Example: On-Chain Orderbook
The North Star Orderbook (live demo | source) demonstrates a fully on-chain central limit orderbook — a workload that is effectively impossible on a shared execution environment at production scale.
Why Orderbooks Need Ephemeral Rollups
Matching latency
≥400ms (slot time)
<50ms
Throughput
~65K TPS shared
>1M TPS dedicated
Account writes
30-50K writes/s for a single market
Unlimited within session
Cost at 10K orders/s
~$648/day ($236K/year)
Near-zero (session fee only)
Matching latency: <10ms order-to-fill is required for competitive market making. Shared execution means market makers face >400ms adverse selection risk per order.
Throughput: A liquid SOL/USDC market generates 5,000–50,000 order events/second (places, cancels, amendments).
State updates: Each order modification touches 3-5 accounts. At 10K orders/s, that's 30-50K account writes/s for a single market.
Cost: At 10K orders/s × $0.00075/tx = $648/day in fees. Professional market makers would pay >$200K/year in execution fees alone.
Architecture
Real-time orderbook display with 18 levels of depth on each side
500ms tick interval for price updates with Brownian motion + mean reversion
Trade history with buy/sell coloring, candlestick chart with 5-minute intervals
Wallet integration via
@solana/wallet-adapter(Phantom, OKX, wallet-standard)Sign-in-with-wallet authentication (ed25519 signature verification via
tweetnacl)
Order Types
Limit orders: placed at a specific price level, rest on the book until filled or cancelled
Market orders: execute immediately against the best available price
Order sizes follow a power-law distribution: 60% small (0.5–20 SOL), 30% medium (20–100 SOL), 10% large (100–500 SOL)
Matching Engine (on ER)
The matching engine runs as a Solana program on the Ephemeral Rollup. Orderbook state (bids, asks, user positions) is delegated to the ER at session start. Matching executes in <1ms per order. Token vaults remain on L1 — the ER reads them in readonly mode and settles via the Portal on session close.
Performance Characteristics
Order placement → fill
<50ms (vs. >400ms on shared L2)
Orderbook depth
18 levels × 2 sides = 36 price levels per tick
Tick rate
500ms (2 Hz) — scales to 100Hz+ on dedicated ER
Spread
0.01–0.08 tick size
Settlement
Batch to L1 on session close — net token transfers, not per-trade
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