Bloomberg Applications Blpapi Events

generated: '2026-08-27'
method: searched
source: >-
  https://data.bloomberglp.com/professional/sites/10/2017/03/BLPAPI-Core-Developer-Guide.pdf
  (section 10, "Event Types", and section 9.2, "Message Return Codes")
provider: Bloomberg Applications
providerId: bloomberg-applications
description: >-
  Bloomberg ships a genuine push/streaming event surface and publishes no AsyncAPI document for it.
  This file captures the real event catalog from Bloomberg's own developer guide so the surface is
  recorded rather than lost. It is deliberately NOT an AsyncAPI document and carries no AsyncAPI or
  Webhooks pointer: Bloomberg publishes no AsyncAPI, and there are no webhooks here — no callback
  URL is ever registered, because delivery is a persistent subscription over the BLPAPI wire
  protocol, not an HTTP POST to a consumer endpoint.
surface_type: subscription streaming (binary protocol, not HTTP callbacks)
asyncapi_published: false
webhooks_published: false
transport:
  protocol: BLPAPI v3 binary wire protocol
  delivery: >-
    Asynchronous event queue. Data and status messages interleave on the same queue and are
    demultiplexed by client-assigned correlation IDs.
  services:
    - name: //blp/mktdata
      description: Streaming market data subscriptions.
    - name: //blp/mktvwap
      description: Streaming VWAP subscriptions.
    - name: //blp/refdata
      description: Request/response reference, historical, intraday bar and intraday tick data.
    - name: //blp/apiauth
      description: Authorization and entitlement state (Server API and B-PIPE).
event_types:
  - name: SESSION_STATUS
    description: Changes in the state of the session — started, terminated, connection up or down.
    messages:
      - SessionStarted
      - SessionTerminated
      - SessionStartupFailure
      - SessionConnectionUp
      - SessionConnectionDown
      - SessionClusterInfo
      - SessionClusterUpdate
  - name: SERVICE_STATUS
    description: Changes to the status of an active open service request.
    messages:
      - ServiceOpened
      - ServiceOpenFailure
  - name: SUBSCRIPTION_DATA
    description: Streaming subscription data delivered for active subscription requests.
    messages:
      - MarketDataEvents
  - name: SUBSCRIPTION_STATUS
    description: Changes in the state of a pending or active subscription request.
    messages:
      - SubscriptionStarted
      - SubscriptionStreamsActivated
      - SubscriptionStreamsDeactivated
      - SubscriptionTerminated
  - name: PARTIAL_RESPONSE
    description: >-
      A non-final chunk of a non-subscription response. Bloomberg splits oversized responses into
      a sequence of these.
  - name: RESPONSE
    description: >-
      The final message of a non-subscription response. A consumer must keep reading until this
      arrives; stopping earlier truncates the result silently.
  - name: REQUEST_STATUS
    description: Changes in the state of a pending non-subscription request, including request timeout.
    messages:
      - RequestFailure
  - name: AUTHORIZATION_STATUS
    description: >-
      Changes to the state of an active authorization, including entitlement changes made in EMRS
      and mid-session revocation.
    messages:
      - AuthorizationSuccess
      - AuthorizationFailure
      - AuthorizationRevoked
      - EntitlementChanged
  - name: ADMIN
    description: Administrative events from Bloomberg services, including flow control.
    messages:
      - SlowConsumerWarning
      - SlowConsumerWarningCleared
      - DataLoss
      - RequestTemplateAvailable
      - RequestTemplatePending
      - RequestTemplateTerminated
flow_control:
  note: >-
    The backpressure contract is explicit and unusual enough to be worth stating: a slow consumer
    receives SlowConsumerWarning, and if it does not drain the queue the server emits DataLoss
    messages and drops events. DataLoss is appended at the queue position where the drop happened,
    so it can be dequeued after a SlowConsumerWarningCleared that was generated later in real time.
    A single DataLoss message may stand for a large number of lost events.
subscription_semantics:
  initial_paint: >-
    On subscribe, the API first delivers a summary of the security's current state, then streams
    updates until the subscription is cancelled. If the initial paint fails, a SubscriptionTerminated
    with an UNCLASSIFIED category is delivered and ticks still flow.
  cancellation: Session.Unsubscribe() / Cancel(); terminates the stream immediately.
  metering: >-
    Subscriptions to the same security count once regardless of differing fields, options or
    interval. See rate-limits/bloomberg-applications-rate-limits.yml.
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com