Getting Started with Fact Finance on XDC

Luciano — Tue, 28 Jan 2025 03:28:23 +0000

The Fact Finance is a Sync Oracle designed for efficiency and scalability in Web3. Unlike traditional oracles that require constant querying by smart contracts (pull model), the push oracle actively syncs critical economic data on-chain, making it instantly available for smart contract consumption.

Our push oracle supports a wide range of real-world data types, including:

Exchange rates
Interest rates
Inflation indices
Proof-of-reserve data for tokenized assets

Getting Started

The FOInterfaceV1 contract provides an interface for interacting with the synchronous (push) version of the Fact Oracle, where data is periodically updated on-chain. This guide explains how to use the interface to retrieve data feeds, manage subscriptions, and ensure best practices when working with Fact Oracle services.

Installation

Import the Interface:
Include the FOInterfaceV1.sol file in your Solidity project:

import "./FOInterfaceV1.sol";

Contract Initialization:

Obtain the address of a contract that implements the FOInterfaceV1 interface from the chain list.

Usage

Return Type - DataFeed Struct

The DataFeed struct represents the oracle data feed, including the value, confidence score, and metadata for interpretation. This is how the data is structured:

/// @title Data Feed Struct
/// @notice Represents the data feed with a value, timestamp, and confidence level
/// @dev Stores oracle data with additional metadata for reliability and scaling
struct DataFeed {
    int128 value;        /// @dev Integer value of the data feed, representing the main metric or value.
    uint64 updatedAt;    /// @dev Timestamp (in seconds) when the backend last updated this data feed.
    uint8 decimal;       /// @dev Number of decimal places for the data value (e.g., 2 for cents, 6 for micro-units).
    uint8 confidence;    /// @dev Confidence level of the data feed (0: outlier, 5: acceptable, 95: highly reliable).
    bytes6 info;         /// @dev Encoded additional information about the data feed (e.g., metadata or tags).
}

Explanation:

value:

The raw integer data from the oracle. To derive the actual value, multiply value by 10^-decimal.
Example: If value = 12345 and decimal = 2, the actual value is 123.45.

updatedAt:

The timestamp indicating when the data was last updated.
Important: Use this to verify the freshness of the data and ensure it hasn’t expired before using it in smart contracts.

decimal:

Indicates how many decimal places the value needs for interpretation.

confidence:

Represents the reliability of the data feed:
0: Outlier (use with caution).
5: Acceptable (mild volatility).
95: Reliable (highly trustworthy).

info:

Encoded extra information about the data feed, which can contain metadata or tags. For example:
For a CPI (Consumer Price Index) feed, info might include the month, last 12 months, and last change.

Interacting with FOInterfaceV1

Initialization Set up your contract with the Fact Oracle address:

constructor(address _oracle) {
    fOracle = FOInterfaceV1(_oracle);
}

Methods

getSyncData(): Retrieve the latest data feed for a specific code.

Parameter:
code (uint16): The identification code of the feed. Codes for various feeds can be found at DataFeed List.
Example:

function getSyncData(uint16 code) public {
    DataFeed memory data = fOracle.getSyncData(code); 
    // Calculate actual value
    int256 actualValue = data.value * int256(10 ** data.decimal);
    // Check if data is fresh
    require(block.timestamp - data.updatedAt < 3600, "Data expired"); // 1-hour limit
}

Freemium Oracle Model

The Fact Oracle operates on a freemium model. Most data feeds, such as economic indices and public data, are free to access. Licensed data feeds require a subscription.

Best Practices

Restrict Oracle Updates:
Always use a restricted modifier (e.g., onlyOwner) to update the oracle address securely.

function updateOracle(address _oracle) public onlyOwner {  
    fOracle = FOInterfaceV1(_oracle);
}

Validate Freshness:
Ensure data retrieved from the oracle is not expired by comparing data.updatedAt with the current block timestamp.

Handle Confidence Levels:
Implement logic to treat confidence appropriately. For example:

Reject feeds with confidence = 0.
Use stricter rules for confidence = 5.
Fully trust data with confidence = 95.

Use Decimals Correctly:
Always factor in decimal when calculating or displaying the data value.

With these steps and best practices, you can seamlessly integrate Fact Oracle services into your smart contracts while ensuring security, accuracy, and efficiency.

XDC RWA Oracle for Latin America

Luciano — Fri, 06 Dec 2024 14:39:31 +0000

🚀 Attention #Developers on the @XDCNetwork!

Fact Finance is now live on #XDC, providing seamless access to Brazilian and Argentine economic indices like CDI (interest rates) and CPI (inflation) through our reliable oracle.

🔧 This integration is built with developers in mind, offering you official, compliant data from trusted sources to power secure and accurate dapps, especially in #DeFi and tokenization projects.

💡 With Fact Finance, you can effortlessly incorporate real-world economic data into your applications, enhancing trust, functionality, and user experience. Whether you’re building lending platforms, stablecoins, or tokenized assets, our tools are here to simplify the process.

Stay tuned for more updates in the next post! In the meantime, explore our GitHub and start building today: https://github.com/FactFinance

Be in touch xdc@fact.finance

RWA #oracle #Latam #DevTools

Developers Forum for XinFin XDC Network: Luciano