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Ethereum

The following sections outline essential concepts for constructing smart contracts to develop decentralized applications (DApps) on the Ethereum platform. The intention is to provide key insights rather than a comprehensive guide to building a fully decentralized app.

Solidity​

Solidity is a high-level programming language specifically designed for writing smart contracts on the Ethereum blockchain. Smart contracts are self-executing contracts with the terms of the agreement directly written into code. Solidity allows developers to create these smart contracts, defining the rules, logic, and functionality of decentralized applications (DApps) on the Ethereum network. It is a fundamental tool for Ethereum developers to build and deploy blockchain-based applications with programmable features.

SPDX-License-Identifier​

SPDX-License-Identifier in Solidity is a comment pragma that specifies the license under which the Solidity source code is distributed. SPDX stands for Software Package Data Exchange, and it provides a standard format for communicating the components, licenses, and copyrights associated with a software package.

By including SPDX-License-Identifier in the Solidity source code as a comment, developers can explicitly state the license under which their smart contracts are released. This helps in promoting transparency, ensuring compliance with licensing terms, and making it clear for other developers or users how they can use, modify, and distribute the code.

For example:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract MyContract {
    // Contract code goes here
}

In this example, the MIT license is specified, indicating that the code is released under the terms of the MIT License. Developers can replace MIT with the appropriate SPDX license identifier that corresponds to the chosen license for their Solidity code.

You need to use license according to your project. Some other licenses are:

// SPDX-License-Identifier: GPL-3.0-or-later

You can find list of licenses here: https://spdx.org/licenses/

What is Software Package Data Exchange(SPDX)?

The right which granted by an application owner depends on which license the developer selects. Most projects use one of a few standard licenses, but they're not always clearly communicated. For example, a project may be released under "the GNU General Public License (GPL)." But which version? And can the recipient choose a later version if they wish?

SPDX is intended to solve the confusion of above questions. Futher reading: SPDX clears confusion around software licenses

Libraries​

Here are some Javascript libraries that I found it handy when developing smart contracts.

  • Ethers is a very it's a great library for interacting with the Ethereum blockchain.
  • Hardhat is going to be our development environment. It's what's going to allow our project to compile contracts and to deploy contracts. hardhat can also initialize our solidity contracts for us and get the project rolling so it can do a little bit of that boilerplate,
  • Web3 model in order to be connecting with our provider.
  • OpenZeppelin is a library which actually contains the ERC-721 contracts already built to standard. So in this project, we're not going to be building out all of our NFT tokens from scratch. We're going to be leveraging this library, which is an excellent library and resource to use when building a Marketplace. link
  • ipfs-http-client - IPFS is a decentralized way of hosting our NFT images and our files, the actual files we're going to be storing with IPFS. With IPFS client, we can actually run promises and use JavaScript to hook up to our IPFS so that when our users are actually tokenizing these NFT is they're going to be hosting it with IPFS

Ethereum Services​

  • infura.io
    • Infura's API solutions offer reliable access to IPFS and Ethereum, eliminating the need for lengthy synchronization and complex setups. This platform streamlines every stage of blockchain application development, from testing to scaled deployment, reducing costs and enhancing accessibility for developers.

ERC 721​

ERC 721 is standard protocol of what we need in order to be compliant at an industry level of our NFT. For the full explaination of why they have this compliant contract and why every contract must be compliant. Every compliant contract must implement the following functionality. You may check openzeppelin-contracts ERC721

Polygon​

Polygon is a framework for constructing Ethereum-compatible blockchain networks. It aims to address some of the scalability and usability issues of the Ethereum blockchain by providing a multi-chain scaling solution. Polygon was formerly known as Matic Network.

Testnet​

What is a testnet?

A testnet is a separate blockchain network designed for testing and experimentation purposes. It mimics the functionalities of the main Ethereum network but operates with fake or test Ether (ETH) and has its own tokens, which hold no real-world value. Testnets are crucial for developers and users to test smart contracts, decentralized applications (DApps), and other blockchain-related features in a risk-free environment

The Polygon testnet is called Mumbai, which is a layer-two (L2) scaling platform for Ethereum. Like other testnets, Mumbai allows developers to deploy and test their applications on the Polygon network without having to spend real money. 

In the case of Polygon, their native token is called MATIC, which is trading at around $1 as of May 2022. On the other hand, the test tokens for Mumbai, or testnet MATIC, are distinct from the actual MATIC tokens and do not carry any monetary value. Therefore, developers often use what are called faucets to receive free testnet MATIC for development on Mumbai.

The Mumbai testnet is the testnet of the Polygon network, which replicates the Polygon mainnet. It enables developers to deploy, test, and execute their dApps in the blockchain environment risk-free and at no cost.

How to get started using the Mumbai testnet?​

To use Mumbai to test your dApps, you will first need to set up a node in the network. A popular method is to connect your wallet to the virtual crypto wallet Metamask, which connects to a node by using a node provider like Alchemy. Go visit Alchemy Quickstart Guide for the full setup tutorial.

After you have created a new app with the Mumbai testnet in Alchemy, there is some information you may need to fill out in the Metamask settings to connect to the network:

Remember to replace "your-api-key" in New RPC URL with the API key of your Alchemy app. The Chain ID is one of the default Ethereum chains supported by Metamask. The block explorer URL points to Mumbai Polygonscan, the Mumbai block explorer.  For more details, you can also check out the Mumbai testnet RPC URL documentation.

Local node devleopment​

ERC721 OpenZeppelin Contracts IPFS data hosting with Infura Blockchain Suite Project Management Compile and Deploy Smart Contracts to Blockchain with Hardhat functionality

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