Across

Takers based on Across protocol. Two primary flows are supported:

• fill - take pool asset for filling an already deposited order on another chain in exchange for repayment to the origin's pool of the same enclave

• deposit - take pool asset and immediately deposit it expecting the order to be filled on another chain with the same enclave's pool as recipient

Across Fill

AcrossFillTaker implementation of taker provides an ability to take pool asset for filling an already deposited order on another chain in exchange for repayment to the origin's pool of the same enclave. The taker contract expects input and output tokens to match tokens managed by pools in corresponding chains.

First, Across deposit must be committed on the origin chain. This action emits FundsDeposited event, the proof of which is expected on the take chain (depositProof). Along with the proof, the takeToFillRelay function accepts a number of parameters to reconstruct the original event for verification.

Number of assets for take is allowed to be different from outputAssets due to rebalance logic and strict validation of the original event components. The take sufficiency will be validated still and any surplus assets of the operation will be returned to the taker caller.

Once event and parameters are verified, SpokePool's fillRelay function is called. The taker contract provides the asset for the fill as msg.sender, specifying the repayment chain to be the origin giveChain chain and the receiver account to be givePool, thus ensuring givePoolAsset token will be returned to the enclave eventually.

If any of take, verification, or fillRelay phases fails, entire takeToFillRelay call fails.

Across Deposit

AcrossDepositTaker implementation of taker provides an ability to take pool asset and immediately deposit it expecting the order to be filled on another chain with the same enclave's pool as recipient. The order created has input and output tokens matching the tokens managed by the pools in corresponding chains.

As the first step, a solver should call takeToDeposit function of the taker. The taker will receive at least assets from the pool, which is with the optional surplus should be sufficient to cover inputAmount (the rest is returned to the caller). The outputAmount value should cover pool-requested minGiveAssets.

Once deposit is successfully created, the solver should obtain FundsDeposited event details and fill the order on the target chain (giveChain) using SpokePool's fillRelay function. If this part is failed (deadline exceeded), funds are returned to the pool on the origin chain by Across protocol - as specified in the on-chain formed order.