Ethereum: Asset tokenization with Embark

TLDR:

• You’ll build a simple contract in Embark that tokenizes assets with a fixed supply of 1,000 tokens.
• You’ll set a price of 0.1 ether per token and let anyone exchange ether for asset tokens on Sepolia.
• You’ll use Chainstack to deploy and run your own Sepolia node, and Geth to manage your accounts.
• You’ll confirm everything works by testing the contract with Embark’s Cockpit and by sending ether from MetaMask.

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Main article

This tutorial will guide you through creating a tokenized asset contract and deploying it on Sepolia testnet. For illustration purposes, this contract does the following:

• Creates a total supply of 1,000 tokens specific to the asset.
• Sets the token price to 0.1 ether.
• Let anyone exchange ether for asset tokens. This tutorial uses Embark to test and deploy the contract.

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Prerequisites

• Chainstack account to deploy a reliable Ethereum RPC endpoint for Sepolia testnet.
• Embark to test and deploy the contract.
• Geth to create an Ethereum account that will deploy the contract.
• MetaMask to interact with the contract.

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Overview

To get from zero to an asset tokenization contract running on Sepolia, do the following:

1. With Chainstack, create a public chain project.
2. With Chainstack, deploy a Sepolia testnet node.
3. With Embark, create a project and the contract.
4. With Geth, create a new account.
5. Import the account in MetaMask and fund the account with Sepolia ether.
6. With Embark, deploy the contract through the Sepolia node.
7. With Embark, check the contract with Cockpit.
8. Interact with the contract through MetaMask.

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Step-by-step

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Create a public chain project

See Create a project.

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Deploy a Sepolia node

See Join a public network.

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Get Sepolia testnet ether from a faucet

In your MetaMask, fund each account with Sepolia ether Chainstack’s Sepolia faucet.

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Create an Embark project and the contract

1. Create a new Embark project:
   Shell

   embark new asset
   
   This will create an Embark directory called asset.
2. Change to the contracts directory of the Embark project.
3. Create an AssetTokenized.sol file in the contracts directory:
   solidity

   pragma solidity = 0.5.0;
   
   contract AssetTokenized{
   uint public supply;
   uint public pricePerEth;
   mapping( address => uint ) public balance;
   
   constructor() public {
       supply = 1000;                    // There are a total of 1000 tokens for this asset
       pricePerEth = 100000000000000000; // One token costs 0.1 ether
     }
   
     function check() public view returns(uint) {
       return balance[msg.sender];
     }
   
     function () external payable {
       balance[msg.sender] += msg.value/pricePerEth; // adds asset tokens to how much ether is sent by the investor
       supply -= msg.value/pricePerEth;              //subtracts the remaining asset tokens from the total supply
     }
   }
   

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Create an Ethereum account

You will use this account to deploy the contract.

1. Create the account:
   Shell

   geth account new
   
2. Check the path to the keystore file created for the new account:
   Shell

   geth account list
   

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Import the account in MetaMask and fund the account

1. In MetaMask, click Import Account > JSON File.
2. Select the keystore file that you created earlier.
3. Fund the account with Sepolia ether.

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Deploy the contract

1. In your Embark project directory, change to config.
2. Append contracts.js with the following configuration:
   JavaScript

   chainstack: {
     deployment:{
       accounts: [
           {
             privateKeyFile:"//root/.ethereum/keystore/UTC--2019-08-01T07-24-17.754471456Z- -73236c8d8aaee5263e8a32c71171030dd7a3e8e6",
             password:"PASSWORD"
           }
       ],
       host:"YOUR_CHAINSTACK_ENDPOINT",
       port:false,
       protocol:"https",
       type:"rpc"
     },
     dappConnection: [
       "$WEB3",  // uses pre-existing Web3 object if available (e.g in Mist)
       "ws://localhost:8546",
       "<http://localhost:8545>"
     ],
     gas: "auto",
   }
   
   where
   • //root/.ethereum/keystore/... — the location of the keystore file
   • PASSWORD — the password you provided when creating the Ethereum account with Geth
   • YOUR_CHAINSTACK_ENDPOINT — your Chainstack node endpoint. See also View node access and credentials.
3. Deploy the contract with Embark:
   Shell

   embark run chainstack
   
   where chainstack — the argument from the configuration file contracts.js This will deploy the contract on Sepolia.

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Check the contract with Cockpit

On contract deployment, Embark runs Cockpit which is a front-end application to test the contract. In your browser, open: <http://localhost:55555/explorer/contracts/CONTRACT_NAME> where CONTRACT_NAME — the name of your contract. In this tutorial, the path is <http://localhost:55555/explorer/contracts/AssetTokenized>. This will also display the contract address in the Deployed at line. Test the contract by calling:

• supply() — to check the remaining supply of tokens on the contract.
• check() — to check the amount of tokens owned by the Ethereum address you are using to call the contract.
• pricePerEth() — to check the token price in wei.

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Interact with the contract

1. In MetaMask, send an amount of Sepolia ether to the contract address.
2. In Cockpit, call the contract functions supply() and check() after a few seconds to see a change in values returned.