Implementation

Creating your invokable smart contract

First we’ll walk through how to set up your own contract which will be invoked via Kollateral.

Install the Kollateral solidity library to your truffle project which provides interfaces, base contracts, and useful utils.

npm install @kollateral/contracts

Extending from the KollateralInvokable base contract provides the interfaces and helper methods necessary to build a basic contract.

import "@kollateral/contracts/invoke/KollateralInvokable.sol";

contract MyContract is KollateralInvokable {
  constructor () public { }

  function execute(bytes calldata data) external payable {
    // liquidate
    // swap
    // refinance
    // etc...
    repay();
  }
}

In this example execute(bytes) will be invoked after Kollateral aggregates and transfer the requested funds to your contract.

Invoking via JS with Web3

There are multiple ways to call Kollateral. Here we’ll dive into how to call it directly from web3, using Kollateral as your entrypoint to the blockchain.

Install the Kollateral typescript library.

npm install @kollateral/kollateral

In this example we use the ethereum provider that MetaMask injects, any Web3 provider may be used in its place. Configurations are loaded based on the networkId of the provider.

import { Kollateral, Token } from '@kollateral/kollateral'

const kollateral = await Kollateral.init(ethereum);

kollateral.invoke({
  to: myContractAddress
}, {
  token: Token.DAI,
  amount: web3.utils.toWei(1000)
}).then(() => console.log("success!");

Invoking via solidity

Kollateral can also by invoked directly from within a contract.

Ensure that the Kollateral solidity library is installed.

npm install @kollateral/contracts

In this example we make a basic call to the Kollateral invoker, this can be done anywhere within your contract.

import "@kollateral/contracts/invoke/IInvoker.sol";

address internal _invokerAddress;

function myMethod() external payable {
  address to;
  bytes memory data;
  address tokenAddress;
  uint256 tokenAmount;

  IInvoker(_invokerAddress).invoke(to, data, tokenAddress, tokenAmount);
}

Keep in mind that invoke is also optionally payable. Any funds sent will be passed on along to your invokable contract during execution.

Passing data to execute

An invokable contract takes a single bytes in its execute() function. Clever use of abi encoding can extend this for any use case.

In this example we’ll send in a simple payload with a few easy parameters’

script.js

const data = ethers.utils.defaultAbiEncoder.encode(["uint256", "bytes"], ["123", "0x4568"]);

/* contract.sol */
function execute(bytes calldata data) external payable {
  (uint256 myNum, bytes memory myData) = abi.decode(data, (uint256, bytes));

  // use params

  repay();
}

Encoded data strings may be nested to create more complex parameter data structures.