What is an Oracle?

An Oracle is a source of trusted information, often used to provide token prices.

You can check the data and status provided by vechain.energy's Oracles at https://status.oracle.vechain.energy (opens in a new tab)

If you choose to use the public deployment, we encourage you to run a reporter to enhance the oracle's decentralization. If this interests you, please open an issue (opens in a new tab) or send us an email at [email protected].

Data Evaluation

Each Oracle setup can manage multiple data feeds, each with its own settings.
Every URL in a feed is checked regularly, based on a configure interval.
We extract the median value from the results.
If the data on the blockchain is too old (based on a set 'heartbeat') or if it's too different from the current value (beyond a set percentage), we update the data on the blockchain.
You can always get the most recent value from an API, which allows for quicker access.

Contract Interface

The contract interface for all oracles is:

interface IVechainEnergyOracleV1 {
    // emitted when data changes
    event ValueUpdate(bytes32 id, uint128 value, uint128 updatedAt);
 
    // access value for a given feed id
    function getLatestValue(bytes32 id) external view returns (uint128 value, uint128 updatedAt);
 
    // allows everyone to update values using a verified & signed responses from the public API
    function updateValueWithProof(bytes memory message, bytes memory extraData, address signedFor) external;
}

id is a byte32 encoded version of the feed identifier (for example vet-usd)
value is the value provided by the oracle
updatedAt is the unix timestamp when the value was last determined

API Interface

A REST-API is publicly available for accessing the latest determined value and for administration purpose.

The OpenAPI definition can be found in the projects repository:

Source Code

The components needed to run the oracle are open-sourced. This helps developers build and manage oracle services on Vechain.

The project includes smart contracts for storing data on-chain and a backend that updates this on-chain data. The oracle service can be customized to support various data sources and multiple feeds. It also offers a public API to get the most recent data from sources, even if it hasn't been stored on-chain yet.

GitHub Link: https://github.com/vechain-energy/oracle.vechain.energy (opens in a new tab)

Virtual Proxy Node VET/USD (MainNet)