers of Profile A decide that it would be best to maintain interoperability with HSDS 3.2 and adapt Profile A to these changes. They bring through the changes from HSDS 3.2 which replace some features of Profile A, representing a MAJOR change which is not backwards compatible for users of Profile A 1.2. Profile A is now on version 2.0, being based on HSDS 3.2.

Permitted Modifications

Profiles are permitted a generous set of operations against the HSDS Specification which enables them to both extend and override it. Overriding MAY include changing the way properties or validation rules behave or removing them entirely.

Extending the HSDS Specification

A Profile MAY:

  • Add new optional or required properties to its specification. These SHOULD NOT overlap with terms already defined in HSDS.

  • Add new validation rules to its specification, including making existing HSDS properties ‘required’ and stipulating patterns or formats for conformance on existing HSDS properties.

  • Add new objects to its specification. These SHOULD NOT overlap with the semantics of objects already defined in HSDS.

  • Add new API endpoints to its API specification. These SHOULD NOT overlap with the intended use of API Endpoints defined in the HSDS API specification.

  • Recommend or require the use of particular value sets such as taxonomies or enumerations.

Overriding the HSDS Specification

A Profile MAY:

  • remove properties and their validation rules from the HSDS specifications by overriding their definitions with null. These MUST NOT then be replaced by alternative properties which have the same semantics as the removed properties.

  • remove entire objects from the HSDS Specification by overriding its object schema with null. These MUST NOT then be replaced by alternative objects which have the same semantics as the removed object.

  • remove API endpoints from the API specification by overriding their definitions with null. These MUST NOT bee replaced by alternative API endpoints which return the same values and take the same parameters as the removed endpoints.

  • override constraints on HSDS properties (e.g. string format requirements) by defining new constraints which will replace those defined in the HSDS Specification.

Serializing to Tabular Data Packages

Profiles SHOULD support serialization to a Tabular Data Package format.

This SHOULD be done by providing a datapackage.json file conformant to the Frictionless Tabular Data Package schema, which describes the serialization of the Profile accurately. Profiles MAY choose to implement this separately, but it is RECOMMENDED that Profiles generate this from schema files which result from compiling their modifications with the HSDS specification files via the JSON Merge patch.

Reference Implementation

There are two resources which comprise a Reference Implementation of the above specification.

  • The HSDS Schema Tools utility provides a profile-all command which will generate Profile schemas from a directory of modifications, performing the merge procedure with the canonical HSDS specification files automatically. It will also generate a datapackage.json file for supporting serializing to Tabular Data Packages.

  • The HSDS Example Profile Repository uses the mechanism provided by the HSDS Schema Tools to generate Profile schemas and a datapackage.json file, alongside documentation.