Agora

A full-stack Dapp framework consisting of a React front-end running on NodeJS that interacts with a solidity smart contract deployed to an etherium-compatible blockchain.

Framework for Web3 Applications

This sample application models an online marketplace where a user can connect a metamask wallet to buy & sell audio NFTs.

Tech Stack

• NodeJS : javascript runtime (backend) Version 16.14.2
• React : front-end component-based framework
• Ethers.js : Etherium Blockchain library https://docs.ethers.io
• Solidity : smart contract programming
  • https://www.theengineeringprojects.com/2021/06/what-is-solidity-programming.html
  • https://www.bitdegree.org/learn/solidity-examples
• OpenZeppelin : Solidity lib for Etherium Smart Contracts https://docs.openzeppelin.com/contracts/4.x/
• HardHat.org Version: 2.9.3
  • Etherium local development environment https://hardhat.org/getting-started/#installation
• SAMPLE DATA
  • IPFS : create initial NFT metadata file(.car) from JSON metadata https://car.ipfs.io
  • NFT.storage : store NFT metadata in .car files. https://NFT.storage/new-file/
    • Create a new account and login to upload metadata files
    • Creates URI address accessed by smart contract code

INSTALLATION

• Read Here: INSTALLATION.md

Development Workflow

Launch a local blockchain node

Hardhat

• Start a local ethereum node : cd to project directory (location of hardhat.config.js) and launch a hardhat node for testing

  $ cd dev/github/blockchain101/agora

  $ npx hardhat node

• Must be running a version of nodeJS supported by Hardhat

• Smart Contracts/Tokens must be deployed to the blockchain using deploy.js before launching the application

  $ cd src\backend\scripts

  $npm run deploy

• Hardhat javascript console

  $ npx hardhat console --network localhost

Smart Contract development workflow

• Modify smart contract code in src/contracts/main_contract.sol
• Run Unit tests & check for errors

  $ npx hardhat test

• If not already there, add smart contract to deploy.js . Location is commented.
• Compile & deploy to executing hardhat blockchain process. (deploy.js)

  $ npm run src/back/scripts/deploy

• src/back/scripts/deploy.js contains the code for deploying the smart contract to the Hardhat blockchain node.
• deploys using first demo wallet account
• Note Smart contract address for next step
• Verify deployment using hardhat console

  $ npx hardhat console --network localhost
  ~> const contract = await ethers.getContractAt(".sol contract name","smart contract address")

• To deploy on Rinkeby testnet : https://www.scien.cx/2021/09/17/how-to-deploy-a-smart-contract-to-rinkeby-testnet-using-infura-and-hardhat/

Start the Application

• NodeJS must be installed and running
• From the application directory

  $ npm run start

Sample Application Data

• IPFS : create initial NFT metadata file(.car) from JSON metadata https://car.ipfs.io
• NFT.storage : store NFT metadata in .car files. https://app.nft.storage/login
  • Create a new account and login to upload metadata files
  • Creates URI address accessed by smart contract code
• src/backend/scripts/deploy.js contains the code for deploying the smart contract to the Hardhat blockchain node.