Cosmos Africa Developer Tutorial: Building a Simple Blockchain Application with Code Snippets

Introduction: In this tutorial, we will walk through the process of building a simple blockchain application using the Cosmos SDK. The Cosmos SDK provides a robust framework for developers to create their custom blockchains with ease. We will cover the essential steps, including setting up the development environment, defining a basic blockchain module, and testing our application. Let’s get started!

Prerequisites:

1. Basic understanding of blockchain concepts and the Go programming language.
2. Go programming language installed on your machine (https://golang.org/dl/).
3. A text editor or integrated development environment (IDE) for writing Go code.

Install the Cosmos SDK by running the following command in your terminal:

go get github.com/cosmos/cosmos-sdk

Create a new directory for your blockchain application:

mkdir myblockchainapp
cd myblockchainapp

Initialize a new Go module:

go mod init myblockchainapp

Step 2: Defining the Basic Blockchain Module

1. Create a new file named app.go in the myblockchainapp directory.
2. Open app.go and import the necessary packages:

package main

import (
 "fmt"
 "os"

 "github.com/cosmos/cosmos-sdk/x/bank"
 "github.com/tendermint/tendermint/libs/cli"
 "github.com/spf13/cobra"
 "github.com/spf13/viper"
 "github.com/tendermint/tendermint/libs/log"
 "github.com/cosmos/cosmos-sdk/types/module"
 sdk "github.com/cosmos/cosmos-sdk/types"
 abci "github.com/tendermint/tendermint/abci/types"
 tmtypes "github.com/tendermint/tendermint/types"
 "github.com/cosmos/cosmos-sdk/x/auth"
 "github.com/cosmos/cosmos-sdk/x/genutil"
 "github.com/cosmos/cosmos-sdk/x/staking"
)

Define the main function:

func main() {
 cobra.EnableCommandSorting = false
 cdc := app.MakeCodec()

 ctx := server.NewDefaultContext()
 cobra.SetupRootCommand(ctx, nil)
 app.SetName("myblockchainapp")

 rootCmd := &cobra.Command{
  Use:               "appcli",
  Short:             "MyBlockchainApp CLI",
  PersistentPreRunE: server.PersistentPreRunEFn(ctx),
 }

 app.ModuleBasics.RegisterLegacyAminoCodec(cdc)
 rootCmd.PersistentFlags().String(cli.HomeFlag, app.DefaultNodeHome, "node home directory")

 rootCmd.AddCommand(
  genutil.InitCmd(ctx, cdc, app.ModuleBasics, app.DefaultNodeHome),
  genutil.CollectGenTxsCmd(ctx, cdc, auth.GenesisAccountIterator{}, app.DefaultNodeHome),
  genutil.MigrateGenesisCmd(ctx, cdc),
  genutil.GenTxCmd(ctx, cdc, app.ModuleBasics, staking.AppModuleBasic{}, bank.GenesisBalancesIterator{}, app.DefaultNodeHome, app.DefaultCLIHome),
  genutil.ValidateGenesisCmd(ctx, cdc, app.ModuleBasics),
  AddGenesisAccountCmd(ctx, cdc),
  AddGenesisVestingAccountCmd(ctx, cdc),
  GetGenesisCmd(ctx, cdc),
  tmtypes.GenTxCmd(ctx, cdc),
  tmtypes.GenValidatorCmd(ctx, cdc, staking.AppModuleBasic{}),
  // more commands...
 )

 server.AddCommands(ctx, cdc, rootCmd, newApp, exportAppStateAndTMValidators)

 executor := cli.PrepareBaseCmd(rootCmd, "MYAPP", app.DefaultNodeHome)
 err := executor.Execute()
 if err != nil {
  fmt.Printf("Error: %s\n", err)
  os.Exit(1)
 }
}

Step 3: Building and Testing the Blockchain Application

Build the application using the following command:

go build -o myblockchainapp

Initialize the blockchain:

./myblockchainapp init mynode --chain-id=mychain

Create a new validator for staking:

./myblockchainapp add-genesis-account YOUR_VALIDATOR_ADDRESS 1000stake,1000000000foo
./myblockchainapp gentx YOUR_VALIDATOR_ADDRESS 1000000000foo --chain-id=mychain
./myblockchainapp collect-gentxs

Start the blockchain node:

./myblockchainapp start

we have just successfully built and tested a simple blockchain application using the Cosmos SDK. This tutorial only scratches the surface of what you can achieve with the Cosmos SDK. I encourage you to explore more advanced features and modules to build powerful and scalable decentralized applications tailored to your specific needs.

Conclusion

The Cosmos SDK provides a developer-friendly environment for creating custom blockchains and decentralized applications. By following this tutorial, you have gained a foundational understanding of building a basic blockchain application with the Cosmos SDK. Empowered with this knowledge, you can now explore the vast potential of blockchain technology and contribute to the innovative landscape of decentralized solutions in Africa and beyond.

LETS CODE AFRICA

Happy coding!