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5.6 Resource CompartmentDefinition - Content

FHIR Infrastructure Work Group

Maturity Level: 1

Trial Use

Compartments: Not linked to any defined compartments

A compartment definition that defines how resources are accessed on a server.

This resource is referenced by capabilitystatement

5.6.3 Resource Content

 

Alternate definitions: Master Definition XML + JSON, XML Schema/Schematron + JSON Schema, ShEx (for Turtle) + see the extensions & the dependency analysis

5.6.3.1 Terminology Bindings

Path	Definition	Type	Reference
CompartmentDefinition.status	The lifecycle status of an artifact.	Required	PublicationStatus
CompartmentDefinition.jurisdiction	Countries and regions within which this artifact is targeted for use	Extensible	Jurisdiction ValueSet
CompartmentDefinition.code	Which compartment a compartment definition describes	Required	CompartmentType
CompartmentDefinition.resource.code	One of the resource types defined as part of this version of FHIR.	Required	Resource Types

5.6.3.2 Using Compartments

As an example of compartment usage, to retrieve a list of a patient's conditions, use the URL:

  GET [base]/Patient/[id]/Condition

Additional search parameters can be defined, such as this hypothetical search for acute conditions:

  GET [base]/Patient/[id]/Condition?code:in=http://hspc.org/ValueSet/acute-concerns

Note that as searches, these are syntactic variations on these two search URLs respectively:

  GET [base]/Condition?patient=[id]
  GET [base]/Condition?patient=[id]&code:in=http://hspc.org/ValueSet/acute-concerns

The outcome of a compartment search is the same as the equivalent normal search. For example, both these searches return the same outcome if there is no patient 333:

  GET [base]/Patient/333/Condition
  GET [base]/Condition?patient=333

Whether the patient doesn't exist, or the user has no access to the patient, both these searches return an empty bundle with no matches. Some systems will include an operation outcome warning that there is no matching patient.

However, there is a key difference in functionality between compartment based searches and direct searches with parameters. Consider this search:

  GET [base]/Patient/[id]/Communication

Because the definition of the patient compartment for Communication says that a Communication resource is in the patient compartment if the subject, sender, or recipient is the patient, the compartment search is actually the same as the union of these 3 searches:

  GET [base]/Communication?subject=[id]
  GET [base]/Communication?sender=[id]
  GET [base]/Communication?recipient=[id]

There is no way to do this as a single search, except by using the _filter:

  GET [base]/Communication?_filter=subject re [id] or sender re [id] or recipient re [id]

Further details of searching by compartment are described under the search operation. As a search related operation, the assignment of resources to compartments is only based on the current version of any of the resources involved. Note that contained patient resources cannot create a patient compartment of their own.

Note that this specification describes using the compartment syntax to find resources that are logically associated with the compartment, the compartment is not part of the identity of the resource. E.g. the response to the following is not defined by this specification:

  GET [base]/Patient/[patient-id]/Condition/[resource-id]

The response for write operations (PUT/DELETE/PATCH) are also not defined by this specification. Nor is the response to a POST defined:

  POST [base]/Patient/[patient-id]/Condition

There is no expectation for servers to support either read or write to such URLs.

5.6.3.3 Logical Meaning of Compartments

Compartments may be used explicitly, like this, but can also be used implicitly. For instance, if a FHIR server is providing a patient view of a record, the authorized user associated with use of the FHIR RESTful API may be limited to accessing records from the compartment instance(s) logically associated with their identity. Irrespective of whether compartments are being used explicitly or implicitly, servers will need to make arrangements to make some resources with no direct link to a patient available to the client (medications, substances, etc.).

Note that resources may cross between compartments, or interlink them. Examples of this would be where a Diagnostic Report identifies a subject, but an Observation it references identifies a different subject, or where a List resource references items that identify different subjects. Such cross-linking may arise for many valid reasons, including:

• Cases where subject records are inter-linked - Transplants, Perinatal care, family therapy etc.
• Workflow management where action lists link multiple patients and/or practitioners

Given the wide variety of use cases and contexts in which FHIR is used, compartments do not define how cross-linking is handled. Systems may reject resources, remove them from both compartments, or place them in both, or act in some other fashion.

The graph definition resource provides a method by which rules about cross-linking may be made and enforced.

It is at the discretion of the server whether to include resources in a compartment when the reference to the resource that establishes the compartment is in an extension.

Some resources are not in any compartment, e.g. Medication, Substance, Location. These resources are not directly to a patient or authored record, and are sometimes called 'master files'. Servers will need to make arrangements to make these resources available to the clients that are limited to particular compartments. For example, a Medication resource describes a medication itself and does not link to a patient; however, a resource such as MedicationAdministration connects the Medication (details of what was administered) to the patient (for whom was it administered), and so is required to interpret the administration.

5.6.4 Defining New Compartments

Compartments are defined and added the list above when implementer communities identify them as common access points for data. As described below, compartments have both syntactical and logical consequences, and both these aspects of their functionality are evaluated when deciding whether to define compartments.

5.6.5 Search Parameters

Search parameters for this resource. The common parameters also apply. See Searching for more information about searching in REST, messaging, and services.

Name	Type	Description	Expression	In Common
code	token	Patient | Encounter | RelatedPerson | Practitioner | Device	CompartmentDefinition.code
context-type	token	A type of use context assigned to the compartment definition	CompartmentDefinition.useContext.code
date	date	The compartment definition publication date	CompartmentDefinition.date
description	string	The description of the compartment definition	CompartmentDefinition.description
jurisdiction	token	Intended jurisdiction for the compartment definition	CompartmentDefinition.jurisdiction
name	string	Computationally friendly name of the compartment definition	CompartmentDefinition.name
publisher	string	Name of the publisher of the compartment definition	CompartmentDefinition.publisher
resource	token	Name of resource type	CompartmentDefinition.resource.code
status	token	The current status of the compartment definition	CompartmentDefinition.status
title	string	The human-friendly name of the compartment definition	CompartmentDefinition.title
url	uri	The uri that identifies the compartment definition	CompartmentDefinition.url