---
search:
  tags:
    - Market Data
    - RECEIVE
seo:
  description: >-
    UDX validates and reserves the complete batch before assigning one
    subscription ID per… Reference for the receive operation on /ws in the
    WebSocket API API.
sidebar:
  badge: RECEIVE
  label: Subscribe to Order Book Updates
title: Subscribe to Order Book Updates
type: openapi-operation
---
UDX validates and reserves the complete batch before assigning one subscription ID per ticker. The single subscribed response contains an always-array subscriptions field and is enqueued before any sequenced data for the returned subscriptions. Each subscription becomes ready only when its own initial snapshot arrives. Retrying an exact batch on the same connection returns its existing subscription IDs without a second delivery; a partial overlap is rejected atomically.

<Operation source="websocket-api" id="receivesubscribecommand" />