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Metadata Transform

Applies JOLT transformations to request metadata (key-value pairs used for routing decisions).

Configuration​

[middleware.fhir_dimse_meta]
type = "metadata_transform"
[middleware.fhir_dimse_meta.options]
spec_path = "transforms/metadata_set_dimse_op.json"
apply = "left"
fail_on_error = true

Options​

  • spec_path (string, required) - Path to JOLT specification file
  • apply (string, optional) - When to apply: "left", "right", or "both" (default: "left")
  • fail_on_error (bool, optional) - Whether to fail on transform errors (default: true)

Behavior​

  • Converts metadata to JSON for JOLT processing
  • Only string-valued outputs are written back to metadata
  • Preserves existing metadata fields not modified by transform
  • Common use case: setting dimse_op field to control DICOM operations

Example pipeline​

[pipelines.fhir_to_dicom]
description = "FHIR to DICOM bridge with metadata routing"
networks = ["default"]
endpoints = ["fhir_api"]
middleware = ["set_dicom_op"]
backends = ["dicom_scp"]

[endpoints.fhir_api]
service = "http"

[middleware.set_dicom_op]
type = "metadata_transform"
[middleware.set_dicom_op.options]
spec_path = "transforms/metadata_set_dimse_op.json"
apply = "left"

[backends.dicom_scp]
service = "dicom_scp"