Preface

Blockchain is growing massively, and is changing the way that business is done. Leading organizations are already exploring the possibilities of blockchain. With this book, you will learn how to build end-to-end, enterprise-level decentralized applications (DApps) and scale them across your organization to meet your company's needs. This book will help you understand what DApps are and the workings of the blockchain ecosystem with some real-world examples. This is an extensive end-to-end book covering every aspect of blockchain, such as its applications for businesses and developers. It will help you be aware of the process flows so you can incorporate them into your own enterprise. You will learn how to use J.P. Morgan's Quorum to build blockchain-based applications. You will also be introduced to how to write applications that can help communicate in enterprise blockchain solutions. You will learn how to write smart contracts that run without censorship and third-party interference.Once you have a good grip on what blockchain is and have learned all about Quorum, you will jump into building real-world practical blockchain applications for sectors such as payment and money transfer, healthcare, cloud computing, supply chain management, and much more.

Who this book is for

This book is for innovators, digital transformers, and blockchain developers who want to build end-to-end DApps using blockchain technology. If you want to scale your existing blockchain system across the enterprise, you will find this book useful too. It gives you the practical approach needed for solving real problems in an enterprise using a blend of theory- and practice-based approaches.

What this book covers

Chapter 1, What are Decentralized Applications?, will explain what DApps are and provide an overview of blockchain-based DApps.  

Chapter 2, Building Blockchain Using Quorum, introduces the basics of Ethereum blockchain and the features of Quorum. This chapter also teaches you how to set up a Raft network using Quorum and various third-party tools and libraries. 

Chapter 3, Writing Smart Contracts, shows how to write smart contracts and use geth's interactive console to deploy and broadcast transactions using web3.js.

Chapter 4, Getting Started with web3.js, introduces web3.js and how to import and connect to geth, and explains how to use it in Node.js or client-side JavaScript.

Chapter 5, Building Interoperable Blockchains, explores what interoperable blockchains can achieve, the various technologies and patterns for achieving blockchain interoperability, and building interoperable blockchain networks to represent FedCoins. 

Chapter 6, Building Quorum as a Service Platform, will teach you the basics of cloud computing and containerization by examples. You'll learn how to install minikube, deploy containers on Kubernetes, and develop a Quorum-as-a-service using QNM.  

Chapter 7, Building a DApps for Digitizing Medical Records, gets into how to use proxy re-encryption to enable encrypted data sharing in blockchain. Besides proxy re-encryption, you'll also learn about a lot of JavaScript and Python libraries, such as etherumjs-wallet, ethereumjs-tx, ethereumjs-util, and npre. Also, you'll learn about signing transactions using keys stored outside a geth node. 

Chapter 8, Building a Payment Solution for Banks, looks at how to implement network permissioning in Quorum and  how to build a solution to transfer money using a mobile number. 

To get the most out of this book

You must have experience with the JavaScript and Python programming languages.

You must have developed distributed web applications before.

You must understand the basic cryptography concepts, such as signing, encryption, and hashing.

Download the example code files

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We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

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: "This Raft ID will appear while adding a node using raft.addPeer."

A block of code is set as follows:

url = "http://127.0.0.1:9002/"
port = 9002
storage = "dir:./cnode_data/cnode2/"
socket = "./cnode_data/cnode1/constellation_node2.ipc"
othernodes = ["http://127.0.0.1:9001/"]
publickeys = ["./cnode2.pub"]
privatekeys = ["./cnode2.key"]
tls = "off"

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

git clone https://github.com/jpmorganchase/quorum.git
cd quorum
make all

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example:"Now select a file, enter the owner's name, and click on Submit. ."

Note

Warnings or important notes appear like this.

Note

Tips and tricks appear like this.

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