OrderBookDeltas

OrderBookDeltas groups a non-empty batch of OrderBookDelta records from one logical book event. It reduces per-message overhead when an adapter receives or produces several changes at once.

Fields

Field	Rust type	Python type	Required/default	Notes
instrument_id	InstrumentId	InstrumentId	Required	Instrument whose book is changing.
deltas	Vec<OrderBookDelta>	list[OrderBookDelta]	Required	Non-empty batch of deltas.
flags	u8	int	From last delta	Last delta flags.
sequence	u64	int	From last delta	Last delta sequence number.
ts_event	UnixNanos	int	From last delta	Last delta event timestamp.
ts_init	UnixNanos	int	From last delta	Last delta initialization timestamp.

Behavior

• The batch must contain at least one delta.
• Every delta's instrument_id must match the batch instrument_id.
• The batch metadata mirrors the final delta.
• The final delta should carry F_LAST when it closes a logical event group. See Delta flags and event boundaries.
• Snapshot batches usually begin with a CLEAR delta and end with F_SNAPSHOT | F_LAST.

Example

use nautilus_core::UnixNanos;
use nautilus_model::{
    data::{BookOrder, OrderBookDelta, OrderBookDeltas},
    enums::{BookAction, OrderSide, RecordFlag},
    identifiers::InstrumentId,
    types::{Price, Quantity},
};

let instrument_id = InstrumentId::from("ETHUSDT-PERP.BINANCE");
let bid = OrderBookDelta::new(
    instrument_id,
    BookAction::Add,
    BookOrder::new(OrderSide::Buy, Price::from("2500.10"), Quantity::from("3.5"), 1),
    0,
    41,
    UnixNanos::from(1_000_000_000),
    UnixNanos::from(1_000_000_100),
);
let ask = OrderBookDelta::new(
    instrument_id,
    BookAction::Add,
    BookOrder::new(OrderSide::Sell, Price::from("2500.20"), Quantity::from("2.0"), 2),
    RecordFlag::F_LAST as u8,
    42,
    UnixNanos::from(1_000_000_000),
    UnixNanos::from(1_000_000_100),
);

let deltas = OrderBookDeltas::new(instrument_id, vec![bid, ask]);

from nautilus_trader.model import InstrumentId
from nautilus_trader.model import Price
from nautilus_trader.model import Quantity
from nautilus_trader.model import BookAction
from nautilus_trader.model import BookOrder
from nautilus_trader.model import OrderBookDelta
from nautilus_trader.model import OrderBookDeltas
from nautilus_trader.model import OrderSide
from nautilus_trader.model import RecordFlag

instrument_id = InstrumentId.from_str("ETHUSDT-PERP.BINANCE")
bid = OrderBookDelta(
    instrument_id=instrument_id,
    action=BookAction.ADD,
    order=BookOrder(
        OrderSide.BUY,
        Price.from_str("2500.10"),
        Quantity.from_str("3.5"),
        1,
    ),
    flags=0,
    sequence=41,
    ts_event=1_000_000_000,
    ts_init=1_000_000_100,
)
ask = OrderBookDelta(
    instrument_id=instrument_id,
    action=BookAction.ADD,
    order=BookOrder(
        OrderSide.SELL,
        Price.from_str("2500.20"),
        Quantity.from_str("2.0"),
        2,
    ),
    flags=RecordFlag.F_LAST,
    sequence=42,
    ts_event=1_000_000_000,
    ts_init=1_000_000_100,
)

deltas = OrderBookDeltas(instrument_id, [bid, ask])

Related guides

• OrderBookDelta covers the contained update type.
• Order books explains supported order book state.
• Python API reference lists Python members.