You can use Chainlink to trigger a smart contract at a specified time. Using this Chainlink, you will create a request with a timestamp for the node to call back to your desired function. You can include additional logic in that function to perform additional computation.

• Write and deploy your Chainlinked contract using the network details below
• Fund it with LINK (1 LINK is required per-request)
  • Ropsten faucet
  • Rinkeby faucet
  • Kovan faucet
• Call your request method

You will need to use the following LINK token address, oracle address, and JobSpec ID in order to create the Chainlink request.

Ropsten

LINK Token address: 0x20fE562d797A42Dcb3399062AE9546cd06f63280
Oracle address: 0xc99B3D447826532722E41bc36e644ba3479E4365
JobID: 2ebb1c1a4b1e4229adac24ee0b5f784f

Rinkeby

LINK token address: 0x01BE23585060835E02B77ef475b0Cc51aA1e0709
Oracle address: 0x7AFe1118Ea78C1eae84ca8feE5C65Bc76CcF879e
JobID: 4fff47c3982b4babba6a7dd694c9b204

Kovan

LINK token address: 0xa36085F69e2889c224210F603D836748e7dC0088
Oracle address: 0x2f90A6D021db21e1B2A077c5a37B3C7E75D15b7e
JobID: a7ab70d561d34eb49e9b1612fd2e044b

Import Chainlinked.sol into your contract so you can inherit the Chainlinked behavior.

pragma solidity ^0.4.24;

import "chainlink/contracts/ChainlinkClient.sol";

contract ChainlinkAlarmClock is ChainlinkClient {

  uint256 oraclePayment;

  constructor(uint256 _oraclePayment) public {
    setPublicChainlinkToken();
    oraclePayment = _oraclePayment;
  }
  // Additional functions here:
  
}

• Sleep
• EthBool
• EthTx

until

Required

The timestamp for which the Chainlink node will wait to respond.

Solidity example

req.addUint("until", now + 5 minutes);

This example shows how to create the request for the Chainlink node:

function delayStart
(
  address _oracle,
  bytes32 _jobId
)
  public
  onlyOwner
{
  Chainlink.Request memory req = buildChainlinkRequest(_jobId, this, this.fulfill.selector);
  req.addUint("until", now + 5 minutes);
  sendChainlinkRequestTo(_oracle, req, oraclePayment);
}

This example shows the callback method:

function fulfill(bytes32 _requestId)
  public
  recordChainlinkFulfillment(_requestId)
{
  /* additional computation here */
}