ethcalate-client

Ethcalate creates containerized state channels for dapps. This repository contains the client-side code for installing and using Ethcalate services within your decentralized application.

This repository is designed to be used in conjunction with the Ethcalate Hub and pre-deployed contracts.

Getting Started

Prerequesites

This package is designed for use within a dapp. The package relies on an injected Web3 object from the browser (i.e. MetaMask, which is how the package was developed and tested).

async/await

Most functions in this package return Promises. The preferred way to consume the package is to use async/await syntax.

// React App.js
async componentDidMount () {
  try {
    const ethcalate = new Ethcalate()
    await ethcalate.initContract()
    const myChannels = await ethcalate.getMyChannels()
  } catch (e) {
    console.log(e)
  }
}

Installing

To get started, you can clone this repository or download the Ethcalate package via npm.

npm install ethcalate --save

Instantiating

The client is instantiated to talk to the deployed contract and Hub. The constructor takes one parameter, a web3 instance.

const Ethcalate = require('ethcalate')
const ethcalate = new Ethcalate(web3)

Using the Ethcalate Package

async openChannel({ to, depositInEth, challenge })

This function creates a new bidirectional payment channel between the msg.sender (taken implicitly), and the to address provided. The depositInEth specifies the stake in ETH the sender is willing to put up for the channel, and challenge is the length of the challenge period in seconds.

Note: This is an on-chain transaction, so there will be a transaction confirmation and gas fee.

const to = '0x627306090abab3a6e1400e9345bc60c78a8bef57'
const depositInEth = 1
const challenge = 3600 // 1 hour

await ethcalate.openChannel({ to, depositInEth, challenge })

// MetaMask will pop up to confirm transaction

async joinChannel ({ channelId, depositInEth })

Joins a channel that has been opened with your address as the counterparty address.

Note: This is an on-chain transaction, so there will be a transaction confirmation and gas fee.

const channelId = '0xeb9222432938ac4150ea9c08ccb4ba76b5638b5f27627ae1867305f15050a64f'
const depositInEth = 1

await ethcalate.joinChannel({ channelId, depositInEth })

// MetaMask will pop up to confirm transaction

async updateState ({ channelId, balanceA, balanceB })

Create a signed state update that the counterparty can use to close the channel. balanceA and balanceB are the updated balances of each party in the channel. Balances must be provided in Wei units using the web3.toWei() function.

Note: This is an off-chain transcation so there are NO transaction fees or gas. Hooray!

const channelId = '0xeb9222432938ac4150ea9c08ccb4ba76b5638b5f27627ae1867305f15050a64f'
const balanceA = web3.toWei(0.5, 'ether')
const balanceB = web3.toWei(1.5, 'ether')

await ethcalate.updateState({ channelId, balanceA, balanceB })

// MetaMask will pop up to sign message with your private key, but not send anything to the blockchain

async startChallengePeriod (channelId)

Takes the last countersigned state update, signs it with your private key, and sends it to the blockchain to move the channel to a challenge period.

Note: This is an on-chain transaction, so there will be a transaction confirmation and gas fee.

const channelId = '0xeb9222432938ac4150ea9c08ccb4ba76b5638b5f27627ae1867305f15050a64f'

await ethcalate.startChallengePeriod(channelId)

// MetaMask will pop up twice, first to confirm signature, and second to confirm transaction

async closeChannel (channelId)

Closes channel if the challenge period is over.

Note: This is an on-chain transaction, so there will be a transaction confirmation and gas fee.

const channelId = '0xeb9222432938ac4150ea9c08ccb4ba76b5638b5f27627ae1867305f15050a64f'

await ethcalate.closeChannel(channelId)

// MetaMask will pop up to confirm transaction

async getMyChannels()

Returns all of the channels associated with the msg.sender.

const myChannels = await ethcalate.getMyChannels()
console.log('myChannels: ', myChannels)

async getChannelByAddresses (agentA, agentB)

Returns the channel details of the channel that exists between the provided agentA and agentB addresses.

const channel = await ethcalate.getChannelByAddresses(
  '0xf17f52151ebef6c7334fad080c5704d77216b732', 
  '0x627306090abab3a6e1400e9345bc60c78a8bef57'
)
console.log('channel: ', channel)

async getChannel(id)

Returns a channel given an ID.

const channel = await ethcalate.getChannel('0xeb9222432938ac4150ea9c08ccb4ba76b5638b5f27627ae1867305f15050a64f')
console.log('channel: ', channel)

Contributing

We welcome any contributions and feedback to our code!

To make a contribution, please first open a github issue with a description of the changes that need to be made. Then, submit a pull request referencing the issue.

All pull requests must be based off the master branch.

License

This project is licensed under the MIT License - see the LICENSE.md file for details

Acknowledgments

• Spankchain's General State Channels Repo: https://github.com/nginnever/general-state-channels
• Jehan Tremback's Universal State Channels Repo: https://github.com/jtremback/universal-state-channels