Reference → dAPIs

Verify dAPI sources ​

Datafeed values are stored on-chain within the Api3ServerV1.sol➚ contract and are updated on the basis of beaconIds.

A beaconId for each dAPI is derived from the hash of the provider's Airnode address and templateId.

A templateId is a hash of one of the Airnode's endpointId and encoded parameters.

The dAPI team is running Airseekers which are primarily responsible for updating the beaconId based on the specification of the dAPI. Providers also update the beaconId at a higher deviation threshold/heartbeat as a fallback.

To verify that the Airnode address of a beaconId belongs to the provider listed in the market, refer to the Verify Airnode Addresses section.

Verifying beaconId ​

From the API3 Market➚, navigate to the parameters page of a dAPI. As an example for ETH/USD on Gnosis chain➚ the parameters are as follows:

The templateId is calculated by taking the hash of the encodedParameters and endpointId.

Following is an ethers.js v5 script to derive the templateId (you need @airnode-abi installed):

import { encode } from '@api3/airnode-abi';
import { ethers } from 'ethers';

const encodedParameters = encode(decodedParameters);
const templateId = ethers.utils.solidityKeccak256(
  ['bytes32', 'bytes'],
  [endpointId, encodedParameters]
);

import { encode } from '@api3/airnode-abi';
import { ethers } from 'ethers';

const encodedParameters = encode(decodedParameters);
const templateId = ethers.utils.solidityKeccak256(
  ['bytes32', 'bytes'],
  [endpointId, encodedParameters]
);

Once derived the beaconId is the hash of the Airnode address and templateId:

import { ethers } from 'ethers';

const beaconId = ethers.utils.solidityKeccak256(
  ['address', 'bytes32'],
  [AirnodeAddress, templateId]
);

import { ethers } from 'ethers';

const beaconId = ethers.utils.solidityKeccak256(
  ['address', 'bytes32'],
  [AirnodeAddress, templateId]
);

Verifying beaconSetId ​

Beacon sets are a collection of beaconIds that provide the aggregated median value of the underlying beaconIds. The beaconSetId is a hash of all the underlying beaconIds and points to the datafeed containing the median value. Following is an ethers.js v5 script to derive the beaconSetId.

import { ethers } from 'ethers';

const beaconSetId = ethers.utils.keccak256(
  ethers.utils.defaultAbiCoder.encode(
    ['bytes32[]'],
    [[beaconId1, beaconId2, beaconId3]]
  )
);

import { ethers } from 'ethers';

const beaconSetId = ethers.utils.keccak256(
  ethers.utils.defaultAbiCoder.encode(
    ['bytes32[]'],
    [[beaconId1, beaconId2, beaconId3]]
  )
);