BSL API

BSL is the Business Line interface for latency-sensitive order entry. It is the client contract for professional quoting, cancel/replace, execution replay, and session controls. The older market-maker and binary names remain as compatibility routes, but new integrations should use BSL names and headers.

BSL is not a separate matching engine. Orders still pass through the same auth, risk, sequencing, WAL, matching, event ring, and recovery model as the rest of the venue. The difference is that the interface exposes that hotpath truth directly instead of hiding it behind read-plane polling.

Access and Keys

BSL does not rely on one freely shared global key. Base order submit is open to any funded account that sends a valid wallet-signed action; in the current beta the X-Senticore-Order-Entry-Key header is optional for signed submit routes. This keeps market makers from being blocked by a per-request gateway credential when the order itself already carries the account signature.

Provisioned BSL credentials still matter. Higher limits, persistent sessions, private reads, execution gap-fill, receipts, cancel-on-disconnect controls, FIX Logon, and drop-copy use account-scoped API Agent credentials. Create them through the wallet-authorized API Agents flow or via institutional onboarding. Do not embed owner wallet keys or admin credentials in trading systems.

Practical rule:

Flow	Credential requirement
Signed BSL order submit	Valid signed action; optional X-Senticore-Order-Entry-Key when operations assigns a dedicated lane key.
BSL private execution stream and gap-fill	Account/agent credential or private session token.
Receipts, session controls, limits, quote obligations	Provisioned BSL/API Agent credential with the required scope.
FIX order entry and drop-copy	HMAC API Agent credential in FIX Logon.

Who should use BSL

Use BSL when late information is more dangerous than a fast reject:

Client profile	Recommended BSL posture
Market maker / liquidity provider	Persistent session, market-shard aware routing, ack for quote refresh, private execution stream as truth.
HFT / latency-sensitive taker	full for IOC/FOK and cancel/replace, strict clientOrderId, reject-code driven retry policy.
Institutional OMS	FIX where required, BSL for lower-overhead batch or compact submission, private stream/gap-fill for reconciliation.
Retail or web app backend	Prefer Trading HTTP and normal private WebSocket unless you need BSL result modes.

For HFT and market makers, the rule is simple: do not poll private reads to discover whether the engine already acted. Submit with the right BSL result mode, consume the execution stream, and gap-fill only after reconnect.

Core Endpoints

Endpoint	Purpose
POST /api/v1/bsl/orders/batch	JSON signed action batch with explicit result mode
POST /api/v1/bsl/orders/compact	Compact byte batch for latency-sensitive clients
POST /api/v1/bsl/orders/replace	Atomic cancel/new replace facade
POST /api/v1/bsl/orders/cancel-replace	Alias for replace-style order flow
GET /api/v1/bsl/receipts	Receipt and acknowledgement replay
GET /api/v1/bsl/limits	Current BSL rate, batch, backlog, and lane limits
GET /api/v1/bsl/sessions	Authenticated BSL session state
POST /api/v1/bsl/sessions/cancel-on-disconnect	Stale-order cleanup trigger
GET /api/v1/bsl/markets/{marketId}/quote-obligations	Two-sided quote obligation state
GET /api/v1/bsl/executions	Execution stream contract metadata
GET /api/v1/bsl/accounts/{account}/executions?fromSeq=...	Private execution gap-fill
GET /api/v1/ws/bsl/{account}	Private execution stream over WebSocket

Result Modes

BSL result mode is selected with x-bsl-result-mode or the JSON resultMode field.

Mode	Meaning	Use
ack	Sequencer accepted the request boundary.	Quote refreshes where stream reconciliation is primary.
durable	WAL/durable LSN boundary reached.	Slower control flows where persistence acknowledgement matters.
full	Engine-applied result returned from the hotpath.	IOC/FOK, cancel, replace, and any flow where the client needs the terminal result immediately.

full responses include actionResults when the request reaches the engine. Each result includes the client order id, order id, status, filled quantity, leaves quantity, average price, fee, reject code, market, shard, seq, and engine timestamps when available.

Response Contract

Every BSL JSON response carries a bsl object:

{
  "bsl": {
    "contract": "BSL_ORDER_ENTRY_V1",
    "contractVersion": 1,
    "surface": "orderEntry",
    "transport": "json",
    "requestedResultMode": "full",
    "resultMode": "full",
    "streamTruth": "engine_execution_ring",
    "privateWsPath": "/api/v1/ws/bsl/{account}",
    "executionReplayPath": "/api/v1/bsl/accounts/{account}/executions?fromSeq={seq}",
    "rejectCode": null,
    "timing": {
      "gatewayReceivedTs": 1781715570085,
      "authDoneTs": 1781715570085,
      "riskDoneTs": 1781715570085,
      "sequencedTs": 1781715570085,
      "engineAppliedTs": 1781715570086,
      "durableTs": null,
      "responseSentTs": 1781715570086,
      "durationsUs": {
        "total": 1072,
        "auth": 3,
        "routing": 12,
        "risk": 0,
        "enqueue": 0,
        "ackResolution": 0,
        "responseEmit": 58
      }
    }
  }
}

Compact byte responses expose the same contract through x-bsl-* headers.

Fast Rejects

BSL clients should treat fast rejection as healthy backpressure. A quick reject is better than letting a quote age silently in an overloaded queue.

Stable BSL reject codes include:

Code	Meaning
SHARD_BUSY	The target market shard is overloaded.
QUEUE_LIMIT	The BSL lane or ingress queue is full.
RISK_CREDIT_LIMIT	Risk or credit policy blocked the action.
KILL_SWITCH	Account, market, or venue kill-switch is active.
MARKET_HALTED	Market state does not allow the requested action.
AUTH_REQUIRED	Missing or invalid credentials on a protected BSL route; signed submit can run without a lane key when beta policy allows it.
PERMISSION_DENIED	Credential lacks the requested scope.
DUPLICATE_OR_STALE	Nonce, idempotency, or duplicate replay state rejected the request.
INVALID_REQUEST	Frame, schema, or request payload is invalid.

Related Pages

• Order Entry
• Execution Streams
• Operations