# SPDX-FileCopyrightText: 2024 Weidmueller Interface GmbH & Co. KG <oss@weidmueller.com>
#
# SPDX-License-Identifier: MIT

asyncapi: 2.6.0
id: https://127.0.0.1:49360
info:
  title: u-os-hub-api
  version: 1.0.1
  # TODO: Replace <ADD_DOCS_URL_HERE> in the description with the URL
  description:
    This document describes all endpoints and payloads of the Variable-NATS-API in the u-OS Data Hub.
    The endpoints refer to NATS subjects and the payloads are encoded as FlatBuffers binary blobs.
    For this specification, the FlatBuffers were converted into json schemas via ‘flatc --jsonschema’.

    Please read the u-OS Data Hub documentation <ADD_DOCS_URL_HERE> that describes when to use which endpoint for what purpose.
  contact:
    name: Weidmüller Interface GmbH & Co. KG
    url: https://www.weidmueller.com
    email: info@weidmueller.com
  license:
    name: MIT
servers:
  device:
    url: 127.0.0.1:49360
    protocol: NATS
defaultContentType: application/x-flatbuffers
channels:
  v1.loc.{providerId}.vars.evt.changed:
    description: An event from a provider to the consumers.
      This event describes a provider's list of variables that have changed their value or quality.
    parameters:
      providerId:
        $ref: "#/components/parameters/ProviderName"
    publish:
      description: A provider publishes its list of variables, if they have changed their value or quality.
      operationId: emitVariablesChangedEvent
      tags:
        - name: provider
      message:
        $ref: "#/components/messages/VariablesChangedEvent"
    subscribe:
      description:
        A consumer subscribes to this subject to be informed about variable value changes.
        The consumer receives an event with a list of all variables whose value or quality has changed.
        The consumer must filter out the variable ID(s) of interest from that list.

      operationId: receiveVariablesChangedEvent
      tags:
        - name: consumer
      message:
        $ref: "#/components/messages/VariablesChangedEvent"
  v1.loc.{providerId}.vars.qry.read:
    description:
      A consumer sends a query to this subject to read all variables from the provider.

      NATS automatically adds a response subject to the request which the provider uses for the response.
    parameters:
      providerId:
        $ref: "#/components/parameters/ProviderName"
    publish:
      description: A consumer publishes a request for reading a list of provider variables.
      operationId: emitReadVariablesQueryRequest
      tags:
        - name: consumer
      message:
        $ref: "#/components/messages/ReadVariablesQueryRequest"
    subscribe:
      description:
        A provider subscribes to this subject in order to receive read variable queries for its variables.
        It receives Nats requests on this subject and responds via the response subject supplied in the request.

      operationId: receiveReadVariablesQueryRequest
      tags:
        - name: provider
      message:
        $ref: "#/components/messages/ReadVariablesQueryRequest"
  v1.loc.{providerId}.vars.cmd.write:
    description: A command from a consumer to a provider, writing a list of provider variables.
    parameters:
      providerId:
        $ref: "#/components/parameters/ProviderName"
    publish:
      description: A consumer publishes a command to write a list of provider variables.
      operationId: emitWriteVariablesCommand
      tags:
        - name: consumer
      message:
        $ref: "#/components/messages/WriteVariablesCommand"
    subscribe:
      description: A provider subscribes to this subject to receive write variables commands for its variables.
      operationId: receiveWriteVariablesCommand
      tags:
        - name: provider
      message:
        $ref: "#/components/messages/WriteVariablesCommand"
  v1.loc.{providerId}.def.evt.changed:
    description: An event from a provider to the registry indicating that a provider's definition has changed.
    parameters:
      providerId:
        $ref: "#/components/parameters/ProviderName"
    publish:
      description: A provider publishes the changed provider definition.
      operationId: emitProviderDefinitionChangedEvent
      tags:
        - name: provider
      message:
        $ref: "#/components/messages/ProviderDefinitionChangedEvent"
  v1.loc.registry.providers.{providerId}.def.qry.read:
    description: A query from a consumer to the registry requesting a provider's definition.
    parameters:
      providerId:
        $ref: "#/components/parameters/ProviderName"
    publish:
      description: A consumer queries a provider's definition.
      operationId: emitReadProviderDefinitionQueryRequest
      tags:
        - name: consumer
      message:
        $ref: "#/components/messages/ReadProviderDefinitionQueryRequest"
  v1.loc.registry.providers.{providerId}.def.evt.changed:
    description:
      Clients can subscribe to events indicating that the provider definition has changed.
      The registry checks the new provider definition before it sends the event and marks it as OK or INVALID.
    parameters:
      providerId:
        $ref: "#/components/parameters/ProviderName"
    subscribe:
      description:
        A client subscribes to changes of a provider definition. If a change occurs, the client receives an event with the updated provider definition.
        Consumers shall refresh the variable list.
        Both consumers and the provider evaluate the provider definition's status.
      operationId: receiveProviderDefinitionChangedEvent
      tags:
        - name: consumer
        - name: provider
      message:
        $ref: "#/components/messages/ProviderDefinitionChangedEvent"
  v1.loc.registry.providers.qry.read:
    description: A query from a consumer to the registry requesting a list of providers.
    publish:
      description: A consumer requests a list of providers.
      operationId: emitReadProvidersQueryRequest
      tags:
        - name: consumer
      message:
        $ref: "#/components/messages/ReadProvidersQueryRequest"
  v1.loc.registry.providers.evt.changed:
    description:
      An event from the registry which contains a list of available providers.
      The event is only triggered if a provider is removed (disconnect or deregistration) or a new one is added.
      Providers with INVALID definitions also appear in the list.
    subscribe:
      description: A consumer subscribes to this subject to get notified about available providers in the system.
      operationId: receiveProvidersChangedEvent
      tags:
        - name: consumer
      message:
        $ref: "#/components/messages/ProvidersChangedEvent"
  v1.loc.registry.state.evt.changed:
    description: This event indicates that the state of the registry has changed.
    subscribe:
      description:
        A client that has subscribed to this event receives a message when the state of the registry has changed.
        If a provider receives a 'registry up' event via this subject, it shall resend its provider definition.
      operationId: receiveStateChangedEvent
      tags:
        - name: consumer
        - name: provider
      message:
        $ref: "#/components/messages/StateChangedEvent"
  _INBOX.{consumerName}.{sessionId}:
    description: The inbox subject for all queries.
      The NATS broker automatically forwards responses to the NATS requests via this subject.
      It is important that the property 'custom_inbox_prefix' is set to '_INBOX.{CLIENT_NAME}' when setting up the NATS connection so that NATS can generate the subject correctly.
    parameters:
      consumerName:
        $ref: "#/components/parameters/ConsumerName"
      sessionId:
        $ref: "#/components/parameters/SessionId"
    publish:
      description: A client publishes the response to a query on this subject.
        The exact subject for the query is encoded in the request.
        If the client uses the NATS respond function, NATS automatically uses the correct subject.
      operationId: replyFromConsumer
      tags:
        - name: provider
      message:
        oneOf:
          - $ref: "#/components/messages/ReadProviderDefinitionQueryResponse"
          - $ref: "#/components/messages/ReadProvidersQueryResponse"
          - $ref: "#/components/messages/ReadVariablesQueryResponse"
    subscribe:
      description:
        A client subscribes to this subject in order to receive the response to its queries.
        If the client uses the NATS request function, NATS takes care of subscribing to the correct subject.
      operationId: replyFromProvider
      tags:
        - name: consumer
components:
  messages:
    ProviderDefinitionChangedEvent:
      #      messageId: ProviderDefinitionChangedEvent
      payload:
        $ref: "jsonschemas/messages/provider_definition_changed_event.schema.json"
    ProvidersChangedEvent:
      messageId: ProvidersChangedEvent
      payload:
        $ref: "jsonschemas/messages/providers_changed_event.schema.json"
    ReadProviderDefinitionQueryRequest:
      messageId: ReadProviderDefinitionQueryRequest
      headers:
        $ref: "#/components/schemas/Headers"
      correlationId:
        $ref: "#/components/correlationIds/Reply"
      payload:
        $ref: "jsonschemas/messages/read_provider_definition_query_request.schema.json"
    ReadProviderDefinitionQueryResponse:
      messageId: ReadProviderDefinitionQueryResponse
      headers:
        $ref: "#/components/schemas/ResponseHeaders"
      payload:
        $ref: "jsonschemas/messages/read_provider_definition_query_response.schema.json"
    ReadProvidersQueryRequest:
      messageId: ReadProvidersQueryRequest
      headers:
        $ref: "#/components/schemas/Headers"
      correlationId:
        $ref: "#/components/correlationIds/Reply"
      payload:
        $ref: "jsonschemas/messages/read_providers_query_request.schema.json"
    ReadProvidersQueryResponse:
      messageId: ReadProvidersQueryResponse
      headers:
        $ref: "#/components/schemas/ResponseHeaders"
      payload:
        $ref: "jsonschemas/messages/read_providers_query_response.schema.json"
    ReadVariablesQueryRequest:
      headers:
        $ref: "#/components/schemas/Headers"
      correlationId:
        $ref: "#/components/correlationIds/Reply"
      payload:
        $ref: "jsonschemas/messages/read_variables_query_request.schema.json"
    ReadVariablesQueryResponse:
      headers:
        $ref: "#/components/schemas/ResponseHeaders"
      payload:
        $ref: "jsonschemas/messages/read_variables_query_response.schema.json"
    StateChangedEvent:
      messageId: StateChangedEvent
      payload:
        $ref: "jsonschemas/messages/state_changed_event.schema.json"
    VariablesChangedEvent:
      payload:
        $ref: "jsonschemas/messages/variables_changed_event.schema.json"
    WriteVariablesCommand:
      payload:
        $ref: "jsonschemas/messages/write_variables_command.schema.json"
  parameters:
    ConsumerName:
      description: Name of the consumer.
      schema:
        type: string
    ProviderName:
      description: Name of the provider.
      schema:
        type: string
    SessionId:
      description: Id of the request-reply session.
      schema:
        type: string
  correlationIds:
    Reply:
      description: Correlation reply channel.
      location: $message.header#/reply
  schemas:
    Duration:
      $ref: "jsonschemas/messages/variables_changed_event.schema.json#/definitions/weidmueller_ucontrol_hub_Duration"
    Headers:
      type: object
      properties:
        reply:
          description: Reply channel set by application
          type: string
    ProviderDefinition:
      $ref: "jsonschemas/messages/provider_definition_changed_event.schema.json#/definitions/weidmueller_ucontrol_hub_ProviderDefinition"
    ProviderList:
      $ref: "jsonschemas/messages/providers_changed_event.schema.json#/definitions/weidmueller_ucontrol_hub_ProviderList"
    ResponseHeaders:
      type: object
      properties:
        reply:
          description: Reply channel set by application
          type: string
        status:
          description: Status code like defined in [RFC7231](https://datatracker.ietf.org/doc/html/rfc7231#section-6)
          type: integer
    State:
      $ref: "jsonschemas/messages/state_changed_event.schema.json#/definitions/weidmueller_ucontrol_hub_State"
    Timestamp:
      $ref: "jsonschemas/messages/variables_changed_event.schema.json#/definitions/weidmueller_ucontrol_hub_Timestamp"
    VariableList:
      $ref: "jsonschemas/messages/variables_changed_event.schema.json#/definitions/weidmueller_ucontrol_hub_VariableList"
tags:
  - name: consumer
    description: Consumer
  - name: provider
    description: Provider