Web 3.0 Blockchain Applications

1. Dapp1 - store

This project is based on this Web3.0 tutorial (https://www.youtube.com/watch?v=Wn_Kb3MR_cU).

This dApp allows users to store the hash code (unique digital fingerprint) of an asset (e.g., images) to the blockchain via an ethereum smart contract.
Note: The image is stored in local server, but its hash code is stored in the blockchain.

2. Dapp2 - trace

This project is modified from the above dApp. We revised the smart contract to add more tracing-related data fields.

3. Dapp3 - NFT

This project is based on this tutorial (https://www.youtube.com/watch?v=GKJBEEXUha0).
Major changes from the original version: 1. use web3.storage to store the image instead of infura ipfs; 2. store a companion json file along with the image file. 3. update to next.js v13.

Preparation

configure hardhat.config.js

1. Copy and paste your private key from metamask (see below)

2. create a dApp on Alchemy (https://www.alchemy.com/)

Note: The dApp is deployed on sepolia / mumbai testnet, not the ethereum / polygon mainnet.

Note: Why we use a 3rd-party node provider, other than use our own node?
By running our own Node we mean that your server stores the entire blockchain. You may choose whether your Node should validate every block of data before adding it to the blockchain (mining, PoW). A Full Node sync can take around a month or two for downloading the whole blockchain. The Light Node sync can take up to several weeks. Hardware requirements to run your own node: At least 2TB of SDD; 4GB Ram; Connected to the internet 24*7. Check this.

Note: Popular 3rd-party node provider comparison (Alchemy vs Infura)

	Alchemy	Infura
Supported Layer 1 networks	Ethereum Mainnet, Solana  Tesnets – Rinkeby, Goerli, Kovan, and the Ropsten network	Ethereum Mainnet   Testnets – Rinkeby, Goerli, Kovan, and the Ropsten network
Supported Layer 2 Network	Polygon, Arbitrum network, and Optimism	Polygon, Arbitrum, Optimism, and the Palm network
Miscellaneous Services	Alchemy Notify, NFT API	IPFS API
Free Plans	300 million compute units per month, for up to 5 applications	100,000 requests per day, for up to 3 different applications   Free 5GB IPFS storage

---

3. Copy and paste the https link.

4. The completed hardhat.config.js file should look like this:

(1) sepolia testnet

require("@nomiclabs/hardhat-waffle");
module.exports = {
  networks: {
    sepolia: {
      url: "https://eth-sepolia.g.alchemy.com/v2/JA5X0KC_sVNPzgVa2lalkbYW0hfq2HOY",
      accounts : ['your prviate key (get from metamask)'],
    }
  }
}

(2) mumbai testnet:

require("@nomiclabs/hardhat-waffle");
module.exports = {
  networks: {
    hardhat: {
      chainId: 80001
    },
    mumbai: {
      url: "https://polygon-mumbai.g.alchemy.com/v2/QI5McvJ5VL2tIX4xDaSoOHpo_c1bG_7e",
      accounts: ['your private key (get from metamask)']
    },
  }
}

(dApp3 only) Create a web3.storage account and get the API key (the API key should be kept secret).

In deploy.js, replace the API key with your own key:

  fs.writeFileSync('./config.js', `export const marketplaceAddress = "${nftMarketplace.address}"
  export const jsonRpcApi = 'https://rpc-mumbai.maticvigil.com'
  
  // Web3Storage_token must be kept secret
  export const Web3Storage_token = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJkaWQ6ZXRocjoweEE5YjFCMzJDYzI3YzJlMWFBNDFGQzg2ZmE1ZUFjRDMyYmNmNDZiNjkiLCJpc3MiOiJ3ZWIzLXN0b3JhZ2UiLCJpYXQiOjE2ODY5MzA3MTI1NTYsIm5hbWUiOiJuZnQifQ.t_pWBYILN8Rkq5HKl51cUhQpNJpvaCjYzu1FpeWrdHA'
  `) 

In this above deploy.js, also specify the mumbai testnet RPC url. It will be used in:

const provider = new ethers.providers.JsonRpcProvider(jsonRpcApi) // otherwise, will use localhost:8545

Setup of dApp1 and dApp2

Write the smart contract

(1) Transaction.sol for dApp1 and dApp2

This contract defines and stores a struct to the blockchain.
In solidity, msg is a global variable in Solidity which handles everything related to the blockchain in the properties that it holds. Right from the gas fees to the amount of ether required to call any function in the smart contract, all of these values are stored inside the msg global variable and can be accessed by using the dot(.) operator.

(2) NFTMarket.sol for dApp3

This contract is much more complex that defines NFT creation and trading.

1. Setup env and compile the contract.

cd smart_contract
npm install 
npm install hardhat @nomiclabs/hardhat-waffle ethereum-waffle chai @nomiclabs/hardhat-ethers ethers @nomiclabs/hardhat-etherscan
npx hardhat help
npx hardhat test
npx hardhat run scripts/deploy.js --network sepolia

    Transactions address: 0xE2DaBD738A3f5F434925d32Ff1e8B4AF3b63Fe94 (copy this to contractAddress in constants.js; each run will differ)

Sensative data that need kept locally:  
    hardhat.config.js (contains private key)

2. copy the Transaction.json file to the client/src/abis folder.

Transaction.json is the ABI (Application Binary Interface) file that defines the smart contract.

3. Copy the contract address to the client/src/constants.js file.

Build the nodejs app.

cd client
npm init vite@latest
npm install tailwindcss react-icons ethers
npm run dev

The dApp needs gas to operate. Get some sepoliaETH from https://faucet.sepolia.com/ (you need to have a sepolia account).

Run prepare_imageset.ipynb to resize and rename images and store them to the ./client/images folder.

Setup of dApp3

First run:

npx create-next-app@latest
npm install hardhat @openzeppelin/contracts npm@nomiclabs/hardhat-waffle ethereum-waffle chai @nomiclabs/hardhat-ethers ethers @nomiclabs/hardhat-etherscan web3.storage

Otherwise:

npm install
npx hardhat test
npx hardhat run scripts/deploy.js --network mumbai

Get some polygon matic tokens from https://mumbaifaucet.com/

npm run dev

Deploy on CentOS + nginx

# curl -sL https://rpm.nodesource.com/setup_16.x | sudo bash -
# sudo yum install -y nodejs

Enter the src folder in server.

sudo npm install
sudo npm run build

Copy /images or /publish (static content folder) to /dist and set the /dist as the website's working folder.
Set the website's php version to static (php not needed).