Building Blockchain Projects: Building decentralized Blockchain applications with Ethereum and Solidity

259 Pages·2017·4.569 MB·English

by  Narayan Prusty

Building Blockchain Projects

Develop real-time practical DApps using Ethereum and
JavaScript

Narayan Prusty
BIRMINGHAM - MUMBAI
Building Blockchain Projects

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First published: April 2017
Production reference: 1240417
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ISBN 978-1-78712-214-7
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Credits
Author Copy Editor

Narayan Prusty Stuti Srivastava
Reviewers Project Coordinator

Imran Bahsir Nidhi Joshi
Daniel Kraft
Gaurang Torvekar
Commissioning Editor Proofreader

Veena Pagare Safis Editing
Acquisition Editor Indexer

Vinay Argekar Pratik Shirodkar
Content Development Editor Graphics

Mayur Pawanikar Tania Dutta
Technical Editor Production Coordinator

Prasad Ramesh Melwyn Dsa
About the Author
Narayan Prusty is a full-stack developer, with five years of experience in the field. He
specializes in Blockchain and JavaScript. His commitment has led him to build scalable
products for startups, the government, and enterprises across India, Singapore, USA, and
UAE.
At present, Ethereum, Bitcoin, Hyperledger, IPFS, Ripple, and so on are some of the things
he uses on a regular basis to build decentralized applications. Currently, he is a full-time
Blockchain SME (Subject-Matter Expert) at Emirates National Bank of Dubai.
He has already written two books on JavaScript titled Learning ECMAScript 6 and Modern
JavaScript Applications. Both these books were reviewed and published by Packt.
He starts working on something immediately if he feels it’s exciting and solves real work
problems. He built an MP3 search engine at the age of 18, and since then, he has built
various other applications, which are used by people around the globe. His ability to to
build scalable applications from top to bottom is what makes him special.
Currently, he is on a mission to make things easier, faster, and cheaper using the blockchain
technology. Also, he is looking at possibilities to prevent corruptions, fraud, and to bring
transparency to the world using blockchain technology.
You can learn more from him from his blog http://qnimate.com and you can reach him

out at LinkedIn https://www.linkedin.com/in/narayanprusty/.
About the Reviewers
Imran Bashir has an M.Sc. degree in Information Security from Royal Holloway, University
of London, and has a background in software development, solution architecture,
infrastructure management, and IT service management. He is also a member of the
Institute of Electrical and Electronics Engineers (IEEE) and the British Computer Society
(BCS). Imran has sixteen years of experience in public and financial sector. He had worked
on large-scale IT projects for the public sector before moving to the financial services
industry. Since then, he worked in various technical roles for different financial companies
in Europe’s financial capital, London. He is currently working for an investment bank in
London as Vice President in the technology department.
Daniel Kraft has studied mathematics and physics and holds a PhD degree in applied
mathematics from the University of Graz in Austria. He has been involved in development
with cryptocurrencies since 2013, has been the lead developer and chief scientist for both
Namecoin and Huntercoin since 2014, and has published two research papers about
cryptocurrency in peer-reviewed journals. He works as a software engineer and is a
cofounder of Crypto Realities Ltd, a start-up that works on building decentralized
multiplayer game worlds with blockchain technology.
Gaurang Torvekar has a master's degree in Information Systems from Singapore
Management University. He is the cofounder and CTO of Attores, a Smart Contracts as a
Service company, based in Singapore. He has extensive experience in Ethereum and
Hyperledger application development. He has been a speaker at several blockchain
conferences, conducted many hands on blockchain courses in Polytechnics in Singapore,
and is also a Blockchain mentor at Angelhack.
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Table of Contents
Preface
1
Chapter 1: Understanding Decentralized Applications
6
What is a DApp? 7
Advantages of decentralized applications 8
Disadvantages of decentralized applications 8
Decentralized autonomous organization 9
User identity in DApps 9
User accounts in DApps 11
Accessing the centralized apps 11
Internal currency in DApps 12
Disadvantages of internal currency in DApps 13
What are permissioned DApps? 13
Popular DApps 13
Bitcoin 14
What is a ledger? 14
What is blockchain? 14
Is Bitcoin legal? 15
Why would someone use Bitcoin? 15
Ethereum 15
The Hyperledger project 16
IPFS 16
How does it work? 17
Filecoin 17
Namecoin 18
.bit domains 18
Dash 19
Decentralized governance and budgeting 20
Decentralized service 20
BigChainDB 21
OpenBazaar 21
Ripple 22
Summary 23
Chapter 2: Understanding How Ethereum Works
24
Overview of Ethereum 25
Ethereum accounts 25
Transactions 26
Consensus 26
Timestamp 28
Nonce 28
Block time 29
Forking 32
Genesis block 32
Ether denominations 33
Ethereum virtual machine 33
Gas 34
Peer discovery 35
Whisper and Swarm 35
Geth 36
Installing geth 36
OS X 37
Ubuntu 37
Windows 37
JSON-RPC and JavaScript console 37
Sub-commands and options 38
Connecting to the mainnet network 38
Creating a private network 38
Creating accounts 38
Mining 39
Fast synchronization 39
Ethereum Wallet 40
Mist 41
Weaknesses 43
Sybil attack 43
51% attack 43
Serenity 43
Payment and state channels 44
Proof-of-stake and casper 44
Sharding 45
Summary 45
Chapter 3: Writing Smart Contracts
46
Solidity source files 46
The structure of a smart contract 47
Data location 48
What are the different data types? 49
Arrays 50
[ ii ]