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GuideHow Does It Work?

RainLink Workflow

Cross-chain bridge technology enables asset transfers between different blockchains. Below is an in-depth look at its core components and workflow.

Key Components

A cross-chain bridge consists of three main parts:

Custodian

  • Locks the user’s deposited assets.
  • Deployed on the source chain (e.g., Ethereum) via a smart contract.

Debt Issuer

  • Mints corresponding tokens on the target chain.
  • Implemented on the target chain as a smart contract.

Communicator

  • Relays messages between chains.
  • Runs off-chain, continuously monitoring source-chain events and forwarding them to the target chain.

Workflow

Incoming Flow

  1. The user invokes a contract call to deposit ETH into the custodian on Ethereum.
  2. The custodian smart contract emits an event confirming receipt.
  3. The communicator detects this event and sends a signal to the debt issuer on the target chain.
  4. The debt issuer mints the wrapped token (acETH) and transfers it to the user’s address, completing the cross-chain transfer.

To reverse the process:

Outgoing Flow

  1. The user burns acETH via the debt issuer on the target chain.
  2. Once the burn is confirmed, the debt issuer emits a redemption event.
  3. The communicator picks up this event and notifies the custodian on the source chain.
  4. The custodian releases the original ETH back to the user’s address.

Fees & Security Checks

When bridging assets, two factors are crucial: fees and validity verification.

Fees

Users typically pay:

BridgeFee=TransactionFee+ServiceFeeBridge Fee = Transaction Fee + Service Fee
  1. Transaction Fee: Gas costs on the source and/or target blockchain (e.g., Ethereum gas).

  2. Service Fee: Charged by the bridge provider. See Bridge Fee Schedule for details.

Validity Verification

The communicator ensures security by:

  1. Executing the lock or burn on the source chain.

  2. Waiting for a sufficient number of confirmations to guarantee finality.

  3. Relaying the event only after confirmation, ensuring the cross-chain transfer is both safe and valid.

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