Feb 13
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Learn how to read onchain data from one blockchain to another using Hyperbridge GET requests! In this tutorial, Roy from Polytope Labs shows how to: ✅ Turn a Solidity contract into a HyperApp ✅ Dispatch GET requests to read ERC20 balances on Ethereum Sepolia ✅ Receive and handle cross-chain responses securely ✅ Compute storage slots using the Hyperbridge SDK ✅ Test your contract on testnets with self-relaying Hyperbridge enables trust-minimized cross-chain reads without bridges, oracles, or centralized intermediaries. Perfect for DeFi, gaming, governance, and multi-chain applications. Tools Used: - Solidity + Foundry - Hyperbridge SDK - OpenZeppelin Contracts 🔗 Resources & Links: - Hyperbridge Docs: https://docs.hyperbridge.network - Code in the Video: https://github.com/royvardhan/hyperbridge-get-storage - Join Discord: https://discord.gg/hyperbridge Notes from Roy, the Dev: 1. This tutorial videos show how easily you can determine the storage slot for the data you want, using the Hyperbridge SDK helper functions. But in production, you may have to dynamically generate the target slot of your target contract on the destination chain, in your source contract. This is very common, for examples check how we determine the commitment slot in Intent Gateway contract. 2. You do not need to self relay on the mainnets we support. This video only demonstrates how you can self relay when you are in the testing phase of your contracts. Timestamps / Chapters below so you can jump to the section you need. 0:00 - Introduction: What this tutorial covers 0:06 - Cross-chain GET request overview 0:30 - Project setup: Foundry + Node modules 1:05 - Installing dependencies (Hyperbridge core, Merkle tree, OpenZeppelin) 2:08 - Configuring Foundry to use node_modules 2:58 - Contract skeleton and coding start 3:04 - Turning a contract into a HyperApp 3:36 - Overriding host() function 4:10 - Constructor and host assignment 4:18 - Approving fee token for Hyperbridge 5:21 - Core functionality: GET requests 5:49 - Defining queryTokenBalance function 6:04 - Understanding commitment 6:39 - Constructing DispatchGet: destination, height, keys 9:08 - Setting timeout, fees, context 10:41 - Sending GET request through host 12:02 - Optional: Pay fees via native token 12:48 - Events for dispatch and response 13:57 - Storage mappings for pending commitments 15:07 - Returning commitment and marking pending 15:40 - Implementing onGetResponse 16:42 - Security checks and storage value decoding 19:48 - Marking request as complete 20:42 - Helper function to read stored values 20:47 - Recap: key steps for GET requests 22:03 - Constructing storage slot for ERC20 balance 24:23 - Using Hyperbridge SDK to get height and slot 25:59 - Running tests and using indexer 28:02 - Self-relay workflow on testnet 29:00 - Final tips and example repository #Hyperbridge #Solidity #CrossChain #Web3 #Blockchain #Ethereum #SmartContracts #DeFi #NFTs