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| 1 | +import { Callout, Tabs } from "nextra/components"; |
| 2 | + |
| 3 | +# How to Use Real-Time Data in IOTA Contracts |
| 4 | + |
| 5 | +This guide explains how to use real-time Pyth data in IOTA applications. |
| 6 | + |
| 7 | +## Install Pyth SDK |
| 8 | + |
| 9 | +Use the following dependency in your `Move.toml` file to use the latest Pyth IOTA package and its dependencies: |
| 10 | + |
| 11 | +<Tabs items={['IOTA Testnet']}> |
| 12 | +<Tabs.Tab> |
| 13 | + |
| 14 | +```sh copy |
| 15 | +[dependencies.Pyth] |
| 16 | +git = "https://github.com/pyth-network/pyth-crosschain.git" |
| 17 | +subdir = "target_chains/iota/contracts" |
| 18 | +rev = "iota-contract-testnet" |
| 19 | + |
| 20 | +[dependencies.Wormhole] |
| 21 | +git = "https://github.com/pyth-network/pyth-crosschain.git" |
| 22 | +subdir = "target_chains/iota/contracts/vendor/wormhole_iota_testnet/wormhole" |
| 23 | +rev = "iota-contract-testnet" |
| 24 | + |
| 25 | +[dependencies.Iota] |
| 26 | +git = "https://github.com/iotaledger/iota.git" |
| 27 | +subdir = "crates/iota-framework/packages/iota-framework" |
| 28 | +rev = "develop" |
| 29 | +``` |
| 30 | + |
| 31 | +</Tabs.Tab> |
| 32 | +</Tabs> |
| 33 | + |
| 34 | +Pyth also provides a javascript SDK to construct transaction blocks that update price feeds: |
| 35 | + |
| 36 | +<Tabs items={["IOTA"]}> |
| 37 | + <Tabs.Tab> |
| 38 | + ```sh |
| 39 | + # NPM |
| 40 | + npm install --save @pythnetwork/pyth-iota-js |
| 41 | + |
| 42 | + # Yarn |
| 43 | + yarn add @pythnetwork/pyth-iota-js |
| 44 | + ``` |
| 45 | + |
| 46 | + </Tabs.Tab> |
| 47 | +</Tabs> |
| 48 | + |
| 49 | +## Write Contract Code |
| 50 | + |
| 51 | +The code snippet below provides a general template for what your contract code should look like: |
| 52 | + |
| 53 | +```rust {18} copy |
| 54 | +module pyth_example::main { |
| 55 | + use iota::clock::Clock; |
| 56 | + use pyth::price_info; |
| 57 | + use pyth::price_identifier; |
| 58 | + use pyth::price; |
| 59 | + use pyth::pyth; |
| 60 | + use pyth::price_info::PriceInfoObject; |
| 61 | + |
| 62 | + const E_INVALID_ID: u64 = 1; |
| 63 | + |
| 64 | + public fun use_pyth_price( |
| 65 | + // Other arguments |
| 66 | + clock: &Clock, |
| 67 | + price_info_object: &PriceInfoObject, |
| 68 | + ){ |
| 69 | + let max_age = 60; |
| 70 | + // Make sure the price is not older than max_age seconds |
| 71 | + let price_struct = pyth::get_price_no_older_than(price_info_object,clock, max_age); |
| 72 | + |
| 73 | + // Check the price feed ID |
| 74 | + let price_info = price_info::get_price_info_from_price_info_object(price_info_object); |
| 75 | + let price_id = price_identifier::get_bytes(&price_info::get_price_identifier(&price_info)); |
| 76 | + |
| 77 | + // ETH/USD price feed ID |
| 78 | + // The complete list of feed IDs is available at https://pyth.network/developers/price-feed-ids |
| 79 | + // Note: IOTA uses the Pyth price feed ID without the `0x` prefix. |
| 80 | + assert!(price_id!=x"ff61491a931112ddf1bd8147cd1b641375f79f5825126d665480874634fd0ace", E_INVALID_ID); |
| 81 | + |
| 82 | + // Extract the price, decimal, and timestamp from the price struct and use them |
| 83 | + let decimal_i64 = price::get_expo(&price_struct); |
| 84 | + let price_i64 = price::get_price(&price_struct); |
| 85 | + let timestamp_sec = price::get_timestamp(&price_struct); |
| 86 | + } |
| 87 | +} |
| 88 | +``` |
| 89 | + |
| 90 | +One can consume the price by calling `pyth::get_price` abovementioned or other utility functions on the `PriceInfoObject` in the Move module |
| 91 | + |
| 92 | +The code snippet below provides an example of how to update the Pyth price feeds: |
| 93 | + |
| 94 | +```ts copy |
| 95 | +import { IotaPriceServiceConnection, IotaPythClient } from "@pythnetwork/pyth-iota-js"; |
| 96 | +import { Transaction } from "@iota/iota-sdk/transactions"; |
| 97 | + |
| 98 | +// Get the Stable Hermes service URL from https://docs.pyth.network/price-feeds/api-instances-and-providers/hermes |
| 99 | +const connection = new IotaPriceServiceConnection("https://hermes-beta.pyth.network"); |
| 100 | + |
| 101 | +const priceIDs = [ |
| 102 | + // You can find the IDs of prices at https://pyth.network/developers/price-feed-ids |
| 103 | + "0xe62df6c8b4a85fe1a67db44dc12de5db330f7ac66b72dc658afedf0f4a415b43", // BTC/USD price ID |
| 104 | + "0xff61491a931112ddf1bd8147cd1b641375f79f5825126d665480874634fd0ace", // ETH/USD price ID |
| 105 | +]; |
| 106 | + |
| 107 | +const priceUpdateData = await connection.getPriceFeedsUpdateData(priceIDs); |
| 108 | + |
| 109 | +// It is either injected from the browser or instantiated in the backend via some private key |
| 110 | +const wallet: SignerWithProvider = getWallet(); |
| 111 | +// Get the state IDs of the Pyth and Wormhole contracts from |
| 112 | +// https://docs.pyth.network/price-feeds/contract-addresses/iota |
| 113 | +const wormholeStateId = "0x5306f64e312b581766351c07af79c72fcb1cd25147157fdc2f8ad76de9a3fb6a"; |
| 114 | +const pythStateId = "0x1f9310238ee9298fb703c3419030b35b22bb1cc37113e3bb5007c99aec79e5b8"; |
| 115 | + |
| 116 | +const client = new IotaPythClient(wallet.provider, pythStateId, wormholeStateId); |
| 117 | +const tx = new Transaction(); |
| 118 | +const priceInfoObjectIds = await client.updatePriceFeeds(tx, priceFeedUpdateData, priceIDs); |
| 119 | + |
| 120 | +tx.moveCall({ |
| 121 | + target: `pyth_example::main::use_pyth_price`, |
| 122 | + arguments: [ |
| 123 | + ..., // other arguments needed for your contract |
| 124 | + tx.object(priceInfoObjectIds[0]), |
| 125 | + ], |
| 126 | +}); |
| 127 | + |
| 128 | +const txBlock = { |
| 129 | + transactionBlock: tx, |
| 130 | + options: { |
| 131 | + showEffects: true, |
| 132 | + showEvents: true, |
| 133 | + }, |
| 134 | +}; |
| 135 | + |
| 136 | +const result = await wallet.signAndExecuteTransactionBlock(txBlock); |
| 137 | +``` |
| 138 | + |
| 139 | +By calling the `updatePriceFeeds` function, the `IotaPythClient` adds the necessary transactions to the transaction block to update the price feeds. |
| 140 | + |
| 141 | +<Callout type="warning" emoji="⚠️"> |
| 142 | + |
| 143 | +Your IOTA Move module **should NOT** have a hard-coded call to `pyth::update_single_price_feed.` In other words, a contract should **never call** the IOTA Pyth `pyth::update_single_price_feed` entry point. Instead, it should be called directly from client code (e.g., Typescript or Rust). |
| 144 | + |
| 145 | +When IOTA contracts are [upgraded](<(https://docs.IOTA.io/build/package-upgrades)>), the address changes, which makes the old address no longer valid. If your module has a hard-coded call to `pyth::update_single_price_feed` living at a fixed call-site, it may eventually get bricked due to how Pyth upgrades are implemented. (Pyth only allow users to interact with the most recent package version for security reasons). |
| 146 | + |
| 147 | +Therefore, you should build a [IOTA programmable transaction](https://docs.IOTA.io/build/prog-trans-ts-sdk) that first updates the price by calling `pyth::update_single_price_feed` at the latest call-site from the client-side and then call a function in your contract that invokes `pyth::get_price` on the `PriceInfoObject` to get the recently updated price. |
| 148 | +You can use `IOTAPythClient` to build such transactions and handle all the complexity of updating the price feeds. |
| 149 | + |
| 150 | +Consult [Fetch Price Updates](../fetch-price-updates) for more information on how to fetch the `pyth_price_update`. |
| 151 | + |
| 152 | +</Callout> |
| 153 | + |
| 154 | +## Additional Resources |
| 155 | + |
| 156 | +You may find these additional resources helpful for developing your IOTA application. |
| 157 | + |
| 158 | +### CLI Example |
| 159 | + |
| 160 | +[This example](https://github.com/pyth-network/pyth-crosschain/tree/main/target_chains/iota/cli) shows how to update prices on a IOTA network. It does the following: |
| 161 | + |
| 162 | +1. Fetches update data from Hermes for the given price feeds. |
| 163 | +1. Call the Pyth IOTA contract with a price update. |
| 164 | + |
| 165 | +You can run this example with `npm run example-relay`. A full command that updates prices on the IOTA testnet looks like this: |
| 166 | + |
| 167 | +```bash |
| 168 | +export IOTA_KEY=YOUR_PRIV_KEY; |
| 169 | +npm run example-relay -- --feed-id "5a035d5440f5c163069af66062bac6c79377bf88396fa27e6067bfca8096d280" \ |
| 170 | +--hermes "https://hermes-beta.pyth.network" \ |
| 171 | +--full-node "https://fullnode.testnet.IOTA.io:443" \ |
| 172 | +--pyth-state-id "0xd3e79c2c083b934e78b3bd58a490ec6b092561954da6e7322e1e2b3c8abfddc0" \ |
| 173 | +--wormhole-state-id "0x31358d198147da50db32eda2562951d53973a0c0ad5ed738e9b17d88b213d790" |
| 174 | +``` |
| 175 | + |
| 176 | +### Contract Addresses |
| 177 | + |
| 178 | +Consult [IOTA Contract Addresses](../contract-addresses/iota) to find the package IDs. |
| 179 | + |
| 180 | +### Pyth Price Feed IDs |
| 181 | + |
| 182 | +Consult [Pyth Price Feed IDs](https://pyth.network/developers/price-feed-ids) to find Pyth price feed IDs for various assets. |
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