> ## Documentation Index
> Fetch the complete documentation index at: https://docs.polynode.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Python — Orderbook

## Orderbook Streaming

The SDK includes a dedicated orderbook client for real-time book data from `ob.polynode.dev`. This is a separate WebSocket connection from the event stream.

### Subscribe

```python theme={null}
# Lazy-initialized, connects on first subscribe
await pn.orderbook.subscribe(["token_id_1", "token_id_2"])
```

### Event Handlers

```python theme={null}
pn.orderbook.on("snapshot", lambda snap: print(f"{snap.asset_id}: {len(snap.bids)} bids"))
pn.orderbook.on("update", lambda delta: print(f"{delta.asset_id} updated"))
pn.orderbook.on("price", lambda c: print(f"price: {c.assets[0].price}"))
pn.orderbook.on("snapshots_done", lambda msg: print(f"All {msg.total} snapshots received"))
pn.orderbook.on("*", lambda u: print(u.type))  # catch-all
```

### LocalOrderbook

Maintain a sorted local copy of the book:

```python theme={null}
from polynode import LocalOrderbook

book = LocalOrderbook()

# Wire to orderbook WS events
pn.orderbook.on("snapshot", lambda snap: book.apply_snapshot(snap))
pn.orderbook.on("update", lambda delta: book.apply_update(delta))

# Query state
full_book = book.get_book(token_id)    # (bids, asks) or None
best_bid = book.get_best_bid(token_id)  # OrderbookLevel or None
best_ask = book.get_best_ask(token_id)  # OrderbookLevel or None
spread = book.get_spread(token_id)      # float or None
```

### Cleanup

```python theme={null}
pn.orderbook.unsubscribe()    # unsubscribe from all markets
pn.orderbook.disconnect()     # close connection
```