Stream Order Book Data

Each one-ticker subscription has its own gap-detecting sequence. A terminal subscription error ends only that subscription; a connection-fatal condition is reported with a WebSocket close frame. Absolute updates are idempotent and consumers deduplicate by (sid, seq); a forward gap requires the snapshot recovery procedure above.

SEND/ws

Authorization

UDX-Access-KeyAPI key · headerrequired

API key signature over `timestamp + "GET" + "/ws"`. The channel binding lists the required upgrade headers.

UDX-Access-KeyAPI key · headerrequired

API key signature over `timestamp + "GET" + "/ws"`. The channel binding lists the required upgrade headers.

Message: Order Book Snapshot

typestringrequired

Identifies a complete order book snapshot.

sidinteger<int64>required

Opaque server-assigned subscription ID whose lifetime is this WebSocket connection.

min 1 · max 9007199254740991

seqinteger<int64>required

Gap-detection sequence local to one-ticker subscription. It starts at 1 and increments once for every snapshot or update.

min 1 · max 9007199254740991

msgobjectrequired

Complete visible L2 order book state for one market.

Show properties

tickerstringrequired

A market's public ticker.

min length 1 · max length 128

bidsany[][]required

Bid levels in best-first order as `[price, quantity]` pairs.

max items 25

asksany[][]required

Ask levels in best-first order as `[price, quantity]` pairs.

max items 25

Message: Order Book Update

typestringrequired

Identifies an incremental order book update.

sidinteger<int64>required

Opaque server-assigned subscription ID whose lifetime is this WebSocket connection.

min 1 · max 9007199254740991

seqinteger<int64>required

Gap-detection sequence local to one-ticker subscription. It starts at 1 and increments once for every snapshot or update.

min 1 · max 9007199254740991

msgobjectrequired

One market's complete visible transition between book states.

Show properties

tickerstringrequired

A market's public ticker.

min length 1 · max length 128

changesobject[]required

Absolute price-level replacements applied atomically. Array order has no meaning; a zero quantity removes the level.

min items 1 · max items 100

Show properties

Array of object

sidestringrequired

`buy` is bid liquidity and `sell` is ask liquidity, both for YES.

Allowed:buysell

pricestringrequired

YES-side price in dollars as an exact fixed-point decimal string with at most six decimal places.

max length 24 · matches ^[0-9]+(\.[0-9]{1,6})?$

quantitystringrequired

Contract quantity as an exact fixed-point decimal string with at most two decimal places. Zero removes an updated price level.

max length 24 · matches ^[0-9]+(\.[0-9]{1,2})?$

Message: Subscription Error

typestringrequired

Identifies a terminal subscription failure.

sidinteger<int64>required

Opaque server-assigned subscription ID whose lifetime is this WebSocket connection.

min 1 · max 9007199254740991

msgobjectrequired

Closed set of terminal failures for an order book subscription.

Show properties

One of:

object

codestringrequired

Stable machine-readable error code.

detailstringrequired

Human-readable occurrence detail that clients must not parse.

min length 1 · max length 500

instancestring<uri-reference>required

Request ID for troubleshooting with UDX support.

max length 100 · matches ^urn:request-id:[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$

object

codestringrequired

Stable machine-readable error code.

detailstringrequired

Human-readable occurrence detail that clients must not parse.

min length 1 · max length 500

instancestring<uri-reference>required

Request ID for troubleshooting with UDX support.

max length 100 · matches ^urn:request-id:[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$

object

codestringrequired

Stable machine-readable error code.

detailstringrequired

Human-readable occurrence detail that clients must not parse.

min length 1 · max length 500

instancestring<uri-reference>required

Request ID for troubleshooting with UDX support.

max length 100 · matches ^urn:request-id:[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$

Channel bindings

ws

methodGET

headers

UDX-Access-Keystringrequired

Opaque API key ID.

min length 1 · max length 255

UDX-Access-Timestampstringrequired

Unix time in milliseconds.

max length 13 · matches ^[0-9]{13}$

UDX-Access-Signaturestringrequired

Base64 RSA-PSS/SHA-256 signature.

min length 1 · max length 1024

Sec-WebSocket-Protocolstringrequired

Negotiated dated WebSocket API version.

Example

# Prints each message as it arrives
wscat -c 'wss://api.uat.udx.underdogsports.com/ws'

const socket = new WebSocket("wss://api.uat.udx.underdogsports.com/ws");

socket.addEventListener("message", (event) => {
  console.log(JSON.parse(event.data));
});

Message

{
  "type": "orderbook_snapshot",
  "sid": 7,
  "seq": 1,
  "msg": {
    "ticker": "UDX-EXAMPLE-MARKET-A",
    "bids": [
      [
        "0.45",
        "100"
      ]
    ],
    "asks": [
      [
        "0.47",
        "80"
      ]
    ]
  }
}

{
  "type": "orderbook_update",
  "sid": 7,
  "seq": 2,
  "msg": {
    "ticker": "UDX-EXAMPLE-MARKET-A",
    "changes": [
      {
        "side": "buy",
        "price": "0.45",
        "quantity": "125"
      },
      {
        "side": "sell",
        "price": "0.47",
        "quantity": "0"
      }
    ]
  }
}

{
  "type": "subscription_error",
  "sid": 7,
  "msg": {
    "code": "market_data_unavailable",
    "detail": "Current market data is unavailable for this subscription",
    "instance": "urn:request-id:4ecbe594-50fa-4b7a-950f-5ed74bb8372d"
  }
}