# Zenlink

## Project Overview

Based on the prediction of the further growth of the DEX ecosystem in the future and the rapid development of the public blockchain technology, we propose a Polkadot network-based, high-liquidity, cross-chain DEX Network, Zenlink.
  
## Project Details

### System Components

In general, Zenlink project consists of the following parts:
- Zenlink DEX Protocol: The top-level unified general DEX protocol.
- Zenlink DEX Module: Polkadot Network Module implemented according to the Zenlink Protocol standard. We prefer to make it to have Auto Market Maker(AMM) function and be easy imported into parachain in multiple ways.
- Zenlink DEX Aggregator: A simple and user-friendly entrance of DEX world which is able to connect with most of DEX on Polkadot, so that user can do one-click trade with multiple DEX on low slippage
- Zenlink Token(ZLK): The native token of Zenlink DEX Protocol which can be used to distribute liquidity benefits and governance, etc
- Zenlink DEX Network: A decentralized exchange network composed of Zenlink DEX Module, Zenlink DEX Aggregator and other DEX Application on parachains.

![Zenlink Ecosystem](https://images-cdn.shimo.im/TrQlWEFKIz34Mv54__thumbnail.png)

### The whole planning of Zenlink

Firstly, Zenlink DEX Module will be implemented based on Zenlink DEX Protocol. In order to complete the Zenlink ecosystem, we would like to deploy it to a substrate blockchain and build a front-end website application, Zenlink DEX Dapp, for test.

Secondly, we would like to build another important component, Zenlink DEX Aggregator. It will connect to Zenlink DEX Dapp.

Thirdly, we will test the full function of Zenlink DEX Module and Aggregator on Kusama. Users also can try it on Zenlink DEX Dapp.

Finally, the whole infrastructure(Zenlink DEX Module and Aggregator) will be deployed to Polkadot, so that Zenlink DEX Dapp will be switched to Polkadot network and published.

![Zenlink Architecture](https://uploader.shimo.im/f/aCpI4JDF0fHIhpjw.png!thumbnail)

## What we will implement in this grant
We will only build prototypes of basic components in this grant because the whole project is too large to be implemented in only one grant.

In this grant, the functional prototypes, Zenlink DEX Module and Protocol, will be validated on a substrate chain. If it works, there will be only a small effect to migrate those components to the better test network, Kusama.

Besides, we will build a user interface website, Zenlink DEX Dapp, which would connect to the substrate chain and allow testers to try the basic function, such as creating trading pair, displaying price and swapping token etc.

The purpose of this grant is that verification function prototype and test user interface in lean way.

## Technical specifications and design

### Architecture

The ZenLink DEX Protocol defines several classes including Factory, Swap, and Balance. Here is the basic function description, using the ABC/DOT trading pair as an example.

#### Class Factory 
Factory is the core module of ZenLink Dex Protocal. Factory ACTS as a registry. Each token trading pair creates its own pool of liquidity through The Factory. When a liquidity pool is established, initial funds are deposited in it to provide liquidity.

**Functions**
* createPool(ABC, ABC amount, DOT, DOT amount): creating liquitidy pool.
* initPair(ABC, ABC amount, DOT, DOT amount): initializing liquitidy pool. The initial state of the liquidity pool is recorded in storage and a unique index is marked for each liquidity pool.

#### Class Swap
Swap provides a exposed RPC interface for the user to accept transactions and extract liquidity from the user.

**Functions***
* trade(ABC, ABC amount, DOT): Public interface. This is used to accept a trading request from the user.
* rebalance(ABC, ABC amount, DOT, DOT amount): Modify the asset status of the liquidity pool. This is the only entry function to modify the liquidity pool.
* deposit(ABC, ABC amount, DOT, DOT amount):  Public interface. This is used to accept a  request which deposit assets into liquidity pool from the user.
* transfer(user address, DOT, DOT amount): Transfer assets to an user address from a liquidity pool.
* withdraw(ABC, ABC amount, DOT, DOT amount):  Public interface. This is used to accept a  request which withdraw assets from liquidity pool from the user.
* withdrawTransfer(user address, ABC, ABC amount, DOT, DOT amount): Dedicated transfer function fro withdraw action.

#### Class Balance
Balance maintains the core function of AMM, that is, defining the liquidity constant function used throughout the protocol. Therefore, Balance provides basic liquidity calculation functions for other classes of the protocol, such as initial liquidity calculation, transaction calculation, etc. 
In addition, Balance provides the exposed RPC interface to the user. Users can query all liquidity pools that have been created and the supply of a liquidity pool.

**Functions**
- initPoolCalculate(ABC, DOT): Calculating the assets status a liquidity pool while initializing.
- tradeCalculate(ABC, ABC amount, DOT): Calculatiing trading amount for a pair.
- depositCalculate(ABC, ABC amount, DOT, DOT amount): Calculating the assets status a liquidity pool while depositing.
- withdrawCalculate(ABC, ABC amount, DOT, DOT amount): Calculating the assets status a liquidity pool while withdrawing.
- of(ABC, DOT): Query the asset status of the liquidity pool.

### The class diagram
Based on some user scenarios, we will outline how classes in the protocol are called to each other.

#### Creating liquidity pool
![Creating liquidity pool](https://uploader.shimo.im/f/SwOhaOAWxj6mp8WH.png!thumbnail)
When user want to create a liquidity pool, the transaction with ABC and DOT would call the function createPool which exposes the public interfaces externally and belongs to class Factory.  Then, the function initPoolCalculate of class Balance would be in charge of the assets status estimation. After that, the function initPair of class Factory will new a pair instance.

#### Deposit
![deposit](https://uploader.shimo.im/f/L7uWfWpPSb3CJmck.png!thumbnail)
The function deposit of class Swap is exposed to public, user can call it via RPC interface. The function despositCalculate of class Balance would give the correct amount of ABC and DOT which is required by the contant fucntion in the protocal. Then, the asset status would be changed by the function rebalance of class Swap.

#### Trading
![deposit](https://uploader.shimo.im/f/sj2jkCdzEbOZIhLL.png!thumbnail)
When the user want to trade with a liquidity pool, the transaction with ABC would call the function trade which exposes the public interfaces externally and belongs to class Swap.  Then, the function tradeCalculate and rebalance of class Balance would be in charge of the assets status estimation and modify. After that, the function transfer of class Swap will send DOT to the user.

#### Withdraw
![deposit](https://uploader.shimo.im/f/wuVnVMZkr9E7NUAp.png!thumbnail)
The function withdraw of class Swap is exposed to public, user can call it via RPC interface. The function withdrawCalculate of class Balance would give the correct amount of ABC and DOT which can be withdrawn from the liquidity pool. Then, the asset status would be changed by the function rebalance of class Swap, so that the user would receive ABC and DOT by the function withdrawTransfer.

## Ecosystem Fit 
No.

## Team members
* Guo hui(Leo Guo), team leader
* Tianling, principal blockchain expert

## Team Website	
* https://zenlink.pro/

## Legal Structure 
The team has no legal entity now, however, we are planning to build a foundation in Singapore. 

## Team's experience
The team is made up of many experienced professionals in the blockchain industry.  

Guo hui(Leo Guo) is the project leader. He joined imToken very early (June 2017) and worked for 3 years as a data analyst and marketing operation specialist. He is very good at trading quotes and user data analysis which helps imToken get 10m users and Tokenlon, imToken’s DEX, achieve 600m trading volume as well.

Tianling was a former senior expert of Alibaba. After leaving it, he joined a blockchain company as the core developer for 3 years. He is familiar with the underlying blockchain design and substrate development and also was in charge of the architecture design. Now, he is the principal blockchain expert of Zenlink team.

Besides, two core team members are joining us. One of the potential candidates has rich experience in product design and management. He has built a nice and user-friendly DEX application. And the other one is a senior front-end dev with 5 years experience, and he will help us build the first DEX web application.

## Team Code Repos
* https://github.com/zenlinkpro

## Team LinkedIn Profiles
No

## Development Roadmap

### Milestone 1 — Implementing Zenlink DEX Module — 1 month — $8,000

Generally, we would like to verify the product prototype in a specific environment.
* We will deliver Zenlink DEX Module on a substrate blockchain.
* It will has Automate Market Maker(AMM) function.

| Deliverable  | Specification  | 
|--------------|---------------|
| Zenlink DEX Module Repository | A git repository containing the dex module source code and a README that describes the work done during this milestone and how to use set up and run at the current stage |
| Tests        | The code will have proper unit-test coverage to ensure functionality and robustness                                                                    | 
| Docker       | Docker image with a Substrate chain using our module, demonstrating its functionality                                                                  | 

### Milestone 2 — Implementing Zenlink DEX Dapp — 1 month — $10,000
Generally, we would like to build an user interface to test and verify the user experience and dex functionality in a specific environment.
* We will implement Zenlink DEX DApp production prototype and ui design.
* We will deliver a DEX Dapp, Zenlink DEX Dapp.
* It will be connect with the above substrate blockchain.
* Testers will be able to try the basic function, such as creating trading pair, displaying price and swapping token etc.

| Deliverable  | Specification | 
|--------------|---------------|
| Zenlink DEX Module Repository | A git repository containing **the dex module** source code and a README that describes the work done during this milestone and how to use set up and run at the current stage |
| Zenlink DEX Dapp Repository | A git repository containing **the dex dapp** source code and a README that describes the work done during this milestone and how to use set up and run at the current stage |
| Tests        | The code will have proper unit-test coverage to ensure functionality of the trading business and robustness                                             | 
| Docker       | Docker image with a Substrate chain using our module and dapp which can demonstrate functionality via web browser at a local machine              | 

## Future Plans
* Migrate the above basic components to Kusama for test
* Build & deploy Zenlink DEX Aggregator on Kusama. 
* Full function test on Kusama.
* Deploy the whole components to Polkadot including Zenlink DEX Module, DEX Dapp and DEX Aggregator.

## Additional Information
* Medium: https://medium.com/zenlinkpro
* Twitter: https://twitter.com/ZenlinkPro
* Whitepaper: https://github.com/zenlinkpro/whitepaper/blob/master/en/zenlink_whitepaper_en.pdf