Storage of latest block number

The Oracle is getting the latest action from FIO history every 5 seconds. But when we restart the server, we read the all latest actions and calling wrap function from the start. Of course, it doesn't mint again but I think wrapping time can be long in this case. To prevent this problem, we need to save the latest block number to database or any external storage.what do you think about my suggest?

Casey Gardiner should we track block number in the oracleledger table?

• Suggest that Oracles store a log file of all the transactions locally. If they then go down they can grab a time stamp or transaction ID from the log file to know which transactions have not yet been processed.

• If an oracle server crashes and the logs are lost, then the oracle would have to re-process all transactions (and rebuild the log file). This would be a one time process.

• Decision: We will start with using log files, but will ask BPs their opinion on this solution.

Admin front-end UI

Is there a need for a front-end UI to review different transactions, or can we just rely on table lookups, etc.?

Pawel Mastalerz thoughts?

Process a single transaction at a time

Given the complexity of validating wrap and unwrap transactions all the way through to finality, both Todd and Alex have suggested that we limit oracles to only process a single transaction at a time

Alice (via dApp) called wraptokens inside the fio.oracle contract on FIO chain

fio.oracle contract actions:

• Parameter Validation ( ensuring amount, token codes, pubkey and fees are all properly set )

• Search oracle registration table (contains all registered oracles) and tally up the total number of registered oracles

• Collect Oracle fees, sort, and find the median.

• Send fee to all oracles.

• Emplace wrapping details inside the oracleldgrs table.

  

• Send the wrapped amount from Alice to fio.oracle contract.

• Collect BP fees

• Increase Alices RAM by 512.

• Send successful response to Alice

Oracle monitors wraptokens for transfers

• Method 1: Web socket subscription via Hyperion (similar to Solidity contract subscription).

  • Note this method requires extra setup on the Hyperion node to do streaming.

• Method 2: Poll fio.oracle actions using V1 history node.

TBD: Both methods require a history node so we should reach out to BPs with the requirements and ask which method they prefer

Finality Check:

• Oracle should monitor FIO chain for finality by ensuring block number is after the last_irreversible_block.

Oracle validates wraptokens transaction. If exceptions are found, Oracle takes action to unwind transaction

See Exception handling below

Oracle executes wrap on Ethereum chain

wrap(ethaddress, FIO (SUF) amount, obtid);
ex. wrap(“0x00000000000”, 10000000, “0x123456789”);

fio.erc20 contract actions:

• ethereum wallet provider (usually truffle/hd-wallet-provider) set to use oracles ethereum private key

• wFIO recipient eth address, wFIO amount to mint (must match what was wrapped on FIO chain exactly), and the obtid of the FIO transaction are provided as parameters to wrap action

• Transaction is executed

  • address provided receives wrapped FIO assets

  • event emitted:
    wrapped(address ethaddress, uint256 amount, uint256 obtid);

Oracle validates wrap transaction

• Oracles monitor all wrap transactions in process to ensure consensus has been reached.

• If a transaction is stuck in a pre-consensus state for some reason, a rollback should be triggered or a warning event should be thrown.

• Ensure finality. Don’t end up on a fork.

  • It is common to have transactions go into a mempool, and then transaction ends up in an uncle (orphan) block. If the transaction in the uncle block has not been validated elsewhere, then it should be returned to the mempool. But, there are situations where it can disappear from the mempool.

• How do transactions leave the memory pool?

• Why some transactions disappear from the mempool?

• Err on the side of waiting to make sure the block has reached finality.

• Only process one transaction at a time to reduce complexity.

Once all Oracles have submitted wrap, the wFIO Tokens will be minted and transferred to designated Ethereum public address

TBD: Does the oracle do any kind of monitoring or validation of the overall transaction (post consensus?)

TBD: What happens if the Oracle does not have enough ETH to cover the transaction? Does it roll back? Does it stay in the queue?

Invalid chain

Chain passed to wraptokens action is not Ethereum (Note: this restriction is not enforced in the FIO Contract to allow for wrapping chain expansion without deployment of code)

Oracle triggers unwraptokens action to send FIO back to originating address

TBD: How do other oracle get notified when a transaction is getting unwound?

TBD: What if one oracle approves the transaction and another oracle rejects?

Invalid Ethereum address

Public address passed to wraptokens action is not a valid Ethereum address (Note: this restriction is not enforced in the FIO Contract to allow for wrapping chain expansion without deployment of code)

Oracle triggers unwraptokens action to send FIO back to originating address

Alice (dApp) executes unwrap on Ethereum chain

unwrap(fio address, amount);
ex. unwrap(hard@edge, 100000000);

fio.erc20 contract actions:

• Alice provides amount to unwrap and the FIO Address for the oracle to send the FIO to as parameters to unwrap action

• Alice is paying gas fee for the unwrap

• Transaction executed:

  • wFIO amount is burned

  • event emitted:
    unwrapped(string fioaddress, uint256 amount);

Oracle monitors unwrap event for transfers

• Oracle subscribes to fio.erc20 events and reacts to the unwrap event

• No consensus is required for the unwrap transaction. Any oracle can initiate the FIO unwraptokens action.

  • TBD: How do we prevent multiple oracles from simultaneously initiating unwraptokens?

Oracle validates unwrap transaction

Validation includes:

• Has another Oracle already initiated the unwraptokens action on the FIO chain?

  • TBD: Other validations?

If exceptions are found, Oracle takes action to unwind transaction

See Exception handling below

Registered Oracles call upwraptokens inside the fio.oracle contract on FIO chain

fio.oracle contract Actions:

• Parameter Validation ( min/max amount, fio address check )

• Verify the actor is a registered oracle

• Find the fio.address inside the fionames table

• Search for previous votes of the same obt_id

  • If found

    • Search and verify actor has not voted prior

    • copy vector and push account name to list of voted oracles to the vector of votes

    • modify voters table with new vector

  • If not found

    • add actor to new vector

    • emplace new record with voters information

      

• Compare number of votes with number of registered oracles

  • if number of votes equal the number of registered oracles, transfer amount from fio.oracle contract to the fio.address provided.

• Send successful response to the oracle

Oracle validates unwraptokens transaction

• Oracles monitor all unwraptokens transactions in process to ensure consensus has been reached.

• If a transaction is stuck in a pre-consensus state for some reason, a rollback should be triggered or a warning event should be thrown.

Once all Oracles have submitted unwraptokens , the FIO Tokens will be transferred to designated Ethereum public address

TBD: Does the oracle do any kind of monitoring or validation of the overall transaction (post consensus?)

Invalid FIO Address

FIO Address passed in with ERC-20 is not valid or does not exist

Oracle triggers a ERC20 wrap action to send wFIO back to originating address

• TBD: What event is being monitored for this?