Band Protocol

Introduction

Developers building on Opera can now leverage Band Protocol’s decentralized oracle infrastructure. With Band’s oracles, they now have access to various cryptocurrency price data to integrate into their applications.

Supported Tokens

Currently, the list of supported symbols can be found below. Going forward, this list will continue to expand based on developer needs and community feedback.

Crypto
AAVE	BAND	BNB	BTC	COVER
BAND	CREAM	CRV	ETH	FTM
BNB	HEGIC	KP3R	LINK	SFI
BTC	SNX	SUSHI	YFI

Stablecoins
FRAX	USDC	SUSD

Commodities
OIL	XAG	XAU

Forex
CHF	CNY	EUR	GBP	JPY

Price Pairs

The methods in the following sections can work with any combination of base/quote token pairs, as long as the base and quote symbols are supported by the dataset.

Querying Prices

Currently, there are two methods for developers to query prices from Band’s oracle: through Band’s StdReference smart contract on BSC and through their bandchain.js JavaScript helper library.

Solidity Smart Contract

To query prices from Band’s oracle, a smart contract should reference Band’s StdReference contract, specifically the getReferenceData and getReferenceDatabulk methods.

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

Contract Addresses

Blockchain	Contract Address	Explorer
Opera (Mainnet)	0xDA7a001b254CD22e46d3eAB04d937489c93174C3	Link

Example Usage

This contract demonstrates an example of using Band’s StdReference contract and the getReferenceData function.

BandChain.JS

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. It then returns a list of corresponding rate values.

Example Usage

The code below shows an example usage of the function:

const { Client } = require('@bandprotocol/bandchain.js');

// BandChain's REST Endpoint
const endpoint = 'https://rpc.bandchain.org';
const client = new Client(endpoint);

// This example demonstrates how to query price data from
// Band's standard dataset
async function exampleGetReferenceData() {
  const rate = await client.getReferenceData(['BTC/ETH','BAND/EUR', 'FTM/USD']);
  return rate;
}

(async () => {
  console.log(await exampleGetReferenceData());
})();

The corresponding result will then be similar to:

$ node index.js
[ 
    { 
        pair: 'BTC/ETH',
        rate: 30.998744363906173,
        updatedAt: { base: 1615866954, quote: 1615866954 },
        requestID: { base: 2206590, quote: 2206590 } 
    },
    { 
        pair: 'BAND/EUR',
        rate: 10.566138918332376,
        updatedAt: { base: 1615866845, quote: 1615866911 },
        requestID: { base: 2206539, quote: 2206572 } 
    }, 
    { 
        pair: 'FTM/USD',
        rate: 0.36662363,
        updatedAt: { base: 1615866851, quote: 1615866960 },
        requestID: { base: 2206543, quote: 0 } 
    }
]

For each pair, the following information will be returned:

• pair: The base/quote symbol pair string.

• rate: The resulting rate of the given pair.

• updated: The timestamp at which the base and quote symbols were last updated on BandChain. For USD, this will be the current timestamp.

• rawRate: 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.