First, create a mintable token

// SPDX-License-Identifier: MIT
// @nhancv
pragma solidity 0.8.4;

interface IMintable {
  function mint(address account, uint256 amount) external;
}

ERC20Mintable

// SPDX-License-Identifier: MIT
// @nhancv
pragma solidity 0.8.4;

import "@openzeppelin/contracts-upgradeable/access/AccessControlUpgradeable.sol";
import "./ERC20Token.sol";
import "./interfaces/IMintable.sol";

contract ERC20Mintable is ERC20Token, IMintable, AccessControlUpgradeable {
  bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");

  /**
   * @dev Upgradable initializer…

To get interface id, use

type(ITest).interfaceId

Remember interfaceId = xor of all selectors (methods) name and param type, don't care to return type

For example:

• Return zero with empty interface

=> bytes4: 0x00000000// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;interface ITest {
}contract Test is ITest {…

If you are a smart contract developer, you will need to consider something about the contract:

• Clean: No unused code, nonsense comment,
• Well document: Comment to all functions
• Formatted: Reformat, reformat, reformat
• Unit test all functions
• Migration for testnet and mainnet
• Avoid duplication code, avoid using too many unnecessary modifiers…

I have some exp with this kind of topic “Dividend Token”. Just share some thoughts

What is “Dividend Token”?

You should search for more detail. =]] But you can go with some token like BabyCake, SafeMoon, ThunderCake, … cake family. :3

The token has some tax or fee on each transaction (transfer, buy, sell)…

Preparing source

• Clone pancake-swap-core

git clone git@github.com:pancakeswap/pancake-swap-core.git
cd pancake-swap-core
git checkout -b factory 3b214306770e86bc3a64e67c2b5bdb566b4e94a7
yarn install
yarn compile

• Clone pancake-swap-periphery

git clone git@github.com:pancakeswap/pancake-swap-periphery.git
cd pancake-swap-periphery
git checkout -b router d769a6d136b74fde82502ec2f9334acc1afc0732
yarn install
yarn add @uniswap/v2-core@"file:../pancake-swap-core"
yarn compile…

Config Server

• Install here: https://www.zabbix.com/download?zabbix=5.4&os_distribution=ubuntu&os_version=20.04_focal&db=postgresql&ws=nginx
• Config server:

nano /etc/zabbix/zabbix_server.conf===>Update DB information

• Config frontend web

nano /etc/zabbix/web/zabbix.conf.php
===># Update DB information, must be matched with server config above
....# Integrate with server
ZBX_SERVER = '**your zabbix ip address or name**';
ZBX_SERVER_PORT = '10051';
ZBX_SERVER_NAME = '**your zabbix hostname**';Example
$ZBX_SERVER…

• A contract has an infinite internal storage
• There are 2 limits to practicality: gas costs and the block gas limit.

Example

Create 5k5 players, read one time

https://testnet.bscscan.com/address/0x721ff9e58831b698efd26b9ac744cf8f0aaecbc2#readContract

Max Gas Limit is 28,500,000 at May 12, 2021 = 0.22BNB ~ $145

• [WRITE] Can add 500 player in 1 tx
• [READ] Can…

Setup MongoDB

* Check linux version: lsb_release -a
sudo apt install wget
wget -qO - https://www.mongodb.org/static/pgp/server-4.4.asc | sudo apt-key add -

* https://docs.mongodb.com/manual/tutorial/install-mongodb-on-debian/
* Debian 10 "Buster"
echo "deb http://repo.mongodb.org/apt/debian buster/mongodb-org/4.4 main" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.4.list

* https://docs.mongodb.com/manual/tutorial/install-mongodb-on-ubuntu/
* Ubuntu 20.04 (Focal)
echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/4.4 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.4.list

sudo apt update
sudo apt install -y build-essential
sudo…