Book Image

Hands-On Blockchain with Hyperledger

By : Nitin Gaur, Luc Desrosiers, Venkatraman Ramakrishna, Petr Novotny, Salman A. Baset, Anthony O'Dowd
Book Image

Hands-On Blockchain with Hyperledger

By: Nitin Gaur, Luc Desrosiers, Venkatraman Ramakrishna, Petr Novotny, Salman A. Baset, Anthony O'Dowd

Overview of this book

Blockchain and Hyperledger technologies are hot topics today. Hyperledger Fabric and Hyperledger Composer are open source projects that help organizations create private, permissioned blockchain networks. These find application in finance, banking, supply chain, and IoT among several other sectors. This book will be an easy reference to explore and build blockchain networks using Hyperledger technologies. The book starts by outlining the evolution of blockchain, including an overview of relevant blockchain technologies. You will learn how to configure Hyperledger Fabric and become familiar with its architectural components. Using these components, you will learn to build private blockchain networks, along with the applications that connect to them. Starting from principles first, you’ll learn to design and launch a network, implement smart contracts in chaincode and much more. By the end of this book, you will be able to build and deploy your own decentralized applications, handling the key pain points encountered in the blockchain life cycle.
Table of Contents (20 chapters)
Title Page
Copyright and Credits
Packt Upsell
Foreword
Contributors
Preface
Index

Creating a chaincode


We are now ready to start to implementing our chaincode, which we will program in the Go language. There are several IDEs available that provide support for Go. Some of the better IDEs include Atom, Visual Studio Code, and many more. Whatever environment you opt for will work with our example.

The chaincode interface

Every chaincode must implement the Chaincode interface, whose methods are called in response to the received transaction proposals. The Chaincode interface defined in the SHIM package is shown in the following listing:

type Chaincode interface { 
    Init(stub ChaincodeStubInterface) pb.Response 
    Invoke(stub ChaincodeStubInterface) pb.Response 
} 

As you can see, the Chaincode type defines two functions: Init and Invoke.

Both functions have a single argument, stub, of the type ChaincodeStubInterface.

The stub argument is the main object that we will use when implementing the chaincode functionality, as it provides functions for accessing and modifying the...