Token Bridge Commission

This treatise explains the Heima crosschain bridge token commission fee to give our users an understanding of how it works.

Introduction

Cross-chain bridge serves as a neutral zone that enables users to deploy assets for fast and easy transactions irrespective of the blockchain network. It also reduces operational difficulties by allowing access to multiple blockchains through the same network.

Heima has developed a Crosschain Bridge that works in the same way and all its components are built in a standardized fashion to help unlock the superior liquidity in the DOTSAMA ecosystem. The crosschain bridge allows users to seamlessly send and receive HEI tokens between Polkadot (Parachain HEI) and the Ethereum network (ERC-20 HEI).

To achieve this, Heima uses a ChainBridge Relayer model that calls smart contract functions based on the transaction direction (HEI ⇌ ERC-20 HEI) and allows the Bridge Pallet to mint or burn HEI for the appropriate transaction to be carried out.

Bridge Transfer Fee Calculation(Parachain HEI → ERC20-HEI)

For every Bridge transaction that occurs within the Heima protocol, there are three ChainBridge relayers that are responsible for the approval or rejection of such transaction.

Heima Relayer Network/Address Info

We use 3 relay servers to submit and execute proposals for smart contracts and a proposal needs to get 2/3 votes to get executed. The reason for this is to prevent a single point of failure and minimize the risk of hack and malicious attacks

So basically, cross-chain transactions from parachain HEI to ERC20-HEI would result in 6 transactions on Ethereum and that's where the commission comes from. For every transaction, there are six relayer executions and at least two of the relayers must successfully execute the following two triggers (a total of 4 executions) for a transaction to be approved:

• Vote Proposal

• Execute Proposal

While the opposite is the case for failed transactions.

The remaining two triggers (to make 6 executions) are:

• Failed Vote Proposal

• Failed Execute Proposal

It is important to note that the smart contract charges different fees for each of the triggers executed by the Relayers as evident below:

Title	Cost	Execution status
Initial Gas Price on Ethereum	30 Gwei
Success VoteProposal Fee	0.001633 ETH	2 times
Failed VoteProposal Fee	0.0003472 ETH	1 times
Success ExecuteProposal Fee	0.0007872 ETH	2 times
Failed ExecuteProposal Fee	0.00035776ETH	1 times
HEI/ETH Ratio	0.000425532 HEI/ETH	HEI=$0.8, ETH=$1880
Fee based on HEI	16 HEI

The Commission Fee is calculated based on the formula below:

CommissionFee = (SucessVoteProposalFee x 2 + FailedVoteProposalFee + SucessExecuteProposalFee x 2 + FailedExecuteProposalFee)/( LIT/ETH Ratio)

The total fee charged by the smart contract for each of the Relayer triggers is then divided by the HEI/ETH ratio provided by Binance which amounts to approximately 16 HEI for Crosschain Bridge transactions.

Interestingly, based on the current ETH gas state and improved contracts, we now send 3 Transactions to transfer balance instead of 6. Thus, the token bridge commission fee is now reduced to 8 LIT.

IMPORTANT: Token Bridge Commission Fee Varies with Network Congestion Our Token Bridge commission may vary based on network congestion. We strive to keep it reasonable and transparent. You may want to plan transactions during low-activity periods for smoother transfers.