openapi: 3.1.0
info:
  title: OSIsoft PI Web AssetServers Streams API
  description: OSIsoft PI Web API (now part of AVEVA) provides a REST interface for accessing the PI System process historian. APIs enable real-time and historical time-series data retrieval, event frame queries, asset framework hierarchy navigation, and calculated data for industrial process monitoring.
  version: 2023.2.0
  contact:
    name: AVEVA Support
    url: https://softwaresupport.aveva.com
  license:
    name: AVEVA Software License
    url: https://www.aveva.com/legal/
servers:
- url: https://{piwebapi_host}/piwebapi
  description: PI Web API server
  variables:
    piwebapi_host:
      default: piwebapi.example.com
      description: PI Web API server hostname
security:
- basicAuth: []
- kerberos: []
tags:
- name: Streams
  description: Time-series data streams
paths:
  /streams/{webId}/value:
    get:
      operationId: getStreamValue
      summary: Get current stream value
      description: Returns the current (snapshot) value for a PI point or AF attribute stream.
      tags:
      - Streams
      parameters:
      - $ref: '#/components/parameters/WebId'
      - name: desiredUnits
        in: query
        description: Unit of measure for the returned value
        schema:
          type: string
      - name: selectedFields
        in: query
        schema:
          type: string
      responses:
        '200':
          description: Current stream value
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TimedValue'
        '404':
          $ref: '#/components/responses/NotFound'
  /streams/{webId}/recorded:
    get:
      operationId: getStreamRecorded
      summary: Get recorded stream values
      description: Returns archive (recorded) values for a PI point or AF attribute within a time range.
      tags:
      - Streams
      parameters:
      - $ref: '#/components/parameters/WebId'
      - name: startTime
        in: query
        description: Start time (absolute or relative, e.g. "*-1d" or "2026-03-01T00:00:00Z")
        schema:
          type: string
          default: '*-1d'
      - name: endTime
        in: query
        description: End time
        schema:
          type: string
          default: '*'
      - name: boundaryType
        in: query
        schema:
          type: string
          enum:
          - Inside
          - Outside
          - Interpolated
          default: Inside
      - name: maxCount
        in: query
        schema:
          type: integer
          default: 1000
      - name: desiredUnits
        in: query
        schema:
          type: string
      - name: selectedFields
        in: query
        schema:
          type: string
      responses:
        '200':
          description: Recorded values
          content:
            application/json:
              schema:
                type: object
                properties:
                  Items:
                    type: array
                    items:
                      $ref: '#/components/schemas/TimedValue'
                  Links:
                    $ref: '#/components/schemas/PaginationLinks'
        '404':
          $ref: '#/components/responses/NotFound'
  /streams/{webId}/interpolated:
    get:
      operationId: getStreamInterpolated
      summary: Get interpolated stream values
      description: Returns interpolated values at a fixed time interval within a time range.
      tags:
      - Streams
      parameters:
      - $ref: '#/components/parameters/WebId'
      - name: startTime
        in: query
        schema:
          type: string
          default: '*-1d'
      - name: endTime
        in: query
        schema:
          type: string
          default: '*'
      - name: interval
        in: query
        description: Interval between values (e.g. "1h", "5m")
        schema:
          type: string
          default: 1h
      - name: desiredUnits
        in: query
        schema:
          type: string
      - name: maxCount
        in: query
        schema:
          type: integer
          default: 1000
      - name: selectedFields
        in: query
        schema:
          type: string
      responses:
        '200':
          description: Interpolated values
          content:
            application/json:
              schema:
                type: object
                properties:
                  Items:
                    type: array
                    items:
                      $ref: '#/components/schemas/TimedValue'
  /streams/{webId}/summary:
    get:
      operationId: getStreamSummary
      summary: Get stream summary statistics
      description: Returns statistical summaries (min, max, average, count, etc.) for a stream over a time range.
      tags:
      - Streams
      parameters:
      - $ref: '#/components/parameters/WebId'
      - name: startTime
        in: query
        schema:
          type: string
          default: '*-1d'
      - name: endTime
        in: query
        schema:
          type: string
          default: '*'
      - name: summaryType
        in: query
        description: Comma-separated summary types
        schema:
          type: string
          example: Minimum,Maximum,Average,StdDev,Count
      - name: calculationBasis
        in: query
        schema:
          type: string
          enum:
          - TimeWeighted
          - EventWeighted
          default: TimeWeighted
      responses:
        '200':
          description: Summary statistics
          content:
            application/json:
              schema:
                type: object
                properties:
                  Items:
                    type: array
                    items:
                      $ref: '#/components/schemas/StreamSummary'
components:
  schemas:
    Error:
      type: object
      properties:
        Errors:
          type: array
          items:
            type: string
    StreamSummary:
      type: object
      properties:
        Type:
          type: string
          enum:
          - Minimum
          - Maximum
          - Average
          - StdDev
          - Total
          - Count
          - Range
          - PercentGood
        Value:
          $ref: '#/components/schemas/TimedValue'
    PaginationLinks:
      type: object
      properties:
        First:
          type: string
          format: uri
        Previous:
          type: string
          format: uri
          nullable: true
        Next:
          type: string
          format: uri
          nullable: true
        Last:
          type: string
          format: uri
    TimedValue:
      type: object
      description: A PI time-series value with timestamp
      properties:
        Timestamp:
          type: string
          format: date-time
        Value:
          description: Value; numeric, string, or digital state object
          oneOf:
          - type: number
          - type: string
          - type: object
            properties:
              Name:
                type: string
              Value:
                type: integer
        Good:
          type: boolean
          description: True if value is of good quality
        Questionable:
          type: boolean
        Substituted:
          type: boolean
        Annotated:
          type: boolean
        UnitsAbbreviation:
          type: string
  responses:
    NotFound:
      description: Resource not found
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  parameters:
    WebId:
      name: webId
      in: path
      required: true
      description: PI Web API WebId (unique opaque identifier for PI System objects)
      schema:
        type: string
  securitySchemes:
    basicAuth:
      type: http
      scheme: basic
      description: HTTP Basic Authentication
    kerberos:
      type: http
      scheme: negotiate
      description: Kerberos/Windows Integrated Authentication