Overview:

The $viewdefinition-export operation is an asynchronous operation that enables the bulk export of FHIR data that has been transformed using ViewDefinitions. Multiple ViewDefinitions can be exported in a single operation, allowing efficient batch processing of related views. Exported data can be written in various formats (CSV, NDJSON, Parquet) and delivered to file storage systems such as Amazon S3, Azure Blob Storage, or a local file system.

Use Cases:

• Large-scale data extraction for analytics and reporting
• Loading transformed FHIR data into data warehouses
• Batch processing of ViewDefinition transformations
• Exporting filtered subsets of transformed data

Endpoints:

• {BaseUrl}/$viewdefinition-export (system level)
• {BaseUrl}/ViewDefinition/$viewdefinition-export (type level)
• {BaseUrl}/ViewDefinition/{id}/$viewdefinition-export (instance level)

URL: [base]/$viewdefinition-export

URL: [base]/CanonicalResource/$viewdefinition-export

URL: [base]/CanonicalResource/[id]/$viewdefinition-export

Parameters

HTTP Methods

• POST: Required for providing export parameters and ViewDefinitions

Asynchronous Pattern

This operation follows the FHIR Asynchronous Bulk Data Request Pattern; the completion response is specified once in Common Operation Behavior — Asynchronous Delivery:

1. Client sends request with Prefer: respond-async header and one or more view parameters
2. Server returns 202 Accepted with Content-Location header pointing to status URL
3. Client polls the status URL for export progress
4. Server responds with 202 Accepted while export is in progress (MAY include interim results)
5. Upon completion, the status poll returns 200 OK with the manifest Parameters resource (exportId, status, output, …) in the response body
6. Client downloads the exported files from the output.location URLs in the manifest

Note: This operation uses a FHIR Parameters resource as the manifest instead of the Bulk Data JSON manifest object to:

• Provide structured status reporting and metadata
• Allow extensible output metadata specific to export operations
• Maintain consistency with other FHIR operations

Note: Completion is signalled by 200 OK with the manifest in the body of the status-poll response, as in the FHIR Asynchronous Bulk Data Request Pattern. The operation does not use a 303 See Other redirect to a separate result resource, so standard Bulk Data clients interoperate without special handling.

Async Flow Diagram

    Client                                          Server
      │                                               │
      │ ┌─────────────────────────────────────────┐   │
      │ │ POST /ViewDefinition/$viewdefinition-export│
      │ │ Content-Type: application/fhir+json     │   │
      │ │ Prefer: respond-async                   │   │
      │ │ Accept: application/fhir+json           │   │
      │ │                                         │   │
      │ │ { "resourceType": "Parameters",         │   │
      │ │   "parameter": [                        │   │
      │ │     {"name": "view", "part": [...]}     │   │
      │ │   ]}                                    │   │
      │ └─────────────────────────────────────────┘   │
      │ ─────────────────────────────────────────────>│
      │                                               │  Step 1: Kick-off
      │   ┌─────────────────────────────────────────┐ │
      │   │ 202 Accepted                            │ │
      │   │ Content-Location: /status/abc123        │ │
      │   │                                         │ │
      │   │ { "resourceType": "Parameters",         │ │
      │   │   "parameter": [                        │ │
      │   │     {"name": "exportId",                │ │
      │   │      "valueString": "abc123"},          │ │
      │   │     {"name": "status",                  │ │
      │   │      "valueCode": "accepted"}           │ │
      │   │   ]}                                    │ │
      │   └─────────────────────────────────────────┘ │
      │ <─────────────────────────────────────────────│
      │                                               │
      ├ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─┤
      │                                               │
      │ ┌─────────────────────────────────────────┐   │
      │ │ GET /status/abc123                      │   │
      │ │ Accept: application/fhir+json           │   │
      │ └─────────────────────────────────────────┘   │
      │ ─────────────────────────────────────────────>│
      │                                               │  Step 2: Polling
      │   ┌─────────────────────────────────────────┐ │  (repeat while
      │   │ 202 Accepted                            │ │   in progress)
      │   │ Retry-After: 10                         │ │
      │   │ X-Progress: 45%                         │ │
      │   │                                         │ │
      │   │ { "resourceType": "Parameters",         │ │
      │   │   "parameter": [                        │ │
      │   │     {"name": "status",                  │ │
      │   │      "valueCode": "in-progress"}        │ │
      │   │   ]}                                    │ │
      │   └─────────────────────────────────────────┘ │
      │ <─────────────────────────────────────────────│
      │                 ... (repeat) ...              │
      │                                               │
      ├ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─┤
      │                                               │
      │ ┌─────────────────────────────────────────┐   │
      │ │ GET /status/abc123                      │   │
      │ │ Accept: application/fhir+json           │   │
      │ └─────────────────────────────────────────┘   │
      │ ─────────────────────────────────────────────>│
      │                                               │  Step 3: Completion
      │   ┌─────────────────────────────────────────┐ │  (200 OK + manifest)
      │   │ 200 OK                                  │ │
      │   │ Content-Type: application/fhir+json    │ │
      │   │ Expires: Mon, 21 Jan 2026 16:00:00 GMT │ │
      │   │                                         │ │
      │   │ { "resourceType": "Parameters",         │ │
      │   │   "parameter": [                        │ │
      │   │     {"name": "status",                  │ │
      │   │      "valueCode": "completed"},         │ │
      │   │     {"name": "output", "part": [        │ │
      │   │       {"name": "name",                  │ │
      │   │        "valueString": "patients"},      │ │
      │   │       {"name": "location",              │ │
      │   │        "valueUrl": "/export/.../..."}   │ │
      │   │     ]}                                  │ │
      │   │   ]}                                    │ │
      │   └─────────────────────────────────────────┘ │
      │ <─────────────────────────────────────────────│
      │                                               │
      ├ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─┤
      │                                               │
      │ ┌─────────────────────────────────────────┐   │
      │ │ GET /export/abc123/patients.ndjson      │   │
      │ └─────────────────────────────────────────┘   │
      │ ─────────────────────────────────────────────>│
      │                                               │  Step 4: Download
      │   ┌─────────────────────────────────────────┐ │
      │   │ 200 OK                                  │ │
      │   │ Content-Type: application/x-ndjson     │ │
      │   │                                         │ │
      │   │ {"id":"pt1","name":[{"given":["John"]}]}│ │
      │   │ {"id":"pt2","name":[{"given":["Jane"]}]}│ │
      │   └─────────────────────────────────────────┘ │
      │ <─────────────────────────────────────────────│
      │                                               │

Alternative Flows:

  ┌─────────────────────────────────────────────────────────────────┐
  │  CANCELLATION (Recommended)                                      │
  ├─────────────────────────────────────────────────────────────────┤
  │                                                                 │
  │  Client                                          Server         │
  │    │                                               │            │
  │    │ DELETE /status/abc123                         │            │
  │    │ ─────────────────────────────────────────────>│            │
  │    │                                               │            │
  │    │   202 Accepted                                │            │
  │    │ <─────────────────────────────────────────────│            │
  │    │                                               │            │
  │    │ GET /status/abc123  (subsequent poll)         │            │
  │    │ ─────────────────────────────────────────────>│            │
  │    │                                               │            │
  │    │   404 Not Found                               │            │
  │    │ <─────────────────────────────────────────────│            │
  │                                                                 │
  └─────────────────────────────────────────────────────────────────┘

  ┌─────────────────────────────────────────────────────────────────┐
  │  ERROR HANDLING (Operation Failure)                             │
  ├─────────────────────────────────────────────────────────────────┤
  │                                                                 │
  │  Client                                          Server         │
  │    │                                               │            │
  │    │ GET /status/abc123                            │            │
  │    │ ─────────────────────────────────────────────>│            │
  │    │                                               │            │
  │    │   500 Internal Server Error                   │            │
  │    │   { "resourceType": "OperationOutcome",       │            │
  │    │     "issue": [{                               │            │
  │    │       "severity": "error",                    │            │
  │    │       "code": "exception",                    │            │
  │    │       "diagnostics": "Export failed: ..."     │            │
  │    │     }]}                                       │            │
  │    │ <─────────────────────────────────────────────│            │
  │                                                                 │
  └─────────────────────────────────────────────────────────────────┘

Data Sources

The operation can export data from:

1. Server resources - From the server’s data store (default)
2. External source - Specified via source parameter

Filtering

Optional filtering parameters:

• patient - Export only resources for this patient
• group - Export only resources for this group
• _since - Export only resources updated since this time

Required Headers

Kick-off Request

• Prefer: respond-async (required) - Specifies that the response should be asynchronous
• Accept (recommended) - Specifies the format of the kick-off response

Status Request

• Accept (recommended) - Specifies the format of the status response, including the completion (200 OK) response that carries the manifest

Header Scope

Each status-poll request’s headers apply to that poll’s response. Because completion is delivered as 200 OK with the manifest in the body of the status-poll response (there is no separate result resource), the Accept header sent on the completing poll governs the representation of the manifest. This allows a client to negotiate a different representation for interim status responses (e.g. minimal JSON) than for the final manifest if it chooses.

Parameters

Input Parameters

Core Parameters

ViewDefinition Parameter

The view parameter is a complex type that can be repeated multiple times to export several ViewDefinitions in a single operation. Each view parameter has the following parts:

¹ Either view.viewReference or view.viewResource is required

Export Control

Filtering

Data Source

If server does not support a parameter, request should be rejected with 400 Bad Request and OperationOutcome resource in the body with clarification that the parameter is not supported. Server should document which parameters it supports in its CapabilityStatement.

ViewReference Clarification

The view.viewReference parameter MAY be specified using any of the following formats:

• A relative URL on the server (e.g. “ViewDefinition/123”)

• A canonical URL (e.g. “http://specification.org/fhir/ViewDefinition/123

  1.0.0”)

• An absolute URL (e.g. “http://example.org/fhir/ViewDefinition/123”)

Servers MAY choose which reference formats they support. Servers SHALL document which reference formats they support in their CapabilityStatement.

For servers that want to support all types of references, it is recommended to follow the following algorithm:

1. If the reference is a relative URL, resolve it on the server side.
2. If the reference is an absolute URL, look up the available server Artifact registry for a resource with the same canonical URL and version if provided.
3. Otherwise, try to load the ViewDefinition from the provided absolute URL.

Format Parameter Clarification

The supported formats (json, ndjson, csv, parquet) and the default are defined in Common Operation Behavior and apply to this operation. The fhir format is available on the run operations only:

• It is RECOMMENDED to support json, ndjson and csv by default; servers MAY support parquet, and SHALL document supported formats in the CapabilityStatement.
• If _format is omitted, the server SHALL produce the export output in ndjson format.
• When _format is supplied, its value SHALL take precedence over Accept (which here negotiates the format of the status/manifest responses, not the exported files).

Patient Parameter Clarification

When provided, the server SHALL NOT return resources in the patient compartments belonging to patients outside of this list.

If a client requests patients who are not present on the server, the server SHOULD return details via a FHIR OperationOutcome resource in an error response to the request.

Group Parameter Clarification

When provided, the server SHALL NOT return resources that are not a member of the supplied Group.

If a client requests groups that are not present on the server, the server SHOULD return details via a FHIR OperationOutcome resource in an error response to the request.

Since Parameter Clarification

Resources will be included in the response if their state has changed after the supplied time (e.g., if Resource.meta.lastUpdated is later than the supplied _since time). In the case of a Group level export, the server MAY return additional resources modified prior to the supplied time if the resources belong to the patient compartment of a patient added to the Group after the supplied time (this behavior SHOULD be clearly documented by the server). For Patient- and Group-level requests, the server MAY return resources that are referenced by the resources being returned regardless of when the referenced resources were last updated. For resources where the server does not maintain a last updated time, the server MAY include these resources in a response irrespective of the _since value supplied by a client.

Output Parameters

Output parameters appear in the completion response — the 200 OK status-poll response that carries the manifest. They are not present in the 202 Accepted responses returned while the export is still in progress.

Export Identifiers

Export Metadata

Export Results

Status Polling Parameters (interim)

During status polling (202 Accepted responses), servers MAY include the following in the response body:

Servers MAY also include partial/interim results during polling. The format of interim responses is implementation-defined.

Output Name Clarification

The output.name parameter identifies each exported view in the results. The value is determined as follows:

1. If view.name was provided in the input parameters, that value is used
2. If view.name was not provided, the name is taken from the ViewDefinition resource’s name element
3. If neither is available, the server SHALL generate a unique identifier for the output

This allows clients to correlate output files with their requested views and provides meaningful filenames for the exported data.

Output Partitioning

For large exports, servers MAY partition the output into multiple files. When partitioning occurs:

1. Multiple Locations: The output.location parameter can repeat within a single output entry
2. File Naming: Partitioned files SHOULD use a consistent naming convention (e.g., filename.part1.parquet, filename.part2.parquet)
3. Complete Set: All parts together represent the complete export for that view

Example of partitioned output:

{
    "name": "output",
    "part": [
        {
            "name": "name",
            "valueString": "patient_demographics"
        },
        {
            "name": "location",
            "valueUri": "https://example.com/export/123/patient_demographics.part1.parquet"
        },
        {
            "name": "location",
            "valueUri": "https://example.com/export/123/patient_demographics.part2.parquet"
        },
        {
            "name": "location",
            "valueUri": "https://example.com/export/123/patient_demographics.part3.parquet"
        }
    ]
}

Clients MUST download all parts to obtain the complete dataset for a view.

Error Handling

HTTP Status Codes

The $viewdefinition-export operation uses standard HTTP status codes to indicate the outcome:

All error responses (4xx and 5xx) SHOULD include an OperationOutcome resource providing details about the error.

Common Error Scenarios

1. Unsupported Parameters

When the server does not support certain parameters, it returns 400 Bad Request:

HTTP/1.1 400 Bad Request
Content-Type: application/fhir+json

{
  "resourceType": "OperationOutcome",
  "issue": [
    {
      "severity": "error",
      "code": "not-supported",
      "diagnostics": "The server does not support the 'source' parameter"
    }
  ]
}

2. Invalid ViewDefinition

When a provided ViewDefinition is invalid:

HTTP/1.1 422 Unprocessable Entity
Content-Type: application/fhir+json

{
  "resourceType": "OperationOutcome",
  "issue": [
    {
      "severity": "error",
      "code": "invalid",
      "diagnostics": "The ViewDefinition 'patient_summary' is invalid: column 'age' contains invalid FHIRPath expression",
      "expression": ["parameter[0].part[1].resource.select[0].column[1].path"]
    }
  ]
}

3. ViewDefinition Not Found

When a referenced ViewDefinition does not exist:

HTTP/1.1 404 Not Found
Content-Type: application/fhir+json

{
  "resourceType": "OperationOutcome",
  "issue": [
    {
      "severity": "error",
      "code": "not-found",
      "diagnostics": "ViewDefinition with reference 'ViewDefinition/non-existent' not found"
    }
  ]
}

4. Patient or Group Not Found

When filtering by patient or group that doesn’t exist:

HTTP/1.1 404 Not Found
Content-Type: application/fhir+json

{
  "resourceType": "OperationOutcome",
  "issue": [
    {
      "severity": "error",
      "code": "not-found",
      "diagnostics": "Patient with reference 'Patient/12345' not found"
    }
  ]
}

For group references:

HTTP/1.1 404 Not Found
Content-Type: application/fhir+json

{
  "resourceType": "OperationOutcome",
  "issue": [
    {
      "severity": "error",
      "code": "not-found",
      "diagnostics": "Group with reference 'Group/diabetes-cohort' not found"
    }
  ]
}

5. Multiple ViewDefinitions with Errors

When processing multiple ViewDefinitions, servers SHOULD validate all of them before starting the export:

HTTP/1.1 400 Bad Request
Content-Type: application/fhir+json

{
  "resourceType": "OperationOutcome",
  "issue": [
    {
      "severity": "error",
      "code": "not-found",
      "diagnostics": "ViewDefinition 'patient-vitals' not found",
      "expression": ["parameter[1]"]
    },
    {
      "severity": "error",
      "code": "invalid",
      "diagnostics": "ViewDefinition 'lab-results' contains invalid resource type",
      "expression": ["parameter[2]"]
    }
  ]
}

Operation flow

1. Kick-off Request: Client sends POST ViewDefinition/$viewdefinition-export with Prefer: respond-async header.
2. Kick-off Response: Server responds with:
   • 202 Accepted status code
   • Content-Location header with the absolute URL for subsequent status requests (polling location)
   • Parameters resource with status parameter set to accepted and location parameter
   • If request is not valid or cannot be processed, server responds with 400 Bad Request and OperationOutcome resource in the body.
3. Status Polling: Client polls the polling location to get status of the export:
   • In Progress: 202 Accepted with optional Parameters resource for interim status
   • Progress Updates: Server MAY include X-Progress header to indicate completion percentage
   • Retry-After: Server SHOULD include Retry-After header to indicate when to retry
   • Interim Results: Server MAY include partial/interim results in response body (implementation-defined)
4. Completion: When the export is ready, the status poll returns:
   • 200 OK status code
   • A Parameters resource in the body containing status = completed, the export metadata, and the output entries with their download locations
   • This is the same manifest a synchronous call would return; there is no 303 See Other redirect and no separate result URL
5. Error Handling: If the export fails, the status poll returns the relevant error status code (e.g. 500 Internal Server Error) with an OperationOutcome body. Polling-transport errors and operation failures are distinguished by the status code on the poll response itself.
6. Cancellation (Recommended): Servers SHOULD support export cancellation via DELETE request to the status URL:
   • Client sends DELETE request to the status polling URL
   • Server responds with 202 Accepted
   • Subsequent status requests return 404 Not Found
   • Server SHOULD clean up any partial results
7. Result Lifetime: The completed status URL (which returns the manifest) and the output.location download URLs SHALL remain valid for at least 24 hours after export completion:
   • Servers SHOULD support multiple retrievals of the completed manifest
   • Servers MAY include an Expires header to indicate when the URLs expire
   • Clients should retrieve results promptly but can retry within the validity window
8. Access Control: Servers SHALL protect status and download URLs with appropriate access controls:
   • Same authorization context as the original request, OR
   • Non-guessable URLs (e.g., cryptographically random tokens)
   • Unauthorized access attempts return 401 Unauthorized or 403 Forbidden
9. File Download: Client downloads the output from URLs in the output.location parameters.

Examples

Complete Export Flow Example

This example demonstrates the full lifecycle of an export operation from initiation through completion.

Step 1: Kick-off Request

Client initiates export of two ViewDefinitions with patient filtering:

POST /ViewDefinition/$viewdefinition-export HTTP/1.1
Host: example.com
Content-Type: application/fhir+json
Prefer: respond-async
Accept: application/fhir+json
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGc...

{
  "resourceType": "Parameters",
  "parameter": [
    {
      "name": "clientTrackingId",
      "valueString": "monthly-report-2026-01"
    },
    {
      "name": "view",
      "part": [
        {
          "name": "name",
          "valueString": "demographics_summary"
        },
        {
          "name": "viewReference",
          "valueReference": {
            "reference": "ViewDefinition/patient-demographics-v2"
          }
        }
      ]
    },
    {
      "name": "view",
      "part": [
        {
          "name": "viewResource",
          "resource": {
            "resourceType": "ViewDefinition",
            "name": "active_medications",
            "resource": "MedicationRequest",
            "select": [
              {
                "column": [
                  {
                    "path": "id",
                    "name": "medication_id"
                  },
                  {
                    "path": "medication.concept.coding[0].display",
                    "name": "medication_name"
                  },
                  {
                    "path": "authoredOn",
                    "name": "prescribed_date"
                  },
                  {
                    "path": "subject.reference",
                    "name": "patient_ref"
                  }
                ]
              }
            ],
            "where": [
              {
                "path": "status",
                "op": "=",
                "value": "active"
              }
            ]
          }
        }
      ]
    },
    {
      "name": "patient",
      "valueReference": {
        "reference": "Patient/cohort-123"
      }
    },
    {
      "name": "_since",
      "valueInstant": "2026-01-01T00:00:00Z"
    },
    {
      "name": "_format",
      "valueCode": "parquet"
    }
  ]
}

Step 2: Kick-off Response

Server accepts the request and provides polling location:

HTTP/1.1 202 Accepted
Content-Location: https://example.com/fhir/export/550e8400-e29b-41d4-a716-446655440000/status
Content-Type: application/fhir+json

{
  "resourceType": "Parameters",
  "parameter": [
    {
      "name": "exportId",
      "valueString": "550e8400-e29b-41d4-a716-446655440000"
    },
    {
      "name": "clientTrackingId",
      "valueString": "monthly-report-2026-01"
    },
    {
      "name": "status",
      "valueCode": "accepted"
    },
    {
      "name": "location",
      "valueUri": "https://example.com/fhir/export/550e8400-e29b-41d4-a716-446655440000/status"
    }
  ]
}

Step 3: First Status Poll (Starting)

Client polls immediately:

GET /fhir/export/550e8400-e29b-41d4-a716-446655440000/status HTTP/1.1
Host: example.com
Accept: application/fhir+json
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGc...

Response shows export is starting:

HTTP/1.1 202 Accepted
Content-Type: application/fhir+json
Retry-After: 5
X-Progress: 0%

{
  "resourceType": "Parameters",
  "parameter": [
    {
      "name": "exportId",
      "valueString": "550e8400-e29b-41d4-a716-446655440000"
    },
    {
      "name": "clientTrackingId",
      "valueString": "monthly-report-2026-01"
    },
    {
      "name": "status",
      "valueCode": "in-progress"
    },
    {
      "name": "location",
      "valueUri": "https://example.com/fhir/export/550e8400-e29b-41d4-a716-446655440000/status"
    },
    {
      "name": "exportStartTime",
      "valueInstant": "2026-01-15T14:30:00Z"
    }
  ]
}

Step 4: Second Status Poll (In Progress)

After 5 seconds, client polls again:

GET /fhir/export/550e8400-e29b-41d4-a716-446655440000/status HTTP/1.1
Host: example.com
Accept: application/fhir+json
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGc...

Response shows progress:

HTTP/1.1 202 Accepted
Content-Type: application/fhir+json
Retry-After: 10
X-Progress: 65%

{
  "resourceType": "Parameters",
  "parameter": [
    {
      "name": "exportId",
      "valueString": "550e8400-e29b-41d4-a716-446655440000"
    },
    {
      "name": "clientTrackingId",
      "valueString": "monthly-report-2026-01"
    },
    {
      "name": "status",
      "valueCode": "in-progress"
    },
    {
      "name": "location",
      "valueUri": "https://example.com/fhir/export/550e8400-e29b-41d4-a716-446655440000/status"
    },
    {
      "name": "exportStartTime",
      "valueInstant": "2026-01-15T14:30:00Z"
    },
    {
      "name": "estimatedTimeRemaining",
      "valueInteger": 25
    }
  ]
}

Step 5: Final Status Poll (Completed)

After another 10 seconds:

GET /fhir/export/550e8400-e29b-41d4-a716-446655440000/status HTTP/1.1
Host: example.com
Accept: application/fhir+json
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGc...

The status poll returns 200 OK with the manifest in the body (identical to what a synchronous call would return); there is no redirect:

HTTP/1.1 200 OK
Content-Type: application/fhir+json
Expires: Fri, 16 Jan 2026 14:30:42 GMT

{
  "resourceType": "Parameters",
  "parameter": [
    {
      "name": "exportId",
      "valueString": "550e8400-e29b-41d4-a716-446655440000"
    },
    {
      "name": "clientTrackingId",
      "valueString": "monthly-report-2026-01"
    },
    {
      "name": "status",
      "valueCode": "completed"
    },
    {
      "name": "_format",
      "valueCode": "parquet"
    },
    {
      "name": "exportStartTime",
      "valueInstant": "2026-01-15T14:30:00Z"
    },
    {
      "name": "exportEndTime",
      "valueInstant": "2026-01-15T14:30:42Z"
    },
    {
      "name": "exportDuration",
      "valueInteger": 42
    },
    {
      "name": "output",
      "part": [
        {
          "name": "name",
          "valueString": "demographics_summary"
        },
        {
          "name": "location",
          "valueUri": "https://example.com/fhir/export/550e8400-e29b-41d4-a716-446655440000/demographics_summary.parquet"
        }
      ]
    },
    {
      "name": "output",
      "part": [
        {
          "name": "name",
          "valueString": "active_medications"
        },
        {
          "name": "location",
          "valueUri": "https://example.com/fhir/export/550e8400-e29b-41d4-a716-446655440000/active_medications.part1.parquet"
        },
        {
          "name": "location",
          "valueUri": "https://example.com/fhir/export/550e8400-e29b-41d4-a716-446655440000/active_medications.part2.parquet"
        }
      ]
    }
  ]
}

Step 6: Download Files

Client downloads each file:

GET /fhir/export/550e8400-e29b-41d4-a716-446655440000/demographics_summary.parquet HTTP/1.1
Host: example.com
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGc...

HTTP/1.1 200 OK
Content-Type: application/octet-stream
Content-Disposition: attachment; filename="demographics_summary.parquet"
Content-Length: 1048576

[Binary parquet file content]