STEP 3: Post the signed order to the API

Once you have a signed order, last step is to send it to the API.

• The API will accept the order if its correctly signed, the deadline is correct, and the fee is enough to settle it

• Once accepted, the order will be OPEN until the specified validTo date (expiration)

• The possible outcomes once accepted are:

  • The order is EXECUTED: you will pay the signed fee, and get at least the buyAmount tokens you specified, although you will probably get more! (you will probably get a so-called Surplus).

  • The order EXPIRES: If your price is not good enough, and the order is out of the market price before expiration, your order will expire. This doesn't have any cost to the user, which only pays the fee if the trade is executed.

  • You cancel the order, so it becomes CANCELLED. Cancelling an order can be done both as a free meta-transaction (soft cancelations) or as a regular on-chain transaction (hard cancelations).

• The API will return an orderId which identifies the order, and is created as a summary (hash) of it. In other words, the orderId is deterministic given all the order parameters.

Post an order using the SDK:

import { OrderBookApi, SupportedChainId } from '@cowprotocol/cow-sdk'

const orderBookApi = new OrderBookApi({ chainId: SupportedChainId.MAINNET })

const orderId = await orderBookApi.sendOrder({ ...order, ...signedOrder })

Success 🎉! You managed to post a new valid order. Note that even though you awaited for the sendOrder call, this only signals that the order was accepted by the protocol. As a bonus, next section will show you how to view the estate of the order in the explorer.