이더리움 - Web.js

Web3.js tutorial

• 스마트 컨트랙트 개발
• → solidity를 통한 개발

• 블록체인과 상호작용하는 웹사이트 또는 클라이언트 개발
• → web3.js를 통해 이더리움과 상호작용하는 클라이언트를 개발할 수 있다.
• 계정간의 이더 전송
• 스마트 컨트랙트에서 데이터 R/W
• web3.js → JSON RPC → EVM network
 

Install

npm install web3

• Geth와 같은 자체 이더리움 노드를 실행할 수 있지만, 블록체인의 많은 데이터를 다운로드 하고 동기화를 유지하여야 한다.
• 그래서, 편의를 위해 Infura를 통한 이더리옴 노드 엑세스를 한다.

Infura

• 원격 이더리움 노드를 무료로 제공하는 서비스, 원격 이더리움에 접근할 수 있도록 엔드포인트 제공

• api key
• https://mainnet.infura.io/6ece1a163c6642c89b7dae9ebec4af93

• 계좌 잔액 확인

const {Web3} = require('web3')

async function getBalance(){
    const rpcURL = "https://mainnet.infura.io/v3/6ece1a163c6642c89b7dae9ebec4af93"
    const web3 = new Web3(rpcURL);
    const address = "0x90e63c3d53E0Ea496845b7a03ec7548B70014A91"
    let balance=await web3.eth.getBalance(address);
    console.log(balance)
}

getBalance();

// result
0n

• totalSupply, name, symbol, balanceof 확인

async function readContractData() {
    const address = "0xd26114cd6EE289AccF82350c8d8487fedB8A0C07"
    const abi = [{"constant":true,"inputs":[],"name":"mintingFinished","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"unpause","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_amount","type":"uint256"}],"name":"mint","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"paused","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"finishMinting","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"pause","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_amount","type":"uint256"},{"name":"_releaseTime","type":"uint256"}],"name":"mintTimelocked","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"payable":false,"type":"function"},{"anonymous":false,"inputs":[{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Mint","type":"event"},{"anonymous":false,"inputs":[],"name":"MintFinished","type":"event"},{"anonymous":false,"inputs":[],"name":"Pause","type":"event"},{"anonymous":false,"inputs":[],"name":"Unpause","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"}];
    const contract = new web3.eth.Contract(abi, address)
    let totalSupply = await contract.methods.totalSupply().call((err, result) => { console.log(result) })
    let name = await contract.methods.name().call((err, result) => { console.log(result) })
    let symbol = await contract.methods.symbol().call((err, result) => { console.log(result) })
    let balanceof = await contract.methods.balanceOf('0xd26114cd6EE289AccF82350c8d8487fedB8A0C07').call((err, result) => { console.log(result) })
    console.log("Total Supply: ", totalSupply)
    console.log("Name: ", name)
    console.log("Symbol: ", symbol)
    console.log("Balance of: ", balanceof)
}

// result
Total Supply:  140245398245132780789239631n
Name:  OMGToken
Symbol:  OMG
Balance of:  30361262360212023356200n

• 이더리움 블록체인 트랜잭션 작동 방식
• 네트워크에 트랜잭션을 브로드캐스트 하려면, 먼저 서명을 해야 한다.
• 원격 노드의 서명을 진행하기 위해, 다음 라이브러리를 설치한다.
npm install ethereumjs-tx
• ropsten 테스트넷 address를 2개 생성한다.

async function createAddress() {
    const ropsten_web3 = new Web3('https://ropsten.infura.io/6ece1a163c6642c89b7dae9ebec4af93')
    let address = await ropsten_web3.eth.accounts.create()
    console.log(address)
}
// result (2번 실행)
{
  address: '0x9375B6a317983c97f39BF525abC139ADC3972Fae',
  privateKey: '0x5c97327b1852d322cc73c26f6cb9ffbcfc493acd025ad4377f49108c504dca00',
  signTransaction: [Function: signTransaction],
  sign: [Function: sign],
  encrypt: [Function: encrypt]
}
{
  address: '0xD2eea25e6076d37A10615EE597D92010BD84D609',
  privateKey: '0xc3164799ad088ffa124f853c1c91471f1ab610dfec6d25256e96be8e5074cd0c',
  signTransaction: [Function: signTransaction],
  sign: [Function: sign],
  encrypt: [Function: encrypt]
}