Scope

This capability supports the ability to retrieve known documents using the document's resource id.

Use Cases

The following CA:FeX use cases leverage this capability:

CA:FeX Transactions

This capability describes the FHIR implementation of the CA:FeX Retrieve Data (CA:FeX-3) transaction found in the Sequence Diagram for UC:02: Query and Retrieve Document.

HTTP Operations

This capability can be leveraged using HTTP GET requests. Implementers are expected to familiarize themselves with how searches are executed using the FHIR RESTful API framework.

See CA:FeX Actors and Transactions for more information on the supported HTTP operations.

HTTP GET

In the simplest case, a retrieve is executed by performing a GET operation in the RESTful framework:

GET [base]/[resourcetype]/id

Considerations for Document Retrieve Patterns

This pattern is predicated on the requestor knowing the id of the resource they are attempting to retrieve. 

Depending on the maturity and scope of the repository, the endpoints supported may be isolated to [base]/Bundle but the repository could potentially support additional document formats which would be retrieved from different endpoints.

Guidance is provided below for early adopters of CA:FeX that will support the ability to retrieve FHIR Documents directly from a FHIR Assembled Documents Repository.

Note: The pattern intended for the retrieve from a FHIR Document Repository (CA:FeX 3A) has received significantly more rounds of feedback and projectathon testing than the pattern that was socialized for implementers retrieving documents from Hybrid Repositories (CA:FeX 3B). CA:FeX 3B has been migrated to a future release of the CA:FeX.

Document Retrieve Patterns

CA:FeX-3A (Retrieve Document From FHIR Assembled Documents Repository)

The most straightforward method to retrieve a FHIR Document is to perform a read interaction using HTTP GET  [base]/[type]/[resource id] against a[base]/Bundle endpoint.

Per the FHIR Standard on the HTTP read interaction:

  • This returns a single instance with the content specified for the resource type.
  • This URL may be accessed by a browser.
  • The possible values for the Logical Id ("id") itself are described in the id type.
  • The returned resource SHALL have an id element with a value that is the [id]. 

Considerations for Document Retrieve Using Bundle Endpoints

Anchoring retrievals around a Bundle endpoint in this retrieval pattern is recommended for implementers that want to retrieve the FHIR Document using the known id for the Bundle. This retrieval pattern is expected to be used by implementers re-retrieving a Bundle that was previously identified in a search/or prior retrieval.

Document Retrieve Patterns: Supported Retrieval Parameters

The following examples are used to retrieve documents based on a known resource ID.

GET [base]/Bundle/[id]

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