🚀 Start Naryo with Hedera

This guide explains how to deploy a local Hedera node and a smart contract that emits events, allowing you to test event consumption in Naryo.

🧰 Requirements

Ensure you have the following installed:

Java 21
Docker & Docker Compose
Node.js 20.19.4 LTS & npm 10.8.2
Hardhat
Git

🎉 Step 0: Prepare your environment

Create a directory for the tutorial, for example: naryo-hedera-tutorial and run the following command:

  mkdir naryo-hedera-tutorial # or whatever name you like
  cd naryo-hedera-tutorial

⚙️ Step 1: Start Hedera Dev Network

The easiest way to start a local Hedera node is using the Hiero Local Node, which supports Hedera networks with minimal setup.

Run the following command to download the setup:
```
npm install @hashgraph/hedera-local -g
```
Once the hedera-local package is installed, run the following command:
```
hedera start
```
This command launches the network using Docker Compose and exposes the following JSON-RPC endpoint: http://localhost:8545

⚠️ Remember to have docker running on your machine.
Use the following pre-funded test account in your deployment scripts:
```
Private Key: 0x105d050185ccb907fba04dd92d8de9e32c18305e097ab41dadda21489a211524
Address:    0x67D8d32E9Bf1a9968a5ff53B87d777Aa8EBBEe69
```
⚠️ Only use this key for local testing. Never use it in production environments.

📦 Step 2: Deploy an ERC-20 Contract that Emits Events

Make sure you are in the tutorial directory before following the steps below.

1. Create a Hardhat project:

mkdir erc20-contract && cd erc20-contract
npm init -y
npm install --save-dev hardhat
npx hardhat init

Choose: “Create a JavaScript project” and accept the defaults.

2. Define your contract:

Install OpenZeppelin contracts:

npm install @openzeppelin/contracts

Create contracts/MyToken.sol:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.28;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract MyToken is ERC20 {
    constructor(uint256 initialSupply) ERC20("MyToken", "MTK") {
        _mint(msg.sender, initialSupply);
    }
}

3. Configure Hardhat to connect to Hedera:

You can use the following hardhat.config.js file:

require("@nomicfoundation/hardhat-toolbox");

/** @type import('hardhat/config').HardhatUserConfig */
module.exports = {
  solidity: "0.8.28",
  defaultNetwork: 'local',
    networks: {
      local: {
        url: 'http://localhost:7546',
        accounts: [
          "0x105d050185ccb907fba04dd92d8de9e32c18305e097ab41dadda21489a211524",
          "0x2e1d968b041d84dd120a5860cee60cd83f9374ef527ca86996317ada3d0d03e7"
        ],
        chainId: 298,
      },
      testnet: {
        url: 'https://testnet.hashio.io/api',
        accounts: [],
        chainId: 296,
      },
    }
};

4. Deploy the contract:

Add a new ignition module ignition/modules/MyToken.js:

const { buildModule } = require("@nomicfoundation/hardhat-ignition/modules");

const INITIAL_SUPPLY = 1000000;

module.exports = buildModule("MyToken", (m) => {
  const initialSupply = m.getParameter("initialSupply", INITIAL_SUPPLY);

  const myToken = m.contract("MyToken", [initialSupply]);

  return { myToken };
});

Then run:

npx hardhat ignition deploy ignition/modules/MyToken.js

The output should look like this:

[ MyToken ] successfully deployed 🚀

Deployed Addresses

MyToken#MyToken - <YOUR_CONTRACT_ADDRESS>

Save the contract address, you will need it later.

🏗️ Step 3: Publish Naryo Modules Locally

Make sure you are in the tutorial directory before following the steps below.

Before generating your testing project, make sure to publish the Naryo modules to your local Maven repository:

git clone https://github.com/LF-Decentralized-Trust-labs/Naryo naryo # skip if already cloned
cd naryo
./gradlew publishToMavenLocal

This is required so that your new project can resolve the Naryo dependencies.

🧬 Step 4: Generate a Naryo Project

Use the Naryo CLI initializer to scaffold your project:

./gradlew :initializer:run --args="--name test-naryo --output <YOUR_TUTORIAL_DIRECTORY>"

Replace <YOUR_TUTORIAL_DIRECTORY> with the path to your tutorial directory.

This will generate a folder test-naryo/ in your tutorial directory with:

Project structure
build.gradle with correct dependencies
Application.java class
application.yml with prefilled node and broadcaster config

ℹ️ You can modify the YAML to use your deployed contract address and filters.

🔧 Step 5: Configure `application.yml`

Make sure you are in the test-naryo/ directory before following the steps below.

Replace the generated file src/main/resources/application.yml to include your Hedera node and contract:

naryo:
  nodes:
    - id: eadc75b2-4217-4018-95af-f67c13058976
      name: hedera-node
      type: HEDERA
      connection:
        type: HTTP
        endpoint:
          url: http://localhost:5551
      interaction:
        type: BLOCK_BASED
        mode: HEDERA_MIRROR_NODE
      subscription:
        type: BLOCK_BASED
        method:
          type: POLL
          interval: 2s
  broadcasting:
    configuration:
      - id: cd1bec0d-2998-46bc-828f-94459d42c17a
        type: HTTP
        endpoint:
          url: http://localhost:8080
    broadcasters:
      - id: cd1bec0d-2998-46bc-828f-94459d43c17b
        configurationId: cd1bec0d-2998-46bc-828f-94459d42c17a
        target:
          type: ALL
          destination: /events
  filters:
    - id: a5605668-7a88-4e5c-b4ee-4a8417b7184d
      name: my-transfer-filter
      type: EVENT
      nodeId: eadc75b2-4217-4018-95af-f67c13058976
      scope: GLOBAL
      specification:
        signature: Transfer(address indexed, address indexed, uint256)

You can also use the RPC-Relay with the Hedera node. Simply replace the node in the following lines:

naryo:
  nodes:
    - id: eadc75b2-4217-4018-95af-f67c13058976
      name: hedera-node
      type: HEDERA
      connection:
        type: HTTP
        endpoint:
          url: http://localhost:7546

📁 Step 6: Expose Event Notifications via HTTP

Make sure you are in the tutorial directory before following the steps below.

Create a new folder for your event receiver script:

mkdir naryo-listener
cd naryo-listener

This script will allow Naryo to forward received events to your local HTTP server.

To observe how Naryo processes and reacts to events, you can expose a simple HTTP endpoint using Node.js and Express.

Create a new file called server.js with the following content:

const express = require('express');
const bodyParser = require('body-parser');

const app = express();
const port = 8080;

app.use(bodyParser.json());

app.post('/events', (req, res) => {
  console.log('✅ Event received:', JSON.stringify(req.body, null, 2));
  res.status(200).send('OK');
});

app.listen(port, () => {
  console.log(`🚀 Event receiver listening at http://localhost:${port}/events`);
});

Install dependencies and start the server:

npm install express body-parser
nohup node server.js > event-receiver.log 2>&1 &

Now every received event will be forwarded and printed in your local Node.js server.

🥪 Step 7: Run the Naryo Application

Go to your generated project folder:
```
cd test-naryo
```
Run the application:
```
./gradlew bootRun
```

Naryo will start and listen to the configured event (Transfer) using polling from your Hedera node.

🪵 Step 8: Check the Naryo listener logs

Open a new terminal window.
Navigate to the naryo-listener/ directory.
Run the following command to monitor incoming events:
```
 tail -f event-receiver.log
```

You should see the event payload printed whenever a Transfer event is emitted from your contract and every mined block.

✅ Verify

You can now verify that Naryo is correctly forwarding events to your local HTTP server.

Make sure you are in the erc20-contract/ directory before following the steps below.

Let's trigger the event from the Hardhat console:

Open a new terminal.
Start the Hardhat console:
```
npx hardhat console --network besu
```
Execute the following commands to interact with your contract (replace DEPLOYED_CONTRACT_ADDRESS if needed):

var token = await ethers.getContractAt("MyToken", DEPLOYED_CONTRACT_ADDRESS);

await token.transfer("0x9ba8c0dF156194706942a86f49081542F13EbF42", 1);

You can run the above commands multiple times to trigger the event.

You should see the output in the Node.js event listener server.

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🚀 Start Naryo with Hedera

🧰 Requirements

🎉 Step 0: Prepare your environment

⚙️ Step 1: Start Hedera Dev Network

📦 Step 2: Deploy an ERC-20 Contract that Emits Events

1. Create a Hardhat project:

2. Define your contract:

3. Configure Hardhat to connect to Hedera:

4. Deploy the contract:

🏗️ Step 3: Publish Naryo Modules Locally

🧬 Step 4: Generate a Naryo Project

🔧 Step 5: Configure `application.yml`

📁 Step 6: Expose Event Notifications via HTTP

🥪 Step 7: Run the Naryo Application

🪵 Step 8: Check the Naryo listener logs

✅ Verify

📚 Resources

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🚀 Start Naryo with Hedera

🧰 Requirements

🎉 Step 0: Prepare your environment

⚙️ Step 1: Start Hedera Dev Network

📦 Step 2: Deploy an ERC-20 Contract that Emits Events

1. Create a Hardhat project:

2. Define your contract:

3. Configure Hardhat to connect to Hedera:

4. Deploy the contract:

🏗️ Step 3: Publish Naryo Modules Locally

🧬 Step 4: Generate a Naryo Project

🔧 Step 5: Configure application.yml

📁 Step 6: Expose Event Notifications via HTTP

🥪 Step 7: Run the Naryo Application

🪵 Step 8: Check the Naryo listener logs

✅ Verify

📚 Resources

🔧 Step 5: Configure `application.yml`