Stream fills

Fill frames for the caller’s own executions.

SEND/ws

Authorization

UDX-Access-KeyAPI key · headerrequired

Opaque API key ID.

UDX-Access-TimestampAPI key · headerrequired

Unix time in milliseconds, within 30 seconds of server time.

UDX-Access-SignatureAPI key · headerrequired

Standard-base64 RSA-PSS/SHA-256 signature with a 32-byte salt. Sign timestamp + "GET" + "/ws"; the upgrade request has no body hash and no idempotency key.

Messages

fillDeliver one execution of one of the caller's orders.

typestringrequired

Identifies one fill.

sidSubscriptionIdrequired

Exchange-assigned subscription ID whose lifetime is this WebSocket connection.

min 1 · max 9007199254740991

seqSequenceNumberrequired

Gap-detection sequence local to one subscription. It starts at 1 and increments once per frame on that subscription.

min 1 · max 9007199254740991

msgFillrequired

An execution of one of the caller's own orders.

Show properties

trade_idstringrequired

Exchange-assigned trade identifier.

max length 64

order_idEntityIdrequired

An exchange-assigned identifier. Treat it as an opaque, stable key with no internal structure.

min length 1

client_order_idClientId

A client-supplied correlation identifier.

account_idstringrequired

The account the filled order was placed under.

min length 1

tickerTickerrequired

A human-meaningful natural key naming a single-leg or multi-leg market.

min length 1 · max length 128

sideOrderSiderequired

Order side.

Allowed:buysell

pricestringrequired

Fill price, in YES dollars.

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

quantitystringrequired

Contracts filled.

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

feestringrequired

Fee collected for this execution.

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

is_takerbooleanrequired

Whether the caller's order was the aggressor (taker) of the trade.

executed_atstring<date-time>required

When this fill's execution occurred.

max length 40

Errors

channel_unavailableThe channel's upstream source cannot serve the operation right now. Retry with backoff; the connection stays usable.

codestringrequired

Stable machine-readable error code.

detailErrorDetailrequired

Human-readable occurrence detail that clients must not parse.

min length 1 · max length 500

instanceErrorInstancerequired

Request identifier for troubleshooting with exchange 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}$

internal_errorAn unexpected failure left connection state safe to continue.

codestringrequired

Stable machine-readable error code.

detailErrorDetailrequired

Human-readable occurrence detail that clients must not parse.

min length 1 · max length 500

instanceErrorInstancerequired

Request identifier for troubleshooting with exchange 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, within 30 seconds of server time.

max length 13 · matches ^[0-9]{13}$

UDX-Access-Signaturestringrequired

Standard-base64 RSA-PSS/SHA-256 signature with a 32-byte salt. Sign timestamp + "GET" + "/ws"; the upgrade request has no body hash and no idempotency key.

min length 1 · max length 1024

Sec-WebSocket-Protocolstringrequired

Negotiated dated WebSocket API version.

Examples

fill

{
  "type": "fill",
  "sid": 14,
  "seq": 1,
  "msg": {
    "trade_id": "TRD-EXAMPLE-1",
    "order_id": "ORD-EXAMPLE-1",
    "client_order_id": "my-order-1",
    "account_id": "ACC-EXAMPLE-1",
    "ticker": "UDX-EXAMPLE-MARKET-A",
    "side": "buy",
    "price": "0.55",
    "quantity": "100",
    "fee": "0.02",
    "is_taker": true,
    "executed_at": "2026-01-01T00:00:00.000000Z"
  }
}

channel_unavailable

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

internal_error

{
  "type": "error",
  "sid": 7,
  "msg": {
    "code": "internal_error",
    "detail": "the subscription could not be continued",
    "instance": "urn:request-id:4ecbe594-50fa-4b7a-950f-5ed74bb8372d"
  }
}