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* add intro to oracles + current oracles on shimmer article --------- Co-authored-by: Dr-Electron <[email protected]>
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--- | ||
description: 'Learn about the role of in oracles in blockchain,their role in providing external data to smart contracts and the available oracles in Shimmer EVM.' | ||
image: /img/logo/WASP_logo_dark.png | ||
keywords: | ||
- Blockchain Oracles | ||
- Smart Contracts | ||
- Shimmer EVM | ||
- Pyth Network | ||
- Supra Oracles | ||
--- | ||
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# Introduction to Oracles in Blockchain | ||
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Smart contracts are powerful tools in the blockchain ecosystem, enabling automated, self-executing agreements based on | ||
predefined conditions. However, one of their fundamental limitations is that they operate in a sandboxed environment. | ||
This isolation ensures that smart contracts produce the same results every time they run, maintaining the deterministic | ||
nature essential for blockchain's integrity and trust. But this also means smart contracts cannot directly access | ||
or interact with external data or systems. | ||
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## Bridging the Gap with Oracles | ||
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Oracles serve as a critical bridge in this scenario, connecting the isolated world of smart contracts with external data | ||
sources. They play a pivotal role in expanding the functionality of smart contracts by providing them | ||
with real-world information. Oracles fetch data from various external sources, like internet APIs, real-world sensors, | ||
and other data feeds, and then relay this information to the smart contracts on the blockchain. | ||
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### Ensuring Idempotent Results | ||
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The key challenge for oracles in the blockchain context is to provide data with enough specificity and reliability to | ||
guarantee idempotent results - the property that a smart contract will produce the same outcome every time it's executed | ||
under the same conditions. This consistency is crucial for maintaining trust and predictability in the blockchain | ||
environment. | ||
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Oracles achieve this by sourcing data from reliable and verified external sources and using consensus mechanisms or | ||
multiple data points to validate the information's accuracy. This process ensures that the data provided to the smart | ||
contracts is relevant and timely, maintaining the integrity and deterministic nature of the blockchain | ||
operations. | ||
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## Oracles on Shimmer EVM | ||
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### Supra | ||
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Supra Oracles validate and report prices derived from up to 21 data sources with Byzantine Fault Tolerant algorithms | ||
for a wide array of assets and commodities using its own Distributed Oracle Agreement (DORA) to provide data for crypto | ||
prices, forex, equities, and even Web3 data from other blockchains. Its feed gets updated from a minimum of 3 to 8 sources; if a data pair fails to meet this criterion, it gets deprecated to ensure data reliability. | ||
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:::tip | ||
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You can learn more about Supra Oracles in their [official documentation](https://supraoracles.com/docs/overview). | ||
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::: | ||
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### Pyth | ||
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The Pyth Network delivers real-time financial market data across multiple blockchains and can be used in off-chain applications. | ||
Pyth gets contributions from over 90 publishers, including several exchanges. It offers comprehensive and accurate price | ||
feeds for asset classes such as US equities, commodities, and cryptocurrencies. Its price feeds get updates | ||
multiple times per second, ensuring they are current and reliable. | ||
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:::tip | ||
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You can learn more about Pyth Oracles in their [official documentation](https://docs.pyth.network/documentation). | ||
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::: | ||
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#### Example Code | ||
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You can use the following example code to get data from Pyth Oracles in Shimmer EVM: | ||
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```typescript | ||
import {ethers} from "ethers"; | ||
import fetch from "node-fetch"; | ||
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// Provider | ||
const providerURL = "https://json-rpc.evm.shimmer.network" | ||
const provider = new ethers.JsonRpcProvider(providerURL); | ||
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// Pyth Oracle contract on ShimmerEVM Mainnet | ||
const contractAddress = '0xA2aa501b19aff244D90cc15a4Cf739D2725B5729'; | ||
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// Add Price Feed Ids obtained from https://pyth.network/developers/price-feed-ids#pyth-evm-stable | ||
const priceFeedIds = [ | ||
//SMR/USD | ||
'0xaf5b9ac426ae79591fde6816bc3f043b5e06d5e442f52112f76249320df22449', | ||
//BTC/USD | ||
'0xe62df6c8b4a85fe1a67db44dc12de5db330f7ac66b72dc658afedf0f4a415b43' | ||
] | ||
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async function getPrice() { | ||
// Replace 'IPythJSONURL' with the actual URL where the IPyth ABI JSON is hosted | ||
const pythAbiUrl = 'https://raw.githubusercontent.com/pyth-network/pyth-sdk-solidity/main/abis/IPyth.json'; | ||
const pythAbi = await fetch(pythAbiUrl).then((response) => response.json()); | ||
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const pythContract = new ethers.Contract(contractAddress, pythAbi, provider); | ||
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try { | ||
for (const priceFeedId of priceFeedIds) { | ||
const priceData = await pythContract.getPrice(priceFeedId); | ||
const price = Number(priceData.price) * 10 ** (Number(priceData.expo)); | ||
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console.log(`Price for ${priceFeedId}:`); | ||
console.log('Price:', price); | ||
console.log('Confidence Interval:', priceData.conf.toString()); | ||
// Convert publishTime to a formatted date | ||
const publishTimeDate = new Date(Number(priceData.publishTime) * 1000); | ||
console.log('Publish Time:', publishTimeDate.toUTCString()); | ||
console.log('\n'); | ||
} | ||
} catch (error) { | ||
console.error('Error:', error.message); | ||
} | ||
} | ||
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async function main() { | ||
try { | ||
await getPrice(); | ||
} catch (error) { | ||
console.error('Main Error:', error.message); | ||
} | ||
} | ||
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main(); |
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