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efx-api-node

2.0.4 • Public • Published

DeversiFi Trading API Client Library for Node.JS

A Node.JS client for the DeversiFi API

Note, DeversiFi evolved from Ethfinex Trustless, and this client library is due to be replaced at the end of February 2020 with an updated version.

Installation

NPM

  npm i efx-api-node

Prebuild for browser

Alternatively on the browser you can use the standalone build

<script src="http://path/to/dist/efx.js"></script>

Setup

Authentication

Authentication to make all the following requests is done by signing using an Ethereum private key. Signing is handled by the DeversiFi client library if the account is available and unlocked. However if signing using a hardware wallet, or using a raw private key, the message and signature need to be prepared separately.

Pre Requisites

  • An ethereum wallet
  • A web3 provider with your account or a private key
    • Such as MetaMask, keystore file, hardware wallet or raw private key

Instancing

Using MetaMask or a local node

 
// In case of MetaMask make sure you call ethereum.enable() before using it
const EFX = require('efx-api-node')
const efx = await EFX()

Using a remote node

const EFX = require('efx-api-node')
const web3 = new EFX.Web3("https://your-web3-provider")
const efx = await EFX(web3)

Using Infura

const HDWalletProvider = require("truffle-hdwallet-provider");
const Web3 = require("Web3")
 
const privateKey = '8F085...' // Account's private key
const infuraKey = '9e28b...'  // Your Infura API KEY
const infuraURL = 'https://mainnet.infura.io/v3/' + infuraKey
 
const provider = new HDWalletProvider(privateKey, infuraURL)
const web3 = new Web3(provider)
 
efx = await EFX(web3)

View the full example: /examples/node_sell_eth_infura.js

Configuration

It's possible to overwrite values on the configuration on a per instance basis.

The default configuration can be overwriten with an optional parameter userConf when calling the EFX function.

For instance:

  efx = await EFX(web3, {
    api: 'https://your-custom-api-address'
  })

The configuration is also merged with the configuration provided by the exchange on the HTTP endpoint /v1/trading/r/get/conf which at the moment looks similar to this:

"0x":{
    "minOrderTime":300,
    "tokenRegistry":{
      "ETH":{
          "decimals":18,
          "wrapperAddress":"0x965808e7f815cfffd4c018ef2ba4c5a65eba087e",
          "minOrderSize":0.02
      },
      "USD":{
          "decimals":6,
          "wrapperAddress":"0x83e42e6d1ac009285376340ef64bac1c7d106c89",
          "tokenAddress":"0x0736d0c130b2ead47476cc262dbed90d7c4eeabd",
          "minOrderSize":10,
          "settleSpread": 0.002
      }
    },
    "deversifiAddress":"0x9faf5515f177f3a8a845d48c19032b33cc54c09c",
    "exchangeAddress":"0x67799a5e640bc64ca24d3e6813842754e546d7b1",
    "exchangeSymbols":[
      "tETHUSD"
    ]
}

The complete compiled configuration is accessible through efx.config, for instance:

const efx = await EFX()
 
const config = efx.config

Gas Price

You can setup a custom gas price by setting up the 'gasPrice' property

const efx = await EFX()
 
efx.set('gasPrice', web3.utils.toWei('2', 'gwei'))
 

Placing an Order

Before placing an order, you are required to lock tokens into the DeversiFi wrapper contracts. This allows for guaranteed execution and ensures DeversiFi orders can be added directly onto the centralised order book, and matched against trades from centralised users.

Approving Tokens

The first time locking an ERC20 Ethereum-based token from a specific account, you are required to approve it to interact with the time-lock smart contracts.

const token = 'ZRX'
efx.contract.approve(token)

This step does not need to be repeated again, and subsequently you are required only to call the lock function. This transfers tokens into the wrapper token contract, ready to trade.

Locking tokens

const token = 'ZRX'
const amount = 15 // Number of tokens to lock
const forTime = 48 // Time after which unlocking does not require permission
 
const response = await efx.contract.lock(token, amount, forTime)

The time limit specified when locking is a maximum - tokens can always be unlocked after this time limit (in hours) expires. In order to unlock tokens before this expires, you must request a signed permission from DeversiFi.

This is always returned if you have no orders open involving those tokens.

Submitting an order

const symbol = 'ZRXETH'
const amount = -15
const price = 0.0025
 
const orderId = await efx.submitOrder(symbol, amount, price)

Orders are generated and submitted, returning either an orderId or error. A full list of possible errors and their associated explanation is available here.

When submitting this order we use the 3 first parameters:

  • symbol is the pair which you wish to trade
  • amount is specified in the first currency in the symbol (i.e. ZRXETH). For a sell, amount is negative. Amount accepts either maximum 8 d.p, or as many decimals as are available on the relevant token's smart contract if it is fewer than 8.
  • price is specified in the second currency in the symbol (i.e. ZRXETH). Prices should be specified to 5 s.f. maximum.

Warning: DeversiFi orders will always be settled at the exact price you specify, and can never be adjusted by DeversiFi, even if it is at a worse price than the market.

For example, when placing a sell order, if the price specified is below the highest bid available on the order book, the order will be executed instantly at market. However, the amount you receive will reflect only the price that you entered, and not the market price at the time of execution.

The client library also provides methods for submitBuyOrder and submitSellOrder.

You can additionally provide

  • gid - Group ID for your order
  • cid - Client order ID
  • signedOrder - A previously signed order, in case you're handling signing
  • validFor - optional amount of hours this order will be valid for, default to 3600 seconds as specified on the default configuration

Tether market shift

The XXX/USDT markets on DeversiFi build on the liquidity of XXX/USD markets on centralised exchanges. However since there is often not a direct 1:1 rate between USD and USDT, a shift must be applied to the order books.

The configuration for DeversiFi returns a settleSpread parameter:

      "USD":{
          "decimals":6,
          "wrapperAddress":"0x83e42e6d1ac009285376340ef64bac1c7d106c89",
          "tokenAddress":"0x0736d0c130b2ead47476cc262dbed90d7c4eeabd",
          "minOrderSize":10,
          "settleSpread": 0.02
      }

This settleSpread is indicative of the current USDT/USD exchange rate. When orders are placed on USDT markets, the settlement price in the signed order must be shifted by the settleSpread parameter before the order is accepted.

For example, if placing a buy order on the ETH/USD(T) market at a price of 100 USD relative to the centralised exchange the order will be settled on DeversiFi at a price of 102 USDT. Equally a sell order at 100 USD would receive 102 USDT when settled on DeversiFi.

efx.submitOrder(symbol, amount, price) // => settlementPrice = price * (1 + settleSpread)

The settleSpread parameter is set dynamically as a 30 minute rolling mean of the USDT/USD market exchange rate. When placing orders using submitOrder or generating them with createOrder the shift is applied for you.

Cancelling Orders

Cancelling orders requires the orderId you wish to cancel to be signed by the address which created and placed the order.

Standard Cancel

In case you're not signing the requests yourself

await efx.cancelOrder(orderId)

Signing Externally

In case you're signing the requests yourself:

const sig = await efx.sign(parseInt(orderId).toString(16))
const sigConcat = ethUtils.toRpcSig(sig.v, ethUtils.toBuffer(sig.r), ethUtils.toBuffer(sig.s))
 
await efx.cancelOrder(parseInt(orderId), sigConcat)

Account History

If you already have an unlocked wallet available to web3 to use for signing, you can simply get open orders and order history from the API as follows:

// Get all open orders
const openOrders = await efx.getOrders()
 
// Get all historical orders
const historicalOrders = await efx.getOrdersHist()

If an unlocked account is not available to sign with, for example when using a raw private key or hardware wallet, authentication nonce and signature must be pre-signed and passed into the calls. nonce is required to be a timestamp less than 3 hours in the future. signature is the nonce signed using the relevant private key for the address who's orders you wish to view.

const ethUtils = require('ethereumjs-utils')
 
const privKey = /* Your Private Key */
const nonce = ((Date.now() / 1000) + 10800) + ''
 
const hash = ethUtils.hashPersonalMessage(ethUtils.toBuffer(nonce.toString(16)))
const signature = ethUtils.ecsign(hash, privKey)
 
// Get all open orders
const openOrders = await efx.getOrders(null, null, nonce, signature)
 
// Get all historical orders
const historicalOrders = await efx.getOrdersHist(null, null, nonce, signature)

Unlocking tokens

If tokens are not used in active orders they can always be unlocked. If unlocking after the time specified when locking has expired, no permission is required. When unlocking before this, DeversiFi must sign a release permission, after verifying that you have no orders currently active which require that token.

If you need permission the library will automatically call the expected endpoint on DeversiFi API to ask for such permission.

const token = 'ZRX'
const amount = 15
const response = await efx.contract.unlock(token, amount)

When a particular token's lock time has not yet expired, permission is required from DeversiFi to unlock early. This permission can be requested directly from DeversiFi using an API call.

The request must be authenticated using a nonce and signature, and the response contains a signed permission from DeversiFi. This permission will always be granted if DeversiFi is online and your address has no open orders involving those tokens. In case you're signing the requests yourself you could use the following code:

// This example shows how to generate the signature from a raw private key
// Signing using hardware wallets such as Ledger or Trezor can be done using their documentation
 
const ethUtils = require('ethereumjs-utils')
 
const privKey = /* Your Private Key */
const nonce = ((Date.now() / 1000) + 350) + ''
 
const hash = ethUtils.hashPersonalMessage(ethUtils.toBuffer(nonce.toString(16)))
const signature = ethUtils.ecsign(hash, privKey)
 
const response = await efx.contract.unlock(token, amount, nonce, signature)
 
 
const token = 'ZRX'
const amount = 0.001
 
const response = await efx.contract.unlock(token, amount, forTime)
 

More Examples

Aside from these examples, there are complete examples in the examples folder

Submitting a buy order

 
const symbol = 'ETHUSD'
const amount = 1
const price = 100
 
efx.submitOrder(symbol, amount, price)
 

Submitting a sell order

 
const symbol = 'ETHUSD'
const amount = -1
const price = 100
 
const orderId = await efx.submitOrder(symbol, amount, price)
 

Fetching info about specific order

 
const id = 1
 
const order = await efx.getOrder(id)
 

Troubleshooting

A list of error codes returned by the API and reasons are available here. Some more detailed explanations can also be found in the API Documentation.

If you have suggestions to improve this guide or any of the available documentation, please raise an issue on Github, or email info@deversifi.com.

Links

Developing

Setup

  • git clone
  • npm install
  • bash <(curl https://get.parity.io -L) # install parity

Run a node

On kovan:

parity --chain kovan --jsonrpc-apis=all --geth
  • note the jsonrpc set to all
  • note the --geth in order to be compatible with geth's unlock 'duration' parameter

On ropsten:

geth --testnet --fast --bootnodes "enode://20c9ad97c081d63397d7b685a412227a40e23c8bdc6688c6f37e97cfbc22d2b4d1db1510d8f61e6a8866ad7f0e17c02b14182d37ea7c3c8b9c2683aeb6b733a1@52.169.14.227:30303,enode://6ce05930c72abc632c58e2e4324f7c7ea478cec0ed4fa2528982cf34483094e9cbc9216e7aa349691242576d552a2a56aaeae426c5303ded677ce455ba1acd9d@13.84.180.240:30303" --rpc --rpccorsdomain "*" --rpcapi "eth,web3,personal,net"

Alternatively, thanks to ganache-cli we can easily run an eth rpc node emulator. (NOTE: currently tests will fail using ganache)

npm test:rpc

Implementing a new feature

Starting by watching the test files ( you will need a node running )

$ npm run test:watch
  • Write the tests for your new features on the ./test/
  • Add your tests to './test/index.js' file if necessary
  • Create your features on ./src/ folder
  • You will need a ropsten node to do blockchain related tests

Testing

On node.js

$ npm run test

On a headless browser ( using browserify and mochify )

$ npm run test:web

Manually on your browser on a browser console

  • Very useful in case you want to issue commands from Google Chrome while using MetaMask !
$ npm run build:web:run

Building for browers

  • This will build the whole library as one big ugly standalone js file ( uses browserify )
$ npm run build

TODO

  • Allow blockchain tests without relying on a local testnet node by using npm run test:rpc ( ganache ) and deploying mocked contracts at the beginning of the test.

  • Setup Travis-ci to test node.js, browser and standalone build. see this page

License

MIT

Install

npm i efx-api-node

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Version

2.0.4

License

MIT

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