Topic
How automated orders actually reach the market: authorisation, idempotency, reconciliation and the permissions never to grant.
3 pieces published on this topic · Updated
A broker API is the mechanism by which an automated strategy places a real order. The authorisation model is the part worth understanding first: a client grants a platform permission to submit orders against their own brokerage account, and the account, the funds and the holdings stay with the broker. A platform that asks for a transfer of funds is describing something else entirely.
The engineering problem the APIs create is that order submission is a network call, and network calls fail in ways that leave the outcome unknown. A request can be accepted by the broker and the response lost, so a naive retry becomes a second position, and the system's own records will show only one. The standard defence is an idempotency key generated before the first attempt and reused on every retry.
Everything else follows from not trusting your own bookkeeping. Session tokens expire, often daily, and expiry should be detected before a trading session rather than discovered by a failing order. Positions should be reconciled against the broker's own view rather than derived from a ledger of responses. And rate limits should be treated as a design constraint, not an error to handle.
Engineering deep-dives covering this topic.
Who registers the algorithm, whose static IP it is, and who carries the liability, answered from the circulars, with every reference attached.
The retention obligation, the fields an inspection actually asks for, and why "comprehensive logging" is not an answer to the question.
How authorised API access works under the framework, and why the once-per-calendar-week limit on changing an IP breaks naive failover designs.
Describe a strategy in plain language, backtest it against historical data, and paper trade it before any capital is committed.
