Microsoft Excel Calculate with a Workbook Function and Write the Result

arazzo: 1.0.1
info:
  title: Microsoft Excel Calculate with a Workbook Function and Write the Result
  summary: Read input cells, invoke an Excel function as a calculation engine, and write the result back.
  description: >-
    This is the flow that makes Excel interesting as an API rather than as a
    file format: the workbook functions endpoint exposes Excel's own
    calculation engine over HTTP, so a caller can compute with the same PMT, NPV
    or lookup semantics a finance team already trusts, without reimplementing
    them. The flow reads the input range, calls the named function, checks the
    result carries no Excel error, and writes the value back into the workbook.
    Every step spells out its request inline so the flow can be read and
    executed without opening the underlying OpenAPI.
  version: 1.0.0
sourceDescriptions:
- name: functionsApi
  url: ../openapi/microsoft-excel-functions-api-openapi.yml
  type: openapi
- name: rangesApi
  url: ../openapi/microsoft-excel-ranges-api-openapi.yml
  type: openapi
- name: sessionsApi
  url: ../openapi/microsoft-excel-sessions-api-openapi.yml
  type: openapi
workflows:
- workflowId: workbook-function-calc
  summary: Invoke an Excel workbook function and persist its result into a cell.
  description: >-
    Reads the inputs backing a calculation, calls a named Excel function with
    the supplied parameters, verifies no function error was returned, and writes
    the computed value into a target cell.
  inputs:
    type: object
    required:
    - itemId
    - worksheetIdOrName
    - inputAddress
    - functionName
    - functionParameters
    - resultAddress
    properties:
      itemId:
        type: string
        description: The drive item id of the workbook file.
      worksheetIdOrName:
        type: string
        description: The worksheet holding the input and result cells.
      inputAddress:
        type: string
        description: >-
          The A1-notation range holding the values that back the calculation
          (e.g. "A1:A3").
      functionName:
        type: string
        description: The Excel function to invoke (e.g. "pmt", "npv", "vlookup").
      functionParameters:
        type: object
        description: >-
          The function's named parameters as key-value pairs, matching the
          argument names Excel expects (e.g. {"rate": 4.5, "nper": 12,
          "pv": -1250}).
      resultAddress:
        type: string
        description: The A1-notation single cell the computed value is written to (e.g. "B5").
  steps:
  - stepId: openSession
    description: >-
      Open a persisting session so the calculation reads a consistent view of
      the workbook and the written result is saved.
    operationId: createWorkbookSession
    parameters:
    - name: item-id
      in: path
      value: $inputs.itemId
    requestBody:
      contentType: application/json
      payload:
        persistChanges: true
    successCriteria:
    - condition: $statusCode == 201
    outputs:
      sessionId: $response.body#/id
  - stepId: readInputs
    description: >-
      Read the cells backing the calculation so the caller can record exactly
      which inputs produced the result that is about to be written.
    operationId: getRange
    parameters:
    - name: item-id
      in: path
      value: $inputs.itemId
    - name: worksheet-id-or-name
      in: path
      value: $inputs.worksheetIdOrName
    - name: address
      in: path
      value: $inputs.inputAddress
    - name: workbook-session-id
      in: header
      value: $steps.openSession.outputs.sessionId
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      inputValues: $response.body#/values
      inputFormulas: $response.body#/formulas
  - stepId: callFunction
    description: >-
      Invoke the named Excel function through the workbook functions endpoint.
      Excel returns a 200 with an error field set when the function itself
      fails, so a 200 alone is not proof of a usable result.
    operationId: callWorkbookFunction
    parameters:
    - name: item-id
      in: path
      value: $inputs.itemId
    - name: function-name
      in: path
      value: $inputs.functionName
    - name: workbook-session-id
      in: header
      value: $steps.openSession.outputs.sessionId
    requestBody:
      contentType: application/json
      payload: $inputs.functionParameters
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.error == null
      type: jsonpath
    outputs:
      functionValue: $response.body#/value
      functionError: $response.body#/error
  - stepId: writeResult
    description: >-
      Write the computed value into the target cell so the workbook carries the
      answer alongside the inputs that produced it.
    operationId: updateRange
    parameters:
    - name: item-id
      in: path
      value: $inputs.itemId
    - name: worksheet-id-or-name
      in: path
      value: $inputs.worksheetIdOrName
    - name: address
      in: path
      value: $inputs.resultAddress
    - name: workbook-session-id
      in: header
      value: $steps.openSession.outputs.sessionId
    requestBody:
      contentType: application/json
      payload:
        values:
        - - $steps.callFunction.outputs.functionValue
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      writtenAddress: $response.body#/address
      writtenValues: $response.body#/values
  outputs:
    inputValues: $steps.readInputs.outputs.inputValues
    functionValue: $steps.callFunction.outputs.functionValue
    writtenAddress: $steps.writeResult.outputs.writtenAddress