About the ETH-xDai AMB
ETH-xDai Arbitrary Message Bridge information
An Arbitrary Message Bridge (AMB) between the Ethereum Mainnet and the xDai chain extends the number of the applications that can leverage cross-chain communications.
Any application can build its own AMB extension. This is represented by two mediator contracts so that either assets or arbitrary data can be transferred between chains. The deployed mediator contracts do not require a set of oracles to be setup, allowing an application to launch quickly and reducing the cost of application ownership.
The mediator contracts rely on the following information about the ETH-xDai Arbitrary Message Bridge:
Ethereum Mainnet:
AMB contract:
0x4C36d2919e407f0Cc2Ee3c993ccF8ac26d9CE64e
Gas limit to call method in the Gnosis chain:
2000000
Finalization rate:
20
blocks
Gnosis Chain:
AMB contract:
0x75Df5AF045d91108662D8080fD1FEFAd6aA0bb59
Gas limit to call method in the Ethereum Mainnet:
2000000
Finalization rate:
20
blocks
Transactions
It is possible to get an AMB transaction status by using the Live Monitoring app: http://alm-xdai.herokuapp.com/. Transactions require a multi-sig (for bridge validators, not users) for a successful transfer. Current validators can be viewed with the live monitoring application.
Fees
While there are no additional fees to bridge between GC and Ethereum, there are gas costs for transactions, which can be quite substantial depending on Ethereum gas prices. When moving from Ethereum to GC, there is a gas cost to unlock the tokens for transfer. When moving from GC to Ethereum, there is a gas cost to claim the token on Ethereum.
Additional fees may be introduced at a later time to cover expenses incurred by validators when bridging. These fees will be assessed with the transferring asset.
Withdrawal Requests
Withdrawal requests call the transfer
method of the token contracts with the mediator contract address as the recipient (the multitoken/erc20-to-erc20 extension for AMB).
A detailed description of the AMB and examples of AMB extensions are available here: Arbitrary Message Bridge (AMB).
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