Introduction

This tutorial aims to introduce you to the Hyperledger Framework, an open-source blockchain technology that is designed to support the development of enterprise-grade distributed ledgers. We will explore how to set up and use the Hyperledger Framework to create business networks.

By the end of this tutorial, you will:
- Understand the basic principles of the Hyperledger Framework
- Learn how to install and set up the Hyperledger Framework
- Learn how to create a simple business network using Hyperledger

Prerequisites: Familiarity with blockchain concepts and a basic understanding of coding principles.

Step-by-Step Guide

What is Hyperledger?

Hyperledger is a global collaboration hosted by The Linux Foundation. It's an umbrella project of open-source blockchains and related tools, designed to support the collaborative development of blockchain-based distributed ledgers.

How to Install Hyperledger

1. Ensure you have the following prerequisites: Docker, Docker Compose, Node.js, npm, Python, and Git.
2. Clone the Hyperledger Fabric samples repository:

$ git clone https://github.com/hyperledger/fabric-samples.git

1. Run the download script:

$ cd fabric-samples
$ ./scripts/bootstrap.sh

Creating a Business Network

1. Navigate to the fabric-samples/chaincode directory.
2. Here, you can create your own chaincode directory and write your chaincode.

Code Examples

Creating a Chaincode

1. Create a new directory, mychaincode, and navigate into it.
2. Create a new file, chaincode.js.

$ mkdir mychaincode
$ cd mychaincode
$ touch chaincode.js

1. Write your chaincode in chaincode.js.

'use strict';

const { Contract } = require('fabric-contract-api');

class MyChaincode extends Contract {

    async initLedger(ctx) {
        console.info('============= START : Initialize Ledger ===========');
        // Initialize ledger with data
        console.info('============= END : Initialize Ledger ===========');
    }

    async queryData(ctx, dataId) {
        const dataAsBytes = await ctx.stub.getState(dataId); 
        if (!dataAsBytes || dataAsBytes.length === 0) {
            throw new Error(`${dataId} does not exist`);
        }
        console.log(dataAsBytes.toString());
        return dataAsBytes.toString();
    }

    // Other chaincode functions...
}

module.exports = MyChaincode;

In the initLedger function, you would usually initialize your ledger with some data. In the queryData function, you can query data from your ledger using a unique ID.

Summary

Congratulations! You've now learned what the Hyperledger Framework is, how to install it, and how to create a basic business network with it. For further learning, consider exploring more complex chaincode development and Hyperledger's various tools and libraries.

Practice Exercises

1. Exercise 1: Install the Hyperledger Framework and initialize a basic business network.
2. Exercise 2: Modify the given chaincode to include a function for adding data to the ledger.
3. Exercise 3: Modify the given chaincode to include a function for updating existing data in the ledger.

Solutions:

Exercise 1: The steps provided in the "How to Install Hyperledger" section should guide you through this process.

Exercise 2 and 3: Here's how you might add these functions:

    async addData(ctx, dataId, value) {
        console.info('============= START : Add data ===========');
        const data = { value };
        await ctx.stub.putState(dataId, Buffer.from(JSON.stringify(data)));
        console.info('============= END : Add data ===========');
    }

    async updateData(ctx, dataId, newValue) {
        console.info('============= START : Update data ===========');
        const dataAsBytes = await ctx.stub.getState(dataId);
        if (!dataAsBytes || dataAsBytes.length === 0) {
            throw new Error(`${dataId} does not exist`);
        }
        const data = JSON.parse(dataAsBytes.toString());
        data.value = newValue;
        await ctx.stub.putState(dataId, Buffer.from(JSON.stringify(data)));
        console.info('============= END : Update data ===========');
    }

Keep practicing and exploring more functionalities offered by the Hyperledger Framework!