Interaction receiver

Limit order protocol has the ability to call an intermediate contract when an order is filled.

Intermediate contract should implement an interface: InteractiveNotificationReceiver.sol

Use case

For example, we want to create a limit order 1INCH - WETH, but so that when this order is filled, we will not receive WETH but ETH.

To do this, let's create a smart contract:

contract WethUnwrapper is InteractiveNotificationReceiver {
    // solhint-disable-next-line no-empty-blocks
    receive() external payable {}

    function notifyFillOrder(
        address /* taker */,
        address /* makerAsset */,
        address takerAsset,
        uint256 /* makingAmount */,
        uint256 takingAmount,
        bytes calldata interactiveData
    ) external override {
        address payable makerAddress;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            makerAddress := shr(96, calldataload(interactiveData.offset))
        }
        IWithdrawable(takerAsset).withdraw(takingAmount);
        makerAddress.transfer(takingAmount);
    }
}

And create a limit order with preInteraction and/or postInteraction field:

const interactiveReceiverAddress = '0x1282d0c06368c40c8d4a4d818d78f258d982437b';
const walletAddress = '0xfb3c7ebccccAA12B5A884d612393969Adddddddd';

const limitOrder = limitOrderBuilder.buildLimitOrder({
    makerAssetAddress: '0xbb4cdb9cbd36b01bd1cbaebf2de08d9173bc095c',
    takerAssetAddress: '0x111111111117dc0aa78b770fa6a738034120c302',
    makerAddress: walletAddress,
    reciever: interactiveReceiverAddress,
    makerAmount: '100',
    takerAmount: '200',

    // What to do before the transfer
    preInteraction: '0x',
    // What tot do after the trasnfer has been made
    postInteraction: interactiveReceiverAddress + walletAddress.slice(2),
});

As you can see, the postInteraction field consists of two parts - the contract address and the interactiveData (which contains the wallet address).

We also set the interactiveReceiverAddress as the reciever. This is necessary in order for this contract to receive a WETH when filling out an limit order and return ETH to the creator of the limit order.

Now the limit order will work according to the following scenario:

• someone (taker) will create a transaction to execute a limit order
• taker funds (WETH) will be transferred to the interactiveReceiver contract
• interactiveReceiver contract will send the same amount of ETH to the maker
• and finally, the maker asset (1INCH) will be transferred from the maker's address to the taker's address

Example of transaction

However, this is one example of the use of interactivity. You can implement any other scenario