E-Mine Token Generator

This project was created at BIOTS 2018, a hackathon about blockchain and IOT hosted at ETH Zurich. The complete project documentation is available here.

E-Mine Token Generator is a web service through which users can submit requests for creation and deployment of their smart contracts on the Ethereum network. It is built using Flask and can be accessed through a REST API. User makes a request for a smart contract and provides relevant parameters. E-Mine Token Generator then prepares an actual smart contract by filling a template of Solidity code, compiles it and broadcasts it on Ethereum network. Currently it supports compilation and deployment of several standard tokens which are available in OpenZeppelin framework. For compilation and deployment on the server side we used Truffle - a Node.js based development framework for Ethereum smart contracts. In order to test our system we set up a local Ethereum network using Ganache, a tool which is a part of the Truffle framework. Ganache features an internal Javascript implementation of Ethereum blockchain, as well as built-in blockchain explorer that allows easy testing and debugging of distributed applications.

Token Templates

As a basis for token creation we use OpenZeppelin, a framework to build secure smart contracts on Ethereum. For each token type a template is provided, implemented as an extended class of corresponding OpenZeppelin token implementation. Following token templates are provided:

Standard	Token	Description
ERC20	Standard token	Implementation of the basic standard token
	Basic token	Standard token with no allowances
	Pausable token	Standard token modified with pausable transfers
	Mintable token	A Simple ERC20 with mintable token creation
	Capped token	Mintable token with a token cap
	Burnable token	Token that can be irreversibly burned (destroyed)
ERC721	Generic ERC721 token	Generic implementation for the required functionality of the ERC721 standard
ERC827	Generic ERC827 token	ERC827 implementation - ERC20 standard with extra methods to transfer value
		and data and execute calls in transfers and approvals

Each template contains placeholders for custom user parameters provided by the client application. Currently, the following parameters are supported

• Token name - Name of a token.
• Token symbol - Symbol representing the token.
• Decimals - Divisibility of a token, i.e. number of decimal places when displaying token value.
• Initial supply - Initial supply of tokens.

E.g. following code snippet shows placeholders for the Standard token template:

string public constant name = "%token_name%";
string public constant symbol = "%token_symbol%"; 
uint8 public constant decimals = %token_decimals%;
uint256 public constant INITIAL_SUPPLY = %token_initial_supply%;

Provided values can then be used in smart contract functions, such as in the following example of MyStandardToken() constructor that gives initial coin supply to msg.sender:

function MyStandardToken() public {
   totalSupply_ = INITIAL_SUPPLY;
   balances[msg.sender] = INITIAL_SUPPLY;
   Transfer(0x0, msg.sender, INITIAL_SUPPLY);
}

Each template can be easily extended to introduce new smart contract (token) parameters and functions according to the specific user requirements.

REST API

REST API is implemented as a python script with the following supported operations:

API URL	Method	Required/Optional variables	Expected response
/api/requests/	GET	id=[uuid]
/api/tokens/types	GET		{ "types": [
			"MyBasicToken",
			"MyBurnableToken",
			"MyCappedToken",
			"MyERC721Token",
			"MyERC827Token",
			"MyMintableToken",
			"MyPausableToken",
			"MyStandardToken" ]}
/api/tokens/create	POST	tokenName=[string]	{"created": [datetime],
		symbol=[string]	"key": [uuid],
		maxSupply=[integer]	"status":
		decimals=[integer]	"success" or "pending" or "failure",
		genesisSupply=[integer]	"token_abi": [base64 encoded JSON value],
			"token_addr",
			"updated": [datetime],
			"version": 1}

The endpoint /api/tokens/create is called to compile and deploy a new smart contract to the network. With the key field of the response, the endpoint /api/requests/<key> can be called to obtain status results. On deployment success, the response contains the contract address (token_addr) and token ABI (token_abi).

HTTP Return code conventions

Response code for successfull requests are always 200. If a response code is not 200, the json response contains a field error with the error message.

Mobile Client

We extended an existing Android application (see https://github.com/e-mine1/GenesisApp) to test the API. A demo video can be seen below.

Installation

Installing Prerequisites

• Python3+, pip3
• nodejs, npm
• Ganache: http://truffleframework.com/ganache/

# install pip dependencies
$ pip install -r requirements.txt
   
# install truffle
$ npm install -g truffle

Running the Backend

# fire up local dev server
$ ./run.sh

# run Ganache

The E-Mine REST API is exposed at localhost:5000/api/.

Source Files

• emine_web.py: REST backend
• solc_compile_deploy.py: modules to compile and deploy contracts
• db.py: database wrapper