dex-server

README

DEX backend

Official decentralized exchange backend, forked from the Proof project.
Support deposit scenarios: coin-coin, token-coin, token-token.
The matching-engine will be soon moved to blockchain services.

Getting Started

Requirements

• mongoDB version 3.6 or newer
• rabbitmq version 3.7.7 or newer
• dep latest

Deployment guide step by step

https://github.com/tomochain/dex-smart-contract/blob/develop/Deployment_step_by_step.md

REST API

See REST_API.md

Websocket API

See WEBSOCKET_API.md

Types

Orders

Orders contain the information that is required to register an order in the orderbook as a "Maker".

• id is the primary ID of the order (possibly deprecated)
• orderType is either BUY or SELL. It is currently not parsed by the server and compute directly from buyToken, sellToken, buyAmount, sellAmount
• exchangeAddress is the exchange smart contract address
• maker is the maker (usually sender) ethereum account address
• buyToken is the BUY token ethereum address
• sellToken is the SELL token ethereum address
• buyAmount is the BUY amount (in BUY_TOKEN units)
• sellAmount is the SELL amount (in SELL_TOKEN units)
• expires is the order expiration timestamp
• nonce is the nonce that corresponds to
• feeMake is the maker fee (not implemented yet)
• feeTake is the taker fee (not implemented yet)
• pairID is a hash of the corresponding
• hash is a hash of the order details (see details below)
• signature is a signature of the order hash. The signer must equal to the maker address for the order to be valid.
• price corresponds to the pricepoint computed by the matching engine (not parsed)
• amount corresponds to the amount computed by the matching engine (not parsed)

Order Price and Amount

There are two ways to describe the amount of tokens being bought/sold. The smart-contract requires (buyToken, sellToken, buyAmount, sellAmount) while the orderbook requires (pairID, amount, price).

The conversion between both systems can be found in the engine.ComputeOrderPrice function

Order Hash

The order hash is a sha-256 hash of the following elements:

• Exchange address
• Token Buy address
• Amount Buy
• Token Sell Address
• Amount Sell
• Expires
• Nonce
• Maker Address

Trades

When an order matches another order in the orderbook, the "taker" is required to sign a trade object that matches an order.

• orderHash is the hash of the matching order
• amount is the amount of tokens that will be traded
• trade nonce is a unique integer to distinguish successive but identical orders (note: can probably be renamed to nonce)
• taker is the taker ethereum account address
• pairID is a hash identifying the token pair that will be traded
• hash is a unique identifier hash of the trade details (see details below)
• signature is a signature of the trade hash

Trade Hash:

The trade hash is a sha-256 hash of the following elements:

• Order Hash
• Amount
• Taker Address
• Trade Nonce

The (Order, Trade) tuple can then be used to perform an on-chain transaction for this trade.

Quote Tokens and Token Pairs

In the same way as traditional exchanges function with the idea of base currencies and quote currencies, the decentralized exchange works with base tokens and quote tokens under the following principles:

• Only the exchange operator can register a quote token
• Anybody can register a token pair (but the quote token needs to be registered)

Token pairs are identified by an ID (a hash of both token addresses)