Optimistic Oracle V2

Get off Chain data Optimistically on-chain using UMA's oracle

The OO is an oracle for arbitrary off-chain data which leverages an interactive escalation game between requesters, proposers and disputers and is secured by economic incentives.

There are multiple type of identifiers available like Prices , YES_OR_NO queries , Price Indexes, Insurance Claims , etc. More Approved identifiers can be found here :-

Approved Price Identifiers | UMA Documentationdocs.uma.xyz

You will be working through a simple smart contract that asks the oracle the question: Q:Did the temperature on the 25th of July 2022 in Manhattan NY exceed 35c? A:1 for yes. 0 for no. After submitting the request, you will propose a solution using the UMA Optimistic Oracle UI.

Using OO v2

• Start by importing the datum-contracts package

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.14;

import "datum-contracts/interfaces/OptimisticOracleV2Interface.sol";

• Create the contracts instance with the OOv2 Oracle Contract address

  // For Sepolia 
oracleAddress = 0x3CBb6Dbe62CB2D2Daa2019B44d5D19C46AB9Dc45
  
OptimisticOracleV2 oo =
        OptimisticOracleV2(oracleAddress);

• Add the identifier as what type of oracle Data you are requesting , more info on identifier is available here

   bytes32 identifier = bytes32("YES_OR_NO_QUERY");

• Now ancillaryData needs to be added , it depends on type of identifier , details can be found on UMA docs

    bytes ancillaryData =
        bytes(
            "Q:Did the temperature on the 25th of July 2022 in Manhattan NY exceed 35c? A:1 for yes. 0 for no."
        );

• Next , we need to create a Request to the Optimistic Oracle V2 , with bondCurrency , rewards and the liveness time using requestData .

    function requestData() public {
        uint requestTime = block.timestamp; // Set the request time to the current block time.
        address bondCurrency = 0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6; // Use Görli WETH as the bond currency.
        uint256 reward = 0; // Set the reward to 0 (so we dont have to fund it from this contract).

        requestId = oo.requestData(
            identifier,
            ancillaryData,
            bondCurrency,
            reward,
            30
        );
    }

Currently rewards are not supported via DATUM oracles, so bondCurrenct and reward needs to be default

• Later , Proposer will propose the answer , and disputor might dispute too under liveness time. You can also propose the answer yourself here

• After the voting ends , settleRequest needs to be called from Oracle , to complete and get the result

    function settleRequest() public {
        oo.settleRequest(requestId);
    }

• Get request result using getRequestResult from Oracle

 function getSettledData() public view returns (int256) {
        return oo.getRequestResult(requestId);
    }

Full Example Contract

// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity ^0.8.14;

// *************************************
// *   Minimum Viable OO Intergration  *
// *************************************

// This contract shows how to get up and running as quickly as posible with UMA's Optimistic Oracle.
// We make a simple price request to the OO and return it to the user.

import "datum-contracts/interfaces/OptimisticOracleV2Interface.sol";

contract OOV2Test {
    // Create an Optimistic oracle instance at the deployed address on Görli.
    OptimisticOracleV2 oo =
        OptimisticOracleV2(0x3CBb6Dbe62CB2D2Daa2019B44d5D19C46AB9Dc45);

    // Use the yes no idetifier to ask arbitary questions, such as the weather on a particular day.
    bytes32 identifier = bytes32("YES_OR_NO_QUERY");

    // Post the question in ancillary data. Note that this is a simplified form of ancillry data to work as an example. A real
    // world prodition market would use something slightly more complex and would need to conform to a more robust structure.
    bytes ancillaryData =
        bytes(
            "Q:Did the temperature on the 25th of July 2022 in Manhattan NY exceed 35c? A:1 for yes. 0 for no."
        );

    uint256 requestTime = 0; // Store the request time so we can re-use it later

    uint requestId;

    // Submit a data request to the Optimistic oracle.
    function requestData() public {
        requestTime = block.timestamp; // Set the request time to the current block time.
        address bondCurrency = 0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6; // Use Görli WETH as the bond currency.
        uint256 reward = 0; // Set the reward to 0 (so we dont have to fund it from this contract).

        requestId = oo.requestData(
            identifier,
            ancillaryData,
            bondCurrency,
            reward,
            30
        );
    }

    // Settle the request once it's gone through the liveness period of 30 seconds. This acts the finalize the voted on price.
    // In a real world use of the Optimistic Oracle this should be longer to give time to disputers to catch bat price proposals.
    function settleRequest() public {
        oo.settleRequest(requestId);
    }

    // Fetch the resolved price from the Optimistic Oracle that was settled.
    function getSettledData() public view returns (int256) {
        return oo.getRequestResult(requestId);
    }
}

In this way , you can use Optimistic Oracle V2 in simple steps , extra info is available on the UMA docs