Value set operation $expand should not change the content of the base expansion and is not mature

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    • Type: Change Request
    • Resolution: Persuasive with Modification
    • Priority: Medium
    • FHIR Core (FHIR)
    • STU3
    • Terminology Infrastructure
    • Normative
    • ValueSet
    • Hide

      Update the documentation to clarify that If there is only an expansion and you are asked for an expansion with different parameters then this is an error (return OperationOutcome). If the parameters match then the existing expansion will be returned.

      Additional parameters may be applied to an existing expansion if the server has validated that the result will be the same as if the expansion was generated directly from the value set definition (e.g. text filter, designations included).

      Change the text to say:
      "The server decides which parameters to include here, but at a minimum, the list SHOULD include all of the parameters that affect the $expand operation. If the expansion will be persisted all of these parameters SHALL be included."

      Grahame will remove the ExpansionProfile resource and will redraft the $expand operation to ensure that the requirements are addressed and will bring back to Vocab WG for review.

      Will test this in the next Connectathon in Baltimore. Will also test the audit trail of expansion generation.

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      Update the documentation to clarify that If there is only an expansion and you are asked for an expansion with different parameters then this is an error (return OperationOutcome). If the parameters match then the existing expansion will be returned. Additional parameters may be applied to an existing expansion if the server has validated that the result will be the same as if the expansion was generated directly from the value set definition (e.g. text filter, designations included). Change the text to say: "The server decides which parameters to include here, but at a minimum, the list SHOULD include all of the parameters that affect the $expand operation. If the expansion will be persisted all of these parameters SHALL be included." Grahame will remove the ExpansionProfile resource and will redraft the $expand operation to ensure that the requirements are addressed and will bring back to Vocab WG for review. Will test this in the next Connectathon in Baltimore. Will also test the audit trail of expansion generation.
    • Grahame Grieve / Rob Hausam: 18-0-1
    • Correction
    • Non-compatible
    • STU3

      The $Expand operation supports the following parameters the are allowed to override the expansion as defined in the value set CLD. This wil.l result in value expansions that appear to be complete, yet have been restricted based upon the input parameters. These parametes are "filter", "activeOnly", profile, excludeNested, excludeNotForUI, excludePostCordinated, LimitedExpansion.

      These inputs act as "modifiers" to the expected expansion and as such are very dangerous for subsequent use of the expansion if the modifcation is clearly carried - forever - with the expansion to indicate the expansion has been modified.

      How to clarify this within the expansion result is not clear, but perhaps the input parameter list should be included in the Expansion result within the value set resource bundle returned.

      Also, allowing operation restirctions based on parameters to override expansion prametrs included within an expansion profile seems backwards from a typical "inside specifications" can not be overridden based on the assumption that an expansion profile is to be applied before any operation parameter specifications. Including this in a Normative track when expansion Profiles are not at the same maturity level is very dangerous.

      I think we need to do more work with this operation, particualrly with intersections of these parameters and use of expansion profiles before it is normative.

            Assignee:
            Unassigned
            Reporter:
            Rob McClure
            Rob McClure
            Watchers:
            1 Start watching this issue

              Created:
              Updated:
              Resolved: