Developers building on Binance Smart Chain can now leverage Band's decentralized oracle infrastructure. With Band's oracle, they now have access to various cryptocurrency price data to integrate into their applications.
Currently, the following token symbols are supported. Going forward, this list will continue to expand based on developer needs and community feedback.
Token Name | Symbol |
---|---|
Binance Coin | BNB |
Binance USD | BUSD |
Bitcoin | BTC |
Ethereum | ETH |
Tether | USDT |
XRP | XRP |
Chainlink | LINK |
Polkadot | DOT |
Bitcoin Cash | BCH |
Litecoin | LTC |
Cardano | ADA |
Bitcoin SV | BSV |
Crypto.com Coin | CRO |
EOS | EOS |
Tezos | XTZ |
Tron | TRX |
Stellar | XLM |
Cosmos | ATOM |
Monero | XMR |
OKB | OKB |
Swipe | SXP |
Linear Finance | LINA |
The method provided below supports price query with any denomination as long as the base and quote symbols are supported in the list above.
For example, you can use the APIs in Javascripts and Solidity to query the following price pairs:
BTC/USD
BNB/ETH
Currently, there are two methods for developers to query prices from Band's oracle: through Band's StdReference
smart contract on Binance Smart Chain and through their bandchain.js
JavaScript helper library.
To query prices from Band's oracle through smart contracts, the contract looking to use the price values should reference Band's StdReference
contract. This contract exposes getReferenceData
and getReferenceDataBulk
functions.
getReferenceData
takes two strings as the inputs, the base and quote symbol, respectively. It then queries the StdReference
contract for the latest rates for those two tokens, and returns a ReferenceData
struct, shown below.
struct ReferenceData {
uint256 rate; // base/quote exchange rate, multiplied by 1e18.
uint256 lastUpdatedBase; // UNIX epoch of the last time when base price gets updated.
uint256 lastUpdatedQuote; // UNIX epoch of the last time when quote price gets updated.
}
getReferenceDataBulk
instead takes two lists, one of the base
tokens, and one of the quotes
. It then proceeds to similarly queries the price for each base/quote pair at each index, and returns an array of ReferenceData
structs.
For example, if we call getReferenceDataBulk
with ['BTC','BTC','ETH']
and ['USD','ETH','BNB']
, the returned ReferenceData
array will contain information regarding the pairs:
BTC/USD
BTC/ETH
ETH/BNB
The contract code below demonstrates a simple usage of the new StdReference
contract and the getReferenceData
function.
pragma solidity 0.6.11;
pragma experimental ABIEncoderV2;
interface IStdReference {
/// A structure returned whenever someone requests for standard reference data.
struct ReferenceData {
uint256 rate; // base/quote exchange rate, multiplied by 1e18.
uint256 lastUpdatedBase; // UNIX epoch of the last time when base price gets updated.
uint256 lastUpdatedQuote; // UNIX epoch of the last time when quote price gets updated.
}
/// Returns the price data for the given base/quote pair. Revert if not available.
function getReferenceData(string memory _base, string memory _quote)
external
view
returns (ReferenceData memory);
/// Similar to getReferenceData, but with multiple base/quote pairs at once.
function getReferenceDataBulk(string[] memory _bases, string[] memory _quotes)
external
view
returns (ReferenceData[] memory);
}
contract DemoOracle {
IStdReference ref;
uint256 public price;
constructor(IStdReference _ref) public {
ref = _ref;
}
function getPrice() external view returns (uint256){
IStdReference.ReferenceData memory data = ref.getReferenceData("BTC","USD");
return data.rate;
}
function getMultiPrices() external view returns (uint256[] memory){
string[] memory baseSymbols = new string[](2);
baseSymbols[0] = "BTC";
baseSymbols[1] = "ETH";
string[] memory quoteSymbols = new string[](2);
quoteSymbols[0] = "USD";
quoteSymbols[1] = "USD";
IStdReference.ReferenceData[] memory data = ref.getReferenceDataBulk(baseSymbols,quoteSymbols);
uint256[] memory prices = new uint256[](2);
prices[0] = data[0].rate;
prices[1] = data[1].rate;
return prices;
}
function savePrice(string memory base, string memory quote) external {
IStdReference.ReferenceData memory data = ref.getReferenceData(base,quote);
price = data.rate;
}
}
Blockchain | Aggregator Contract Address | Update Every | Explorer |
---|---|---|---|
BSC (Testnet) | 0xDA7a001b254CD22e46d3eAB04d937489c93174C3 |
5 mins | link |
BSC (Mainnet) | 0xDA7a001b254CD22e46d3eAB04d937489c93174C3 |
5 mins | link |
Band's node helper library bandchain.js
also supports a similar getReferenceData
function. This function takes one argument, a list of token pairs to query the result of. It then returns a list of corresponding rate values.
The code below shows an example usage of the function
const BandChain = require('@bandprotocol/bandchain.js');
(async () => {
const endpoint = 'https://poa-api.bandchain.org';
const bandchain = new BandChain(endpoint);
const price = await bandchain.getReferenceData(['BAND/USD', 'BTC/ETH', 'EUR/USD', 'EUR/BTC']);
console.log(price);
})();
The corresponding result will then be similar to
$ node index.js
[
{
pair: 'BAND/USD',
rate: 6.49,
updated: { base: 1600676205, quote: 0 },
rawRate: { value: 6490000000n, decimals: 9 }
},
{
pair: 'BTC/ETH',
rate: 29.574702955490906,
updated: { base: 1600676187, quote: 1600676187 },
rawRate: { value: 29574702955n, decimals: 9 }
},
{
pair: 'EUR/USD',
rate: 1.185569204,
updated: { base: 1600676032, quote: 0 },
rawRate: { value: 1185569204n, decimals: 9 }
},
{
pair: 'EUR/BTC',
rate: 0.00010899500647220628,
updated: { base: 1600676032, quote: 1600676187 },
rawRate: { value: 108995n, decimals: 9 }
}
]
For each pair, the following information will be returned:
pair
: The base/quote symbol pair stringrate
: The resulting rate of the given pairupdated
: The timestamp at which the base and quote symbols was last updated on BandChain. For USD
, this will be the current timestamprawRate
: This object consists of two parts.
value
is the BigInt
value of the actual rate, multiplied by 10^decimals
decimals
is then the exponent by which rate
was multiplied by to get rawRate