Using a fallback blueprint while using projects

When you use custom output with multiple blueprints, BDA attempts to match each document to the most appropriate blueprint. If no blueprint matches a document, BDA normally returns a customOutputStatus of NO_MATCH and no custom output is generated for that document. A fallback blueprint lets you specify a blueprint to use when no other blueprint matches, so you still receive custom output for every document.

How fallback blueprints work

When BDA processes a document and cannot match it to any of the blueprints in your project, the following occurs:

• Without a fallback blueprint — BDA returns customOutputStatus: NO_MATCH and no custom output for that document.

• With a fallback blueprint — If the result is NO_MATCH, BDA uses the fallback blueprint to extract custom output and returns customOutputStatus: FALLBACK.

This is useful when you have specialized blueprints for known document types but still want structured output for unexpected or miscellaneous documents.

Matching behavior with different blueprint configurations

The matching behavior and confidence scores depend on how many blueprints are in your project and whether a fallback blueprint is configured:

Configuration	Matching behavior	Confidence score
One blueprint, no fallback	BDA forces a match to the single blueprint without running the matcher.	Always 1.0
One blueprint, with fallback	BDA runs the matcher against the single blueprint. If the document does not match, BDA uses the fallback blueprint.	True score, or 0 if fallback is used
Multiple blueprints, no fallback	BDA runs the matcher against all blueprints and selects the best match. If no blueprint matches, returns NO_MATCH.	True score, or no custom output if no match
Multiple blueprints, with fallback	BDA runs the matcher against all blueprints and selects the best match. If no blueprint matches, BDA uses the fallback blueprint.	True score, or 0 if fallback is used

Adding a fallback blueprint enables actual match confidence scoring in all configurations. In the single-blueprint case without a fallback, BDA skips the matcher entirely and always forces a match. With a fallback configured, BDA runs the matcher and gives you visibility into how well documents actually match your blueprints.

Configuring a fallback blueprint

You configure a fallback blueprint in the customOutputConfiguration when creating or updating a project. The fallback blueprint is specified under the document field and accepts a single blueprint.

The following example creates a project with two regular blueprints and one fallback blueprint. For more information about the fallback blueprint configuration, see DocumentCustomOutputConfiguration in the API Reference.

Python SDK

response = client.create_data_automation_project(
    projectName=project_name,
    projectDescription="Provide a project description",
    projectStage='LIVE',
    standardOutputConfiguration=output_config,
    customOutputConfiguration={
        'blueprints': [
            {
                'blueprintArn': Blueprint ARN,
                'blueprintStage': 'LIVE'
            },
            ...
        ],
        'document': {
            'fallbackBlueprints': [
                {
                    'blueprintArn': Fallback Blueprint ARN,
                    'blueprintStage': 'LIVE'
                }
            ]
        }
    }
)
  

AWS CLI

aws bedrock-data-automation create-data-automation-project \
    --project-name project_name \
    --project-stage LIVE \
    --standard-output-configuration '{"document":{}}' \
    --custom-output-configuration '{
        "blueprints": [
            {
                "blueprintArn": "Blueprint ARN",
                "blueprintStage": "LIVE"
            }
        ],
        "document": {
            "fallbackBlueprints": [
                {
                    "blueprintArn": "Fallback Blueprint ARN",
                    "blueprintStage": "LIVE"
                }
            ]
        }
    }'
  

In this example, BDA first attempts to match each document to the invoice or receipt blueprint. If neither matches, BDA uses the general-document blueprint as a fallback.

Note

You can specify at most one fallback blueprint per project. Fallback blueprints are supported for the document modality only.

Understanding fallback output

The customOutputStatus field in the output indicates how the document was processed:

customOutputStatus	Description
MATCH	The document matched one of the regular blueprints in the project.
NO_MATCH	No blueprint matched and no fallback blueprint was configured.
FALLBACK	No regular blueprint matched, but the fallback blueprint was used to generate custom output.

The following is an example output snippet from the InvokeDataAutomationAsync API when a fallback blueprint is used:

{
  "semanticModality": "DOCUMENT",
  "outputSegments": [
    {
      "customOutputStatus": "FALLBACK",
      "standardOutput": {
        ...
      },
      "customOutput": {
        "matched_blueprint": {
          "arn": "arn:aws:bedrock:us-east-1:123456789012:blueprint/general-document",
          "version": "1",
          "name": "general-document",
          "confidence": 1.0
        },
        "inference_result": {
          ...
        }
      }
    }
  ]
}