OoO Quickstart

Integration

In order to request data, and enable data provision in your smart contract, you will need to import the ConsumerBase.sol smart contract and set up two simple functions within your smart contract.

1. Add the package to your project:

yarn add @unification-com/xfund-router

2. In your smart contract, import ConsumerBase.sol:

import "@unification-com/xfund-router/contracts/lib/ConsumerBase.sol";

3. Extend your contract, adding is ConsumerBase:

contract MyConsumer is ConsumerBase {

4. Ensure your constructor function has a parameter to accept the Router and xFUND smart contract addresses, and pass it to the ConsumerBase:

constructor(address _router, address _xfund)
    public ConsumerBase(_router, _xfund) {
        // other stuff...
    }

Note

See Contract Addresses for the latest contract addresses

5. Implement the receiveData function for data Providers to send data, e.g.

function receiveData(uint256 _price, bytes32 _requestId) internal override {
    price = _price;
}

Note

Thus must be internal and override the ConsumerBase's receiveData.

6. Implement a function to request data, for example:

function getData(address _provider, uint256 _fee, bytes32 _data) external returns (bytes32) {
    return _requestData(_provider, _fee, _data);
}

7. Deploy. For example, using truffle, a very simple migration script for Rinkeby testnet may look like:

// Load my contract which implements ConsumerLib
const MyConsumer = artifacts.require("MyConsumer")

module.exports = function(deployer) {
  // deploy, passing the Router and xFUND smart contract addresses
  deployer.deploy(MyConsumer, "0x...ROUTER_ADDRES", "0x...XFUND_ADDRESS")
}

Initialisation

Once integrated, compiled and deployed, you will need to send some transactions to the Ethereum blockchain in order to initialise the fee payment, and data acquisition environment. This involves:

1. Increasing the xFUND token allowance on the Router smart contract, in order for the Router to accept and pay xFUND fees to data providers. This need only be run once, if the initial allowance is set high enough. A function is available in the ConsumerBase contract to facilitate this, which can be wrapped around a function in your contract.

2. Transfer some xFUND tokens to your smart contract, that is integrating ConsumerBase. This allows you to submit data requests, and your contract to pay fees. The required amount of xFUND to pay for a request fee is sent to the Router with each request. Your contract may need periodically topping up with xFUND, depending on how you implement fee payment.

   Note: The xFUNDMOCK Token on Rinkeby testnet has a faucet function, gimme() which can be used to grab some test tokens.

Once these steps have been run through, you will be able to initialise data requests via your smart contract.