Introduction

Valuation asset and quotation asset

Each quotation track requires a unified amount of valuation asset and quotation asset. Thus, to participate in the price quotation, the maker needs to provide sufficient quotation asset with the same value as the valuation asset.

Take the ETH price quotation as one example, where the valuation asset is USDT, and its amount is 2000USDT. In this case, each quotation needs 2000USDT and 2000USDT-worthy ETH.

Quotation

The quotation participation needs to prepare valuation assets, quotation assets, quotation fees, and collateral assets (the collateral assets of all quotations are currently NEST). Valuation assets, quotation assets, and collateral assets can be used repeatedly in the contract without the need for transferring in every time (to save gas fees).

After the quotation, there will be a 5-minute verification period (practically calculated by block whose generation speed varies among different chains). After the 5-minute verification period, the maker can

1. close the current quotation and start the next one;
2. directly start the next quotation (if the relevant assets are sufficient) and close all of them after multiple quotations (which can save gas fees);
3. withdraw the quotation assets.

Verification

During the 5-minute verification period of one typical quotation, anyone can question the price and choose to trade either valuation or quotation asset. Suppose all of the quotation asset is traded; in that case, the quotation will not take effect (If only part of the quotation asset is traded, the price will still take effect after the verification period). While trading valuation or quotation assets, a verifier must submit a new quotation with asset scales twice as the just-traded transaction.

During verification, to issue a new quotation with twice the transaction size is to prevent malicious verification, which may cause the oracle to stop generating prices.

Quotation -> Verified Quotation -> Verified Quotation -> Verified Quotation -> …; One quotation and all subsequently verified quotations (generated based on this quotation) form a so-called price chain. For each of the first four quotation verifications, a verifier must submit a new quotation with valuation, quotation, and collateral assets twice the just-traded transaction size. Afterward, a verifier must double only collateral assets for a new quotation.

To prevent exogenous funds in the market from attacking the oracle, the protocol allows the verifiers, only four times, to double the sizes of the valuation and quotation assets. This restriction does not apply to the collateral asset since it is endogenous to the system.

Contract Address

ETH

BSC

Polygon

KCC

Price Calling

Price contract

mainnet

• ETH: 0xE544cF993C7d477C7ef8E91D28aCA250D135aa03
• BSC: 0x09CE0e021195BA2c1CDE62A8B187abf810951540
• Polygon: 0x09CE0e021195BA2c1CDE62A8B187abf810951540
• KCC: 0x7DBe94A4D6530F411A1E7337c7eb84185c4396e6

test

• ETH_rinkeby: 0xc08e6a853241b9a08225eecf93f3b279fa7a1be7
• BSC: 0xF2f9E62f52389EF223f5Fa8b9926e95386935277

Smart contract

Request Price(for contract)

Get the latest trigger price

Get the latest trigger price.The NEST price is a weighted average of all prices in the same block.New quotes and close operations trigger the calculation of prices that are already in effect earlier, while volatility and historical average prices are calculated.

function triggeredPrice(
    uint channelId,
    uint[] calldata pairIndices,
    address payback
) external payable returns (uint[] memory prices);

Off-chain reading(Prohibit contract use)

In block 14802456, 2000USDT = 0.069274BTC

Get the full information of latest trigger price

Get the latest departure price and average price volatility information.

function triggeredPriceInfo(
    uint channelId, 
    uint[] calldata pairIndices,
    address payback
) external payable returns (uint[] memory prices);

Off-chain reading(Prohibit contract use)

In block 14802456, 2000USDT=0.069274BTC, average price:2000USDT=0.069118234324991232BTC, volatility:17065492130

Find the price at block number

Find the price in effect on the target historical block, or if there is no offer on the target block, go forward and find the most recent price in effect.

function findPrice(
    uint channelId,
    uint[] calldata pairIndices, 
    uint height, 
    address payback
) external payable returns (uint[] memory prices);

Off-chain reading(Prohibit contract use)

In block 14802456, 2000USDT = 0.069274BTC

Get the last (num) effective price

Get the latest count of prices in effect.

function lastPriceList(
    uint channelId, 
    uint[] calldata pairIndices, 
    uint count, 
    address payback
) external payable returns (uint[] memory prices);

Off-chain reading(Prohibit contract use)

Read the latest 3 price information (BTC)

Returns lastPriceList and triggered price info

Returns both the lastPriceList and the triggeredPriceInfo interfaces.

function lastPriceListAndTriggeredPriceInfo(
    uint channelId, 
    uint[] calldata pairIndices,
    uint count, 
    address payback
) external payable returns (uint[] memory prices);

Off-chain reading(Prohibit contract use)

Read the latest 3 price information (BTC),average price,volatility

About channelId and pairIndex

Anyone can open a channel and make a quote on it. A channel can contain multiple price pairs (they all have the same currency unit of denomination). It is similar to a two-dimensional arrays that locates the price to be queried by channelId and pairIndex.

About the price call fee (for now)

Each call to the price method needs to carry a call fee, which is allocated by the administrator of the quote channel.Current fee is 0.

TriggeredPrice and LastPrice

triggeredPrice may be delayed by one price compared to lastPrice. In most cases, they are the same. It depends on the offer density. triggeredPrice requires less gas consumption, lastPrice must have the latest price, but has higher gas consumption.

Price token and Price token unit

All prices in the documentation are in 2000 USDT, which is not fixed. Each channel has its own Price token and Price token unit, please check it before calling.

Channel Information-Website

Read channel information from the contract

Web display prices

web shows 1 ETH = 2500 USDT, get ETH price data as 800000000000000000(decimals 18), which means 2000 USDT = 0.8 ETH. Web converted to show.

Call example

The example environment is the ethereum rinkeby test network.

• Contract:0xc08e6a853241b9a08225eecf93f3b279fa7a1be7
• ChannelId:0
• Fee:0

FORT:Use Instant Price

FORT Smart contract

    // Query latest 2 price
    function _lastPriceList(
        TokenConfig memory tokenConfig, 
        uint fee, 
        address payback
    ) internal returns (uint[] memory prices) {

        // -----GET NEST PRICE-----
        prices = INestBatchPrice2(NEST_OPEN_PRICE).lastPriceList {
            value: fee
        } (uint(tokenConfig.channelId), _pairIndices(uint(tokenConfig.pairIndex)), 2, payback);
        // -----GET NEST PRICE-----

        prices[1] = _toUSDTPrice(prices[1]);
        prices[3] = _toUSDTPrice(prices[3]);
    }

    // Query latest price
    function _latestPrice(
        TokenConfig memory tokenConfig, 
        uint fee, 
        address payback
    ) internal returns (uint oraclePrice) {

        // -----GET NEST PRICE-----
        uint[] memory prices = INestBatchPrice2(NEST_OPEN_PRICE).lastPriceList {
            value: fee
        } (uint(tokenConfig.channelId), _pairIndices(uint(tokenConfig.pairIndex)), 1, payback);
        // -----GET NEST PRICE-----

        oraclePrice = _toUSDTPrice(prices[1]);
    }

    // Find price by blockNumber
    function _findPrice(
        TokenConfig memory tokenConfig, 
        uint blockNumber, 
        uint fee, 
        address payback
    ) internal returns (uint oraclePrice) {

        // -----GET NEST PRICE-----
        uint[] memory prices = INestBatchPrice2(NEST_OPEN_PRICE).findPrice {
            value: fee
        } (uint(tokenConfig.channelId), _pairIndices(uint(tokenConfig.pairIndex)), blockNumber, payback);
        // -----GET NEST PRICE-----

        oraclePrice = _toUSDTPrice(prices[1]);
    }

Parasset:Use the average price

Parasset Smart contract

    /// @dev Get price
    /// @param token mortgage asset address
    /// @param uToken underlying asset address
    /// @param payback return address of excess fee
    /// @return tokenPrice Mortgage asset price(2000U = ? token)
    /// @return pTokenPrice PToken price(2000U = ? pToken)
    function getPriceForPToken(
        address token, 
        address uToken,
        address payback
    ) public payable override returns (
        uint256 tokenPrice, 
        uint256 pTokenPrice
    ) {
        if(uToken == address(USDT_ADDRESS)) {
            uint256[] memory pricesIndex = new uint256[](1);
            pricesIndex[0] = addressToPriceIndex[token];

            // -----GET NEST PRICE-----
            uint256[] memory prices = _nestBatchPlatform.triggeredPriceInfo{value:msg.value}(CHANNELID, pricesIndex, payback);
            // -----GET NEST PRICE-----

            require(prices[2] > 0, "Log:PriceController:!avg");
            return(prices[2], BASE_USDT_AMOUNT);
        } else {
            uint256[] memory pricesIndex = new uint256[](2);
            pricesIndex[0] = addressToPriceIndex[token];
            pricesIndex[1] = addressToPriceIndex[uToken];

            // -----GET NEST PRICE-----
            uint256[] memory prices = _nestBatchPlatform.triggeredPriceInfo{value:msg.value}(CHANNELID, pricesIndex, payback);
            // -----GET NEST PRICE-----

            require(prices[2] > 0 && prices[6] > 0, "Log:PriceController:!avg");
            return(prices[2], prices[6]);
        }
    }

Preventing drastic price fluctuations

Market prices sometimes fluctuate too much, and there are some precautions to take when using prices, such as: comparing the deviation of the instant price with the average price, and not continuing to trade if it is too large.

CoFix Smart contract

    /// @dev Query latest price info
    /// @param tokenAddress Target address of token
    /// @param payback As the charging fee may change, it is suggested that the caller pay more fees, 
    /// and the excess fees will be returned through this address
    /// @return blockNumber Block number of price
    /// @return priceEthAmount Oracle price - eth amount
    /// @return priceTokenAmount Oracle price - token amount
    /// @return avgPriceEthAmount Avg price - eth amount
    /// @return avgPriceTokenAmount Avg price - token amount
    /// @return sigmaSQ The square of the volatility (18 decimal places)
    function latestPriceInfo(address tokenAddress, address payback) 
    external 
    payable 
    override
    returns (
        uint blockNumber, 
        uint priceEthAmount,
        uint priceTokenAmount,
        uint avgPriceEthAmount,
        uint avgPriceTokenAmount,
        uint sigmaSQ
    ) {

        // -----GET NEST PRICE-----
        (
            blockNumber, 
            priceTokenAmount,
            ,//uint triggeredPriceBlockNumber,
            ,//uint triggeredPriceValue,
            avgPriceTokenAmount,
            sigmaSQ
        ) = INestPriceFacade(NEST_PRICE_FACADE).latestPriceAndTriggeredPriceInfo { 
            value: msg.value 
        } (tokenAddress, payback);
        // -----GET NEST PRICE-----

        _checkPrice(priceTokenAmount, avgPriceTokenAmount);
        priceEthAmount = 1 ether;
        avgPriceEthAmount = 1 ether;
    }