Building a sidechain with the Klayr SDK

The "Build Blockchain" category contains all the guides related to the development of a blockchain client with the Klayr SDK.

Table of Contents

The "Hello World" client

By the example of the "Hello World" client, it is explained how to build a very simple blockchain client step by step in the following chapters.

Although the example is kept very simple by intention, the Hello World client implements all the most important components, and is therefore a good example to understand the basics of the development of a blockchain client.

The "Hello World" client allows each account to save a greeting message on-chain. It also stores the addresses of senders of the greeting message, in an off-chain database. The following guides each focus on developing a specific part of the Hello client.

  1. Creating a new blockchain client: How to bootstrap a default blockchain client.

  2. Blockchain client configuration: How to create a custom configuration for a blockchain client.

  3. How to create a module: How to create a new module and how to add it to the client. In the example, the HelloModule will contain all on-chain logic related to the Hello message.

    1. How to create a command: How to create a new command and how to add it to a module. In the example, the "Create Hello" command saves Hello messages of accounts, if they send a corresponding transaction.

  4. How to create a plugin: How to create a new plugin and how to add it to the blockchain client.

    1. In the example, the HelloInfoPlugin will save all sent Hello messages, their corresponding sender address, and the corresponding block height of each event in an off-chain database.

    2. It will also expose an endpoint to retrieve the data from the off-chain database.

    3. The plugin will also be configured and based on the configuration, the plugin will sync with the sidechain after regular intervals.

  5. How to create a new genesis block: How to generate a new genesis block for a blockchain.

Complete application code

View the complete sample code of the complete "Hello World" Klayr app on GitHub in the Klayr SDK examples repository.

The following image provides an overview of the "Hello" client:

Hello client overview
Figure 1. Salient features of the Hello Client