EmbarkJS-Snark

EmbarkJS-Snark is a convenience library for adding zkSnarks support to your DApp. It's meant to be used as an extension for EmbarkJS, by being added as a property of EmbarkJS, ie EmbarkJS.Snarks.

PLEASE NOTE This is completely alpha software and should not be used in a production environment.

NOTE: This library is meant to be used as a dependency of embark-snark, however it can be used as a standalone library if so desired.

The embarkjs-snark plugin will:

Load the contents of embarkjs-plasma in to the Plasma property of EmbarkJS, so it will available using EmbarkJS.Plasma in your DApp.
Instantiate EmbarkJS.Plasma.

This will expose convenience methods to be used by your DApp to interact with Plasma networks.

Requirements

Embark ^4.1.1

Plugin config

Please see embark-plasma for information on how to set up the embarkjs-plasma plugin to be used in your DApp.

Current limitations and known issues

The plugin currently only supports OMG's Samrong network and v0.2 of the OMG SDK. The root chain is a contract on Rinkeby and the Plasma chain runs on Samrong. Chain creation for development purposes will be added in future versions.
The DApp can use Metamask OR accounts configured in the blockchain config of Embark.

Available properties/functions

embarkjs-plasma exposes functions that are meant to make DApp interaction with Plasma chains easier. The following functions and proeprties are available.

Properties

EmbarkJS.Plasma.currentAddress: the active account exposed by Metamask or the last account configured in the blockchain config. A specific account can be configured setting ROOTCHAIN_ACCOUNT in embark-plasma's plugin config (in embark.json of the DApp). NOTE: this account must be an unlocked node account OR a wallet account configured in blockchain config.

EmbarkJS.Plasma.initing: true when the initialisation routine is in progress (ie run via EmbarkJS.Plasma.init()).

EmbarkJS.Plasma.inited: true when the initialisation routine has finished (ie when EmbarkJS.Plasma.init() has completed).

EmbarkJS.Plasma.config: Object representing the plugin config specified in the DApp's embark.json. See embark-plasma for more config details.

EmbarkJS.Plasma.state: Object that is populated with the current Plasma network information. Could be used for reactive binding on the frontend, however it must be refreshed using EmbarkJS.Plasma.updateState(). Exposes the following:

account.address: String containing current address from Metamask (if used in the DApp).
account.childBalances: Array containing the balances (ETH + ERC20s) of the child account on the child chain
account.rootBalance: Balance of the address on the main chain
transactions: Array of transactions that occurred on the child chain for the account.address.
utxos: UTXOs that exist on the child chain for the account.address.

EmbarkJS.Plasma.rootChain: the omg.js root chain object intialised in EmbarkJS.Plasma.init() using the plugin config.

EmbarkJS.Plasma.childChain: the omg.js child chain object intialised in EmbarkJS.Plasma.init() using the plugin config.

Functions

EmbarkJS.Plasma.balances(): Returns an object containing the balance of the address on the main chain and an array containing the balances (ETH + ERC20s) of the child account on the child chain.

EmbarkJS.Plasma.init(): initialises the root chain and child chain using the plugin configuration. Sets up web3 and gets available accounts (from Metamask if used in the DApp). Refreshes the child chain state.

EmbarkJS.Plasma.deposit(amount, currency = transaction.ETH_CURRENCY, approveDeposit = false): Deposits currency from the main chain in to the Plasma contract and makes the deposit available in a UTXO on the child chain. If using ETH, only the first parameter (amount) is required. approveDeposit should be true when depositing an ERC20. This instructs the the root chain contract to transfer the amount of tokens that you wish to deposit to the contract before depositing them. More information on depositing.

EmbarkJS.Plasma.transfer(toAddress, amount, currency = transaction.ETH_CURRENCY): Transfers currency (ETH or any ERC20) from the main account (active in Metamask if used in DApp context) to any other account on the network. If transferring ETH, the currency parameter can be omitted.

EmbarkJS.Plasma.exitAllUtxos(fromAddress): Exits all UTXO's for the provided address from the child chain to the main chain. Note that exits are subject to the minimum finalisation period (current 7 days). Please see the elixir-omg documentation for more information.

EmbarkJS.Plasma.exitUtxo(from, utxoToExit): Exits the given UTXO for the provided address from the child chain to the main chain. Note that exits are subject to the minimum finalisation period (current 7 days). Please see the elixir-omg documentation for more information.

EmbarkJS.Plasma.selectUtxos(amount, currency): Gets UTXOs for the main account (active in Metamask if in a DApp context) given the provided currency.

EmbarkJS.Plasma.updateState(): Refreshes the state of the Plasma network for the current address (active address if Metamask used), which is available via EmbarkJS.Plasma.state. The following are updated (and available via EmbarkJS.Plasma.state):

account.address: String containing current address from Metamask (if used in the DApp).
account.childBalances: Array containing the balances (ETH + ERC20s) of the child account on the child chain
account.rootBalance: Balance of the address on the main chain
transactions: Array of transactions that occurred on the child chain for the account.address.
utxos: UTXOs that exist on the child chain for the account.address.

Example DApp

The embark-plasma-demo is an example DApp using this plugin. It is based on the OMG js-starter-kit, but instead uses EmbarkJS.Plasma for all its functionality.

emizzle / embarkjs-snark