To make usage of the content of this book, basic prior knowledge of computing and general programming concepts is needed. If you feel you don't have that knowledge, it is always possible to catch up the basic requirements with a fast reading on many beginners' books on programming. This book is essentially intended for blockchain architects, developers, consultants, and IT engineers who are using blockchain to provide advanced services to end customers and employers. If you are also willing to write smart contracts solution on Ethereum, then this book is ideal for you. If you already have some experience with JavaScript, this book can help you speed up with it in a fast-paced way.

Chapter 1, Introduction to Blockchain, Ethereum, and Smart Contracts, takes you through the fundamentals of blockchain, its terminology and jargon, advantages, problems it’s trying to solve, and industry relevance. It will explain the important concepts and architecture in detail. This chapter will also teach you about concepts specific to Ethereum. In this chapter, details about its concepts like externally owned accounts, contract accounts, its currency in terms of gas and Ether will be discussed. Ethereum is heavily based on cryptography and you’ll also learn about hash, encryption, and usage of keys for creating transactions and accounts. How are transactions and accounts created, how gas is paid for each transaction, difference between message calls and transactions, and storage of code and state management will be explained in detailed.

Chapter 2, Installing Ethereum and Solidity, takes you through creating a private blockchain using Ethereum platform. It will provide step-by-step guidance for creating a private chain. Another important tool in Ethereum ecosystem is ganache-cli. This chapter will also show the process of installing ganache-cli and using it for deploying Solidity contracts, installing Solidity, and using it to compile Solidity contracts. You will also install Mist, which is a wallet and can interact with private chain. Mist will be used to create new accounts, deploy contracts, and use contracts. Mining of transactions will also be shown in this chapter. Remix is a great tool for authoring Solidity contracts.

Chapter 3, Introducing Solidity, begins the Solidity journey. In this chapter, you’ll learn the basics of Solidity by understanding its different versions and how to use a version using pragmas. Another import aspect of this chapter is to understand the big picture of authoring smart contracts. Smart contract layout will be discussed in depth using important constructs like state variables, functions, constant function, events, modifiers, fallbacks, enums, and structs. This chapter discusses and implements the most important element of any programming language—data types and variables. There are data types that are simple and complex, value types and reference types, and storage and memory types—all these types of variables will also be shown using examples.  

Chapter 4, Global Variables and Functions, provides implementation and usage details of block- and transaction-related global functions and variables and address- and contract-related global functions and variables. These comes in very handy in writing any series of smart contract development.

Chapter 5, Expressions and Control Structures, teaches you how to write contracts and functions that will have conditional logic using if...else and switch statements. Looping is an important part of any language and Solidity provides while and for loops for looping over arrays. Examples and implementation of looping will be part of this chapter. Loops must break based on certain conditions and should continue based on other conditions.

Chapter 6, Writing Smart Contracts, is the core chapter for the book. Here, you will start writing serious smart contracts. It will discuss the design aspects of writing smart contracts, defining and implementing a contract, and deploying and creating contracts using different mechanisms using the new keyword and using known addresses. Solidity provides rich object orientation, and this chapter will delve deep into object-oriented concepts and implementation such as inheritance, multiple inheritance, declaring abstract classes and interfaces, and providing method implementations to abstract functions and interfaces. 

Chapter 7, Functions, Modifiers, and Fallbacks, shows how to implement basic functions that accept inputs and return outputs, functions that just output the existing state without changing the state and modifiers. Modifiers help in organizing code better in Solidity. It helps in security and reusing code within contracts. Fallbacks are important constructs and are executed when a function call does not match any of the existing function signatures. Fallbacks are also important for transferring Ether to contracts. Both modifiers and fallbacks will be discussed and implemented with examples for easy understanding.

Chapter 8, Exceptions, Events, and Logging, is important in Solidity from contract development perspective. Ether should be returned to caller in case of error and exception. Exception handling will be explained and implemented in depth in this chapter using newer Solidity constructs like assert, require, and revert. The hrow statement will also be discussed. Events and logging help in understanding the execution of contracts and functions. This chapter will show and explain the implementation for both events and logs.

Chapter 9, Truffle Basics and Unit Testing, covers the basics of truffle, understanding its concepts, creating a project and understanding its project structure, modifying its configuration, and taking a sample contract through entire life cycle of writing, testing, deploying, and migrating a contract. Testing is as important for contracts as writing a contract. Truffle helps in providing a framework to test; however, tests should be written. This chapter will discuss the basics of unit test, write unit test using Solidity, and execute those unit tests against the smart contract. Unit tests will be executed by creating transaction and validating its results. This chapter will show implementation details to write and execute unit tests for a sample contract.

Chapter 10,Debugging Contracts, will be show troubleshooting and debugging using multiple tools like Remix and events. This chapter will show how to execute code line by line, check state after every line of code, and change contract code accordingly.

This book assumes a basic level knowledge of programming. It is ideal to have some background on any scripting language. All you need is an internet connectivity and a browser for using a majority of this book. There are sections that will need creating a machine to deploy blockchain specific tools and utilities. This machine can be physical or virtual, on cloud or on-premise.

{  
"config": {
"chainId": 15,
"homesteadBlock": 0,
"eip155Block": 0,
"eip158Block": 0
},
"nonce": "0x0000000000000042",
"mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"difficulty": "0x200",
"alloc": {},
"coinbase": "0x0000000000000000000000000000000000000000",
"timestamp": "0x00",
"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"gasLimit": "0xffffffff",
"alloc": {
}
}

[default]
exten => s,1,Dial(Zap/1|30)
exten => s,2,Voicemail(u100)
exten => s,102,Voicemail(b100)
exten => i,1,Voicemail(s0)

npm install -g ganache-cli

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