Transfer tokens by using block explorers
The instructions below use the Etherscan UI and the Blockscout UI to demonstrate the token transfer process.
The process to transfer a non-fungible token from the Kovan testnet to the Sokol testnet consists of two steps:
Approve the NFT OmniBridge mediator contract on the Kovan side to operate with a non-fungible token.
Initiate a request to transfer the token through the bridge on the OmniBridge mediator contract located on Kovan.
Make sure that the token contract is verified in Etherscan. Token contracts deployed as part of the NFT OmniBridge mediator operations are not verified automatically, so if the token does not allow read and write in the block explorer, follow the steps to verify the contract before starting.
The NFT OmniBridge mediator contract uses transferFrom functionality of the ERC721 token contract to pick the token from the owner; it must be explicitly approved to perform this operation.
Go to the token contract page in Etherscan and click on the "Write Contract"/"Write as Proxy" tab
Go to the approve method and enter the following:
to (address) field: the mediator contract address on the Kovan chain (
0x63be59CF177cA9bb317DE8C4aa965Ddda93CB9d7)tokenId (uint256): the id of the token to transfer (ids vary based on NFT implementation, may be a few digits or many)
Press the "Write" button to send the transaction.
Open the mediator contract (0x63be59CF177cA9bb317DE8C4aa965Ddda93CB9d7) in Etherscan and go to the "Write as Proxy" tab.
Scroll to the relayToken method. Enter the following:
token (address) field: the ERC721 token contract address the NFT is belongs to.
tokenId (uint256) field: the id of the token to transfer
Press Write to send the transaction.
The Arbitrary Message Bridge oracles will send their confirmations to the Sokol chain. As soon as enough confirmations received, the transfer will be automatically executed.
You can monitor this process using the AMB Live Monitoring tool: https://alm-test-amb.herokuapp.com/.
Specify the hash (tx id) of the transaction used to call relayToken in the ALM entry page and it will check the status of the AMB request initiated by this transaction in real time:
The link in "Executed by" section can be used to get more details about the terminating transaction:
The token can be observed by clicking on the Token Id in the "Token Transfer" tile:
The procedure to transfer ERC721 tokens from Sokol to Kovan differs from the transferring NFTs from Kovan to Sokol. It consists of three steps:
Approve the NFT OmniBridge mediator contract to operate with a non-fungible token.
Initiate a request to transfer the token through the bridge on the OmniBridge mediator contract.
Finalize the request by collecting the oracles' confirmations and transferring the Arbitrary Message Bridge contract on the Kovan side.
Make sure that the token contract is verified in BlockScout. Token contracts deployed as part of the NFT OmniBridge mediator operations are not verified automatically, so if the token does not allow read and write in the block explorer, follow the steps to verify the contract before starting.
The NFT OmniBridge mediator contract uses transferFrom functionality of the ERC721 token contract to pick the token from the owner; it must be explicitly approved to perform this operation.
Go to the token contract page in BlockScout and click on the "Write Contract"/"Write as Proxy" tab and go to the approve method. Enter the following:
to (address) field: the mediator contract address on the Sokol chain (
0x3ecEe2667f80fc0858437119621b820efc6b0Ede)tokenId (uint256): the id of the token to transfer
Press the "Write" button to send the transaction.
Open the mediator contract (0x3ecEe2667f80fc0858437119621b820efc6b0Ede) in BlockScout and go to the "Write Proxy" tab.
Scroll to the relayToken method. Enter the following:
token (address) field: the ERC721 token contract address the NFT is belongs to.
tokenId (uint256) field: the id of the token to transfer
Press Write to send the transaction.
The Arbitrary Message Bridge oracles will use the Sokol chain to collect confirmations of the NFT token transfer. As soon as the confirmations collected, it is necessary to relay the confirmations to the Kovan testnet to finalize the token transfer.
You can monitor this process using the AMB Live Monitoring tool: https://alm-test-amb.herokuapp.com/.
Specify the hash (tx id) of the transaction used to call relayToken in the ALM entry page and it will check the status of the AMB request initiated by this transaction in real time:
Change the chain in MetaMask/NiftyWallet to the Kovan chain and press Execute to send transaction to the Arbitrary Message Bridge contract with collected confirmations of the AMB oracles.
An alternative way to manually deliver confirmations to the AMB contracts on the Kovan side is to use the AMB Helper contract.
As soon as the transaction is verified and included in a block, the token will be transferred to the account that called the relayTokens method of the NFT OmniBridge mediator.
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