Book Image

Building Blockchain Projects

By : Narayan Prusty
Book Image

Building Blockchain Projects

By: Narayan Prusty

Overview of this book

Blockchain is a decentralized ledger that maintains a continuously growing list of data records that are secured from tampering and revision. Every user is allowed to connect to the network, send new transactions to it, verify transactions, and create new blocks, making it permission-less. This book will teach you what blockchain is, how it maintains data integrity, and how to create real-world blockchain projects using Ethereum. With interesting real-world projects, you will learn how to write smart contracts which run exactly as programmed without any chance of fraud, censorship, or third-party interference, and build end-to-e applications for blockchain. You will learn about concepts such as cryptography in cryptocurrencies, ether security, mining, smart contracts, solidity, and more. You will also learn about web sockets, various API services for Ethereum, and much more. The blockchain is the main technical innovation of bitcoin, where it serves as the public ledger for bitcoin transactions.
Table of Contents (16 chapters)
Title Page
About the Author
About the Reviewers
Customer Feedback

Introduction to Oraclize

Oraclize is a service that aims to enable smart contracts to access data from other blockchains and the World Wide Web. This service is currently live on bitcoin and Ethereum's testnet and mainnet. What makes Oraclize so special is that you don't need to trust it because it provides proof of authenticity of all data it provides to smart contracts.

In this chapter, our aim is to learn how Ethereum smart contracts can use the Oraclize service to fetch data from the World Wide Web.

How does it work?

Let's look at the process by which an Ethereum smart contract can fetch data from other blockchains and the World Wide Web using Oraclize.

To fetch data that exists outside of the Ethereum blockchain, an Ethereum smart contract needs to send a query to Oraclize, mentioning the data source (representing where to fetch the data from) and the input for the data source (representing what to fetch).

Sending a query to Oraclize Oraclize means sending a contract call (that is, an internal...