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- Herausgeber: Packt Publishing
- Kategorie: Lebensstil
- Sprache: Englisch
Blockchain is a technology that powers the development of decentralized applications.This technology allows the construction of a network with no single control that enables participants to make contributions to and receive benefits from the network directly.
This book will give you a thorough overview of blockchain and explain how a blockchain works.You will begin by going through various blockchain consensus mechanisms and cryptographic hash functions. You will then learn the fundamentals of programming in Solidity – the defacto language for developing decentralize, applications in Ethereum. After that, you will set up an Ethereum development environment and develop, package, build, and test campaign-decentralized applications.The book also shows you how to set up Hyperledger composer tools, analyze business scenarios, design business models, and write a chain code. Finally, you will get a glimpse of how blockchain is actually used in different real-world domains.
By the end of this guide, you will be comfortable working with basic blockchain frameworks, and develop secure, decentralized applications in a hassle-free manner.
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Seitenzahl: 226
Veröffentlichungsjahr: 2018
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Blockchain Quick Start Guide
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First published: December 2018
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Contributors
About the authors
Xun (Brian) Wu is an author, founder, and advisor. He has over 17 years of extensive hands-on experience in the design and development of blockchain, big data, cloud, UI, and system infrastructure. He has worked for top investment banks including JP. Morgan, Citigroup, and the Bank of America. He is the co-author of Seven NoSQL Databases in a Week, Hyperledger Cookbook, and Blockchain By Example,published by Packt. He has been a technical reviewer for more than 50 computer technical books for Packt Publishing. He serves as a board advisor for several blockchain start-ups. He owns several patents on blockchain. Brian holds a master's degree in computer science from NJIT. He lives in New Jersey with his two beautiful daughters, Bridget and Charlotte.
Weimin Sun has 20 years of experience of working in the financial industry. He has worked for top-tier investment and commercial banks such as J.P. Morgan, Bank of America, Citibank, and Morgan Stanley. He has managed large teams developing IT applications. He has held corporate titles such as Executive Director and Senior VP. He has in-depth knowledge of blockchain technology, data architecture, data modeling, data science, and big data platforms. He is an expert in designing data-driven solutions. He has a Ph.D, an M.B.A, and an M.Sc. He has published several papers on statistics in renowned academic journals. Weimin lives in New Jersey, USA, with his beautiful wife and his talented son.
About the reviewers
Aasim Ali is a full-stack blockchain engineer at Inncretech LLC, Princeton, New Jersey. He has a master's degree in information systems with a graduate certification in business intelligence from Stevens Institute of Technology, Hoboken, New Jersey. He works with the blockchain and data science R&D team making POCs around AI, Ethereum, and Hyperledger for clients to incorporate in their proprietary systems, which helps them upgrade to new cutting-edge technologies.
F. Richard Yu is the chair of the IEEE P2418.3/4 blockchain standards, IEEE fellow, IET fellow, and professor at Carleton University, Canada. He is the leading general co-chair of IEEE conference on blockchain, 2019. Professor Yu has published 6 books and over 490 papers in international top-tier academic journals and conferences, with over 13,000 citations and an H-index of 63. He holds 27 international patents, and his innovative works have been incorporated into industry standards, impacting on millions of pieces of network equipment and billions of mobile devices. He received his PhD from the University of British Columbia (UBC) in 2003.
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Table of Contents
Title Page
Copyright and Credits
Blockchain Quick Start Guide
About Packt
Why subscribe?
Packt.com
Contributors
About the authors
About the reviewers
Packt is searching for authors like you
Preface
Who this book is for
What this book covers
To get the most out of this book
Download the example code files
Conventions used
Get in touch
Reviews
Introduction to Blockchain Technology
The genealogy analogy
Bitcoin
Why Bitcoin
A peer-to-peer network
Cryptography and hash functions
The distributed ledger, blocks, transactions, addresses, and UTXO
The consensus mechanism
Forking
Mining and difficulty level
Hacking – the 51% problem
Private keys and Bitcoin wallets
Bitcoin scripting
Altcoins
Ethereum
Enterprise blockchain – Hyperledger
The evolution of blockchain
Summary
Ethereum Fundamentals
An overview of Ethereum
Ethereum basic concepts
Ether
ERC20 tokens
Smart contracts
Ethereum virtual machines
Ethereum gas
Account
Oracle
Other concepts
Performance
Throughput
Proof-of-Stake (PoS)
Casper
Plasma
Sharding
Summary
Overview of Solidity Programming
What is solidity?
Tools for solidity development environment
Browser-based IDE
Remix
EthFiddle
Command-line development management tools
Truffle
Introduction to smart contracts
Layout of a solidity source file
Pragma
Comments
Import
Paths
Relative paths
Structure of a contract
State variables
Data type
Enum type
Struct type
Mapping
Functions
Input parameters
Access modifiers
Output parameters
Modifiers
Events
Constructor
Constant state variables, unit, and functions
Ether units
Time units
Inheritance, abstract, and interface
Common smart contract patterns
Access restriction
State machine
Smart contract security
Keep contract simple and modular
Use the checks-effects-interactions pattern
DoS with block gas limit
Handle errors in external calls
Case study – crowdfunding campaign
Summary
Building an Ethereum Blockchain Application
Decentralized application overview
web3.js quick overview
Provider
DApp development tools
Truffle
Ganache
Setting up an Ethereum development environment
Installing Truffle
Installing Ganache
Creating a Truffle project
Launching the Ganache environment
Deploying a smart contract
Writing a campaign decentralized application
Selecting a web3 provider
Loading account information
Loading project information
Handling the fund function
checkGoalReached
Summary
Exploring an Enterprise Blockchain Application Using Hyperledger Fabric
Key concepts in Hyperledger Fabric
Ledger
Chaincode
Channel
Core component model
Peers
Membership service provider (MSP)
Certificate authority (CA)
Ordering service
Hyperledger Fabric basic transaction flow
Issuance claim
Setting up a Hyperledger Fabric environment
Installation prerequisites
Installing Hyperledger Fabric
Writing chaincode
Development tools
LiteIDE 
JetBrains Gogland
Visual Studio Code
Chaincode key concept and APIs
Defining an issuance claim
Initializing the chaincode
Invoking the chaincode
AddCompany
ReportLost
RequestedInfo
SubmitClaim, ConfirmClaimSubmission, ApproveClaim
Query
getHistory
Configuring Hyperledger Fabric
Generating the certificate
Generating an orderer genesis block
Generating a channel configuration transaction
Overview of Hyperledger Fabric Docker composer configuration files
Fabric project directory structure
Docker-compose-base.yaml
Peer-base.yaml
Starting the Hyperledger Fabric network
Creating a channel
Joining channels
Updating the anchor
Installing chaincode
Instantiating the chaincode
Invoking add broker
Invoking add insurer
Invoking ReportLost
Invoking RequestedInfo
Invoking SubmitClaim
Invoking ConfirmClaimSubmission
Invoking ApproveClaim
Querying claim history
End-to-end test execution 
Summary
Implementing Business Networks Using Hyperledger Composer
Hyperledger Composer – a quick overview
Yeoman generator
Composer REST server
LoopBack connector
JavaScript SDK
Composer playground
Composer-cli
Setting up a Hyperledger Composer environment
Installation prerequisites
Installing the development environment
Analyzing business scenarios
Business network archive
Network model file (.cto)
Script file (.js)
Access control list (ACL) file (.acl)
Query file (.qry)
Designing business models
Implementing the business transaction function
Testing in the playground
Deploying a business network
Integrating with REST server
Generating the Hyperledger Composer REST API
Summary
Blockchain Use Cases
Blockchain use case examples
Payment and settlement services
Import and export finance
Immutable ledger
Regulatory compliance and auditing
Identity theft detection
Funds back-office operation
Collateral management
Healthcare systems
Real estate trading and rental markets
IP market
Elections
HR and recruiting
Public records
Reduce contract disputes
Sharing economy
Integration with IoT
Facilitate commercial and social relationships
How to choose a proper use case
DApp use case – healthcare data sharing
The business problem
A blockchain solution
Summary
Other Books You May Enjoy
Leave a review - let other readers know what you think
Preface
Just as we were at the dawn of the internet age in the nineties, we are at the dawn of the blockchain age now. This new technology will disrupt existing business models and give birth to new ones. It will inspire the emergence of community economies built on blockchain networks, where every participant makes contributions to and receives benefits from the community. There will no longer be a single entity controlling and receiving dividends from the economy.
Thanks to its immutability, transparency, and the consensus mechanism for avoiding double-spending, along with other clever designs such as blocks chained with the hashes of the previous blocks, the technology allows untrusting parties to trade with each other directly. As a result, most of the intermediary services currently provided by existing institutions will no longer be needed. As a consequence, blockchain technology is receiving attention the world over.
There are many articles and books on blockchain. However, there are no good books serving beginners who are looking for a quick way to gain a good understanding of the technology as a whole and learn what's needed to be able to develop a complete blockchain application. This quick guide fills in this gap. The book covers coding details on how to develop blockchain applications on Ethereum and Hyperledger Fabric, the two most popular platforms for public and enterprise blockchain, respectively.
Who this book is for
This book benefits readers who are new to the blockchain technology and want to learn about its basics and jump start their development of smart contracts and Decentralized Applications (DApps). Business readers can especially gain from the first two chapters along with the last chapter, which cover what business issues need to be addressed and what possible use cases there are for blockchain. IT readers should read all the chapters and learn how to develop smart contracts and DApps via the many working examples presented in this book.
What this book covers
Chapter 1, Introduction to Blockchain Technology, gives an overview of blockchain and its key concepts, such as cryptography and hash algorithms, the distributed ledger, transactions, blocks, proof of work, mining, and consensus. We cover Bitcoin, the mother of blockchain technology, in detail. We briefly introduce Ethereum by pointing out some limitations of Bitcoin and how they are addressed by Ethereum. While Bitcoin and Ethereum are examples of public blockchains, IBM's Hyperledger is used as an example of enterprise blockchains. Toward the end of this chapter, we look at the evolution of blockchain, through 1.0, 2.0, 3.0, and beyond, and we examine their use cases.
Chapter 2, Ethereum Fundamentals, covers the basic concepts of Ethereum, such as smart contracts, ether, consensus algorithms, EVM, gas, and accounts. We will discuss Ethereum performance and review ideas on how to improve the overall performance via proof of work, casper, plasma, and sharding.
Chapter 3, Overview of Solidity Programming, discusses what solidity is, as well as the tools for the solidity development environment. We then discuss smart contracts and their common patterns. We cover the important topic of smart contract security. Finally, we show how to write a smart contract with a use case of crowdfunding.
Chapter 4, Building an Ethereum Blockchain Application, looks at what a DApp is. We give a quick overview of web3.js. We explain how to set up an Ethereum development environment, as well as how to develop and test a DApp.
Chapter 5, Exploring an Enterprise Blockchain Application Using Hyperledger Fabric, gets into the key concepts of Hyperledger Fabric, along with the core components. We explain how to create a Hyperledger Fabric environment, how to write a chaincode, and how to set up Hyperledger Fabric configuration.
Chapter 6, Implementing a Business Network Using Hyperledger Composer, provides an overview of Hyperledger Composer and talks about how to set up a Hyperledger Composer environment. We discuss business scenarios, the business network archive, and how to implement a business transaction function.
Chapter 7, Blockchain Use Cases, first talks about popular blockchain use cases across industries, including the financial sector, civil services, supply chains, the Internet of Things (IoT), and healthcare, at a high level. We will then proceed to a discussion of the proper use cases for DApps, before then developing a successful DApp. Finally, we take the health data-sharing use case and comment at a high level on building an DApp for it.
To get the most out of this book
We've focused on organizing the book to fit business and IT beginners in blockchain technology. The chapters are arranged to ensure that they can be followed easily and flow naturally.
Business users can skip the chapters with detailed descriptions on how to develop blockchain applications and, instead, focus on the chapters with general descriptions of the technology and use cases.
Veteran IT professionals on blockchain can skip the general description chapters and focus on chapters either on Ethereum or Hyperledger, from which they will gain insights on how to build blockchain applications.
It is recommended that IT users download the code and make modifications for adopting to their own use cases or exercises.
Download the example code files
You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packt.com/support and register to have the files emailed directly to you.
You can download the code files by following these steps:
Log in or register at
www.packt.com
.
Select the
SUPPORT
tab.
Click on
Code Downloads & Errata
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Enter the name of the book in the
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box and follow the onscreen instructions.
Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:
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Zipeg/iZip/UnRarX for Mac
7-Zip/PeaZip for Linux
The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Blockchain-Quick-Start-Guide. In case there's an update to the code, it will be updated on the existing GitHub repository.
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: "One important interface is ChaincodeStubInterface, which provides functions that allow you to query, update, and delete assets in the ledger."
A block of code is set as follows:
contract SimpleStorage { uint storedData; // State 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:
pragma solidity ^0.4.15;import 'zeppelin/contracts/math/SafeMath.sol';….contract ExampleCoin is ERC20 { //SafeMath symbol is from imported file SafeMath.sol' using
SafeMath
for uint256; …}
Any command-line input or output is written as follows:
mkdir ~/insurance-claim && cd ~/insurance-claim
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: "When the preceding request is validated by mining nodes, the HelloWorld smart contract is invoked."
Get in touch
Feedback from our readers is always welcome.
General feedback: If you have questions about any aspect of this book, mention the book title in the subject of your message and email us at [email protected].
Errata: Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you have found a mistake in this book, we would be grateful if you would report this to us. Please visit www.packt.com/submit-errata, selecting your book, clicking on the Errata Submission Form link, and entering the details.
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If you are interested in becoming an author: If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, please visit authors.packtpub.com.
Reviews
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Introduction to Blockchain Technology
Blockchain technology will disrupt current business models by making intermediary services obsolete. The term blockchain has become a buzzword worldwide. IT technologists are picking up blockchain books in flocks and starting to read about it in the hope of mastering the basic concepts. People are motivated to become professional blockchain application developers. Unless you pick up a well-written book, it often requires you to read many books and articles before the concepts of the blockchain become clear. To assist you in gaining a concise view of how an end-to-end blockchain application works, we outline a high-level introduction of the basic concepts along with the code-level details explaining how an actual application can be developed step by step. At the end of this book, we cover blockchain use cases in examples to inspire you to work on life-changing projects.
In this chapter, we give an overview of blockchain, along with its key concepts such as cryptography and hash algorithms, the distributed ledger, transactions, blocks, proof of work, mining, and consensus. We cover Bitcoin, the mother of blockchain technology, in detail. We briefly introduce Ethereum by pointing out some limitations of Bitcoin and how they are addressed by Ethereum. While Bitcoin and Ethereum are examples of public blockchains, IBM's Hyperledger is used as an example of enterprise blockchains. At the end of this chapter, we mention the evolution of the blockchain: blockchain 1.0, 2.0, 3.0, and beyond, based on their use cases. Specifically, we will cover the following topics on blockchain:
A genealogical analogy for blockchain
The Bitcoin consensus mechanism
A brief discussion of Hyperledger
Blockchain evolution
The genealogy analogy
One of the authors recently attended a Chinese university alma mater reunion event in Beijing, where blockchain became a hot discussion topic. A very well-regarded schoolmate and scholar, Professor Yang, who has authored books on cryptography and public data safeguards, used genealogy to describe a blockchain. This is a well-thought-out analogy since it explains blockchain intuitively and easily. The analogy is borrowed here to illustrate the basic ideas behind the technology.
Back in the old days in China, it was a custom for each family of a clan (sharing the same last name) to keep a copy of the genealogical tree of the clan. When members of a family changed due to either marriage or the birth of an offspring, as well as adoption, the new member's name would appear in each copy. However, the new member had to be accepted by the clan before the name could be added in. There were cases when a marriage was not endorsed by a majority of the clan due to various reasons. In this case, the new member's name would not be entered into the genealogy. In other words, when a new member joined in a family, the news was broadcast to other families of the clan. If the clan reached a consensus on accepting the new member, each family would update their copy of the genealogical tree to reflect the change. On the other hand, if the clan decided not to accept the new member, the name would not be added in. The genealogy could be used for verification purposes. For example, if a stranger made a claim to be a member of the clan, or two people with the same last name were eager to find out whether they shared the same ancestor, with the genealogy, it was easy to verify this. The outcome would be accepted since the genealogy was considered reliable thanks to the aforementioned consensus and decentralized records, which were difficult to manipulate unless the majority of families agreed.
A blockchain shares many of the characteristics of a genealogy. They are summarized as follows:
Like a clan consisting of many related families, a blockchain network consists of nodes. Each node is like a family.
Like
every family keeping a copy of the clan's genealogy, each node of a blockchain maintains a copy of all transactions that have occurred on the chain, starting from the very beginning. The collection of all transactions is a
ledger
. This makes a blockchain a decentralized data repository.
A genealogy starts with a common ancestor of the clan and names with direct relationships, such as parents and children, that are connected by a line for linkage. Similarly, a ledger consists of blocks. Each block contains one or multiple transactions depending on the type of blockchain. (As you will see later, blocks on Bitcoin or Ethereum host multiple transactions, while R3's Corda uses a block with only one transaction). Transactions are like names, and a block is similar to the invisible box containing a couple's names. An equivalent of the root ancestor is called the
genesis block
, which is the first block of a blockchain. Similar to a line linking parents and children, a hash, which will later be explained in more detail, points from the current block to its ancestor block.
Like the consensus mechanism for adding new names to a genealogy, the Bitcoin blockchain uses a mechanism called Proof-of-Work to decide whether a block can be added to the chain. Like a genealogy, after a block is added to a chain, it is difficult to change (hack) unless one possesses the majority (which is called a 51% attack) of the computing power of the network.
Genealogy provides transparency in a clan's history. Similarly, a blockchain allows a user to query the whole ledger or just a part of the ledger and find out about coin movements.
Since every family kept a copy of the genealogy, it was unlikely to lose the genealogy even if many copies were lost due to a natural disaster, a war, or other reasons. As long as at least one family survived, the genealogy survived. Similarly, a decentralized ledger will survive as long as at least one node survives.
While genealogy is a good analogy to explain some key concepts of a blockchain, they are not the same. Inevitably, there are features that are not shared by them. For example, the blockchain uses cryptography and hashes extensively for data protection and deterring hackers. A genealogy does not have such a need. Therefore, next we move away from the genealogy analogy and explain key blockchain concepts chronically.
