Preface

Blockchain technology is at its nascent stage. However, technology is slowly moving forward and new developments using blockchain are emerging. This technology has the power to replace trusted third parties with trusted blockchain networks. Bitcoin was the birth of blockchain technology and has shown the world a new peer-to-peer payment system without needing intermediaries. You could say that Bitcoin was the first generation of blockchain technology. However, Ethereum took this innovative technology to the next level—you could call it blockchain generation two—where you can write decentralized applications using smart contracts. Solidity is the most widely used and popular language for writing smart contracts for decentralized applications.

The book starts with explaining blockchain, Ethereum, and Solidity. It mostly focuses on writing production-ready smart contracts in the Solidity language for Ethereum blockchain. It covers basic Solidity language syntax and control structures, and moves on to writing your own contract. It also deep dives into different libraries that you can use while writing contracts. Later on, it covers tools and techniques to write secure, production-ready smart contracts.

Who this book is for

This book is for professional software developers who have started learning blockchain, Ethereum, and the Solidity language and who want to make a career in writing production-ready smart contracts. This book is also aimed at developers who are interested in building decentralized applications over Ethereum blockchain. This book will help you learn the Solidity language for building smart contracts from scratch and make you proficient in building production-ready smart contracts for decentralized applications. 

What this book covers

Chapter 1, Introduction to Blockchain, starts with how blockchain technology came into existence through the innovation of Bitcoin. This chapter discusses the different properties of a blockchain. It also introduces Ethereum and how it is different from the Bitcoin blockchain. Later, this chapter introduces smart contracts.

Chapter 2, Getting Started with Solidity, starts with the basic Solidity language syntaxes and the structure of a contract. You will learn about the different data types available in Solidity. This chapter also discusses globally available variables present in the Solidity language that you can use while writing your smart contract.

Chapter 3, Control Structures and Contracts, deep dives into the control structures of Solidity contracts, the different types of functions supported, contract inheritance, and event logging. 

Chapter 4, Learning MetaMask and Remix, discusses setting up your MetaMask plugin and creating wallets using it. This chapter also discusses using the online Remix IDE to create, compile, deploy, and interact with your Solidity contracts.

Chapter 5, Using Ganache and the Truffle Framework, discusses installing and setting up your local blockchain instance using Ganache. This chapter also discusses installing and setting up the Truffle framework, learning how to use its commands, setting up your new Truffle project, writing migration scripts for the Truffle framework, and adding test cases to a project.

Chapter 6, Taking Advantage of Code Quality Tools, discusses improving the quality of your contracts by using open source tools such as surya, which helps in generating different kinds of reports. This chapter also discusses using Solidity linters to lint your code and fix common issues present in your contracts, as well as running Solidity coverage tools to generate code coverage reports.

Chapter 7, ERC20 Token Standard, covers the introduction of the ERC20 token standard. This chapter deep dives into its full implementation details, provides an in-depth study of each function of the standard, and covers different events, optional functions, and a number of advanced functions.

Chapter 8, ERC721 Non-Fungible Token Standard, starts with an introduction to the ERC721 standard and the difference between the ERC20 and ERC721 standards. This chapter deep dives into each of the state variables, functions, and events associated with ERC721 implementation. This chapter also discusses some other optional contracts that can be used with the ERC721 standard.

Chapter 9, Deep Dive into the OpenZeppelin Library, starts with an introduction to OpenZeppelin library contracts. This chapter will help you learn how to install and use OpenZeppelin library contracts in your Truffle project. It also provides in-depth studies of library contracts such as Ownable, Claimable, Roles, PauserRole, Pausable, ERC20, SafeERC20, DetailedERC20, ERC20Mintable, ERC20Burnable, ERC20Pausable, Math, SafeMath, Crowdsale, Address, and ReentrancyGuard.

Chapter 10, Using Multisig Wallets, The multisig wallets are special contracts that require multiple signatures to execute a transaction. This chapter provides an introduction to multisig contracts and their usage. This chapter also covers installing, creating, and setting up your own multisig wallet, as well as how to use and control it.

Chapter 11, Upgradable Contracts Using ZeppelinOS, provides an introduction to the ZeppelinOS development platform. Topics covered include creating a new project using zos commands, creating an upgradable contract, deploying, re-deploying to upgrade the contract, and some precautions to take when using ZeppelinOS for writing upgradable contracts.

Chapter 12, Building Your Own Token, helps you learn how to create your own ERC20 token contract from scratch. You will learn how to draft the specification of a contract, set up a Truffle project, create a contract, choose which OpenZeppelin libraries to use, write migration scripts, write test cases, execute migration scripts and test cases in Ganache, and finally, test your contracts on a testnet such as Rinkeby.

Chapter 13, Solidity Design Patterns, introduces different Solidity design patterns. These are divided into five categories: Security patterns: Withdrawal, Access restriction, and Emergency stop; Creational patterns: Factory pattern; Behavioral patterns: State machine, Iterable map, Indexed map, Address list, and Subscription; Gas economic patters: String comparison and Tight variable packing; and Life cycle patterns: Mortal and Auto deprecate pattern.

Chapter 14, Tips, Tricks, and Security Best Practices, helps you to learn different Solidity smart contract best practices, such as avoiding floating pragma, the 15-second blocktime rule, rounding errors, and gas consumption. It also helps you to learn about different security attacks, such as front-running, reentrancy, signature replay, integer overflow and underflow, and how to prevent these attack patterns.

To get the most out of this book

You should have knowledge of any of the existing programming languages. Solidity language syntaxes are very similar to Java, JavaScript, and Python syntaxes. A developer who has created projects using Java, JavaScript, or Python can pick up and learn Solidity very easily. You should also have some basic knowledge of OOPS concepts, blockchain, wallets, private key, public key, consensus algorithms, and exchanges.

One very important thing to note here is that, in order to write smart contracts for decentralized applications, you need to have a completely new mindset. Up until now, you have probably been building applications using Java, JS, or another language in which you can fix bugs later on, even in the production environment when something goes wrong. However, smart contracts are immutable. If your contract is deployed in production, you are done. If there is a bug left in the contract, you will be unable to fix it. Hence, you need to ensure that all your smart contracts are well-tested and have no bugs present in them. 

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Code in action

To see the code being executed please visit the following link: http://bit.ly/2Yv6kpm.

Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Solidity supports different data types, including uint, int, address, and many more."

A block of code is set as follows:

contract VariableStorage {
   uint storeUint; //uint256 storage variable
    //...
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

contract VariableStorage {
    uint storeUint; //uint256 storage variable
    //...
}

Any command-line input or output is written as follows:

$ npm install -g ganache-cli

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "As mentioned earlier, you can start a local Ganache blockchain instance by just clicking on the QUICKSTART button."

Warnings or important notes appear like this.

Tips and tricks appear like this.

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