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.?

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

Oracle Initialization

• Set the initial value of actionIndex = last_irreversible_block number (from FIO Chain) when server starts.

• TBD: What is the best way to store the actionIndex to persist when an Oracle restarts?

  • See “Storage of latest block number” above

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

Example: Calling wraptokens using Cryptonym:

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fio.oracle contract actions

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.

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

• Collect FIO/BP fees

• Increase Alices RAM by 512.

• Send successful response to Alice

Oracle monitors get_actions API on V1 History node

Every 5 seconds Oracle polls the get_actions API on History node Plugin to detect activity on the wrapping account (e.g. "o2ouxipw2rt4")

curl -s -XPOST http://44.242.158.42:8080/v1/history/get_actions -d '{
  "account_name": "o2ouxipw2rt4",
  "pos": -1
}'

1. Retrieve all actions

2. For each action, if block_num > actionIndex then validate and process the action (call ERC-20 wrap)

3. Set actionIndex = block_num of most recent wraptokens action

const actionIdx = config.oracleCache.get("actionIndex");
          const dataLen = Object.keys(data.data.actions).length;
          var array = Array();
          for (var i = 0; i<dataLen;i++){
            if (data.data.actions[i].block_num > actionIdx) {
                array.push(data.data.actions[i]);
            }
            config.oracleCache.set("actionIndex", data.data.actions[dataLen-1].block_num)
          }
          return array;

TBD:

• Since there eventually may be very many transactions, it may make sense to walk backward through the table using "pos" and "offset". Maybe you grab the most recent 5 actions and see if any of them are new. If ALL of them are new, then you need to grab the next 5 actions, etc.

wrap transaction finality monitoring on FIO Chain

• TBD: Should the oracle monitor FIO chain for finality by ensuring block number is after the last_irreversible_block?

  • Yes, wait for finality.

Oracle validates the FIO chain wraptokens transaction.

• See “Exception handling” below

• Check the actions to confirm it is a wrapping action:

if (wrapData[i].action_trace.act.data.memo == "Token Wrapping")

Responding to invalid wraptokens transaction

• TBD: If exceptions are found, what actions does the Oracle take unwind wraptokens action?

Oracle executes wrap on fio.erc20 contract on Ethereum chain

• 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

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

fio.erc20 contract actions for pre-consensus calls to wrap function

fio.erc20 contract actions:

• (Not sure what this means?) ethereum wallet provider (usually truffle/hd-wallet-provider) set to use oracles ethereum private key

• See: https://fioprotocol.atlassian.net/wiki/spaces/FD/pages/91062320/fio.erc20+-+wFIO+Contract+Specification#Exception-handling

• When the initial oracles call wrap:

  • Contract sends an event.

  • The oracle receives the Event and the Ethereum Transaction ID (if successful)

  • The oracle alerts the user about wrapping result

  • Example wrap transaction: https://ropsten.etherscan.io/tx/0x3a90be65ad89fc5572890eb24d7790bed7d5ebf1797f2755278afbab3e9c6830

• TBD: There will be three different transaction IDs by the erc20 contract (two wrap transactions and one wrap/mint transaction) generated from three different Oracles. How does this information make it back to Alice who called wraptokens on the FIO chain? Should the oracle surface an Event? If so, what is listening to that event? Do we assume that the user is using an app that is able to listen to the erc20 events? All of this kind of assumes there is an App that the user is using to wrap tokens… Pawel Mastalerz

  • Same thing for unwrap

fio.erc20 contract actions for final consensus call to wrap function

Example of three oracles calling wrap:

Using these oracle, we call the wrap function on FIO token contract using web3.js like below.
instance.wrap[accounts[5], 10000, "99e20de9bb9f178f3ff1328c089925daff1d5dcb1da7dceaad7fc5126a08eaf5". {from: accounts[1]}); 
instance.wrap[accounts[5], 10000, "99e20de9bb9f178f3ff1328c089925daff1d5dcb1da7dceaad7fc5126a08eaf5". {from: accounts[2]}); 
instance.wrap[accounts[5], 10000, "99e20de9bb9f178f3ff1328c089925daff1d5dcb1da7dceaad7fc5126a08eaf5". {from: accounts[3]});

• TBD: If an Oracle does not have enough ETH to cover the transaction, the transaction remains in the partially completed state until the Oracle obtains more ETH and executes the transaction. Need to confirm.

  • How do we notify the oracle operator that there is a problem? Pawel Mastalerz

• When the last oracle calls wrap, the transaction is executed

  • The mint function inside wrap is automatically executed

  • The Ethereum address provided receives wrapped FIO assets

  • An Event is emitted by the ERC-20 contract: wrapped(address ethaddress, uint256 amount, uint256 obtid);

  • The oracle receives the Event and the Ethereum Transaction ID (if successful) and alerts the user about wrapping result

  • This final transaction will include a mint action.

  • Example wrap transaction: https://ropsten.etherscan.io/tx/0x3a90be65ad89fc5572890eb24d7790bed7d5ebf1797f2755278afbab3e9c6830

ERC-20 wrap validation

TBD: Adam to document how the contract handles invalid failed transactions. Put link to content here. Adam Androulidakis

• Discussion with Eric/Adam: The current thinking is that if any one of the three transactions ( 2 wrap transactions and 1 wrap/mint transaction) fails, they will all fail. So, if for some reason one of the initial two wrap transactions

• fails, even though the wrap/mint transaction was initiated, it will eventually fail as well. This needs to be tested.

  • Adam Androulidakis will diagram out the flow of how this works.

Responding to invalid ERC-20 wrap transaction

TBD: Any kind of recovery? Just send a failure message to the user and note that their FIO is stuck in the FIO wrapping account? Pawel Mastalerz

wrap transaction finality monitoring on Ethereum

• Alice receives the Ethereum Transaction ID and is responsible for monitoring the status.

  • TBD: Unless Alice is using some kind of custom application, she only has access to her Ethereum address and has to sit there and wait to see if WFIO appears. Is this the expectation?

  • TBD: If Alice sees that it has failed, what does she do? Pawel Mastalerz

• Does the oracle do any kind of monitoring or validation of the overall transaction (beyond responding to the ERC-20 Event)

  • Decision: Based on 5/13 discussion with Luke/Pawel/Dev team, no additional monitoring of the transaction on the Ethereum chain is required.

  • Decision: Based on 5/13 discussion with Luke/Pawel/Dev team, only limited monitoring of the transaction on the Ethereum chain is required.

  • All of the following do NOT need to be monitored or tracked by the Oracle:

    • A transaction gets stuck in a pre-consensus state.

    • A transaction disappears (e.g., ending up on a fork, etc.)

      • 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.

    • Waiting to make sure the block has reached finality.

• TBD: Only process one transaction at a time to reduce complexity?

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

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?