Instructions

Reference links

Create an IoTeX Developer account

1. Add the IoTeX Testnet RPC to Metamask
2. Create a “bike owner” account in Metamask
3. Login to developers.iotex.io
4. In your dashboard, connect Metamask and claim some IOTX Test tokens
5. Copy your account private key (ideally, the deployer account should not be the bike owner, I'm using the same account for brevity).

Create the template project

npx [email protected] bike-sharing  

 \ \/ \/ /  ___/ \__  \ \____ \\____ \ 
   \     /\___ \   / __ \|  |_> >  |_> >
    \/\_//____  > (____  /   __/|   __/ 
              \/       \/|__|   |__|      


✔ 💰 include an erc20 token template? (Y/n) · true
✔ 🖼️  include an erc721 token template? (Y/n) · false
✔ 👤 include an onchain device registration and binding template? (Y/n) · false
✔ 🤖 include a device simulator template? (Y/n) · true



Deploy the ERC20 token

cd bike-sharing


code .


echo IOTEX_PRIVATE_KEY=61f4ef093be2d4e362bec0f65b1be3db6642a749942f330b2a659c71badb982b > .env


npm run deploy:testnet


Create the W3bstream logic

Clean the applet template

1. Rename erc20.ts to handle_new_ride.ts
2. Rename handler to handle_new_ride.ts
3. Delete unused functions
4. Empty the main handler

Code the applet

import { GetDataByRID, JSON, Log, SendTx } from "@w3bstream/wasm-sdk";

import { buildTxData } from "../utils/build-tx";


const MINT_FUNCTION_ADDR = "40c10f19";
const CHAIN_ID = 4690;
const TOKEN_CONTRACT_ADDRESS = "0xF50018BdeD7cb3DaC940A34ebb8DDA87134FAf01";

// This handler is called when a ride is completed.
// In this case the Bike will send a message like this
// {
  // bike_owner: "0x1234567890123456789012345678901234567890",
  // ride_duration: 123,
  // ride_distance: 123,
// }
export function handle_ride_completed(rid: i32): i32 {
  Log("--- New ride completed message received ---");
  
  const message = GetDataByRID(rid);
  Log("Device message: " + message);

  const message_json = JSON.parse(message) as JSON.Obj;

  let bike_owner = message_json.getString("bike_owner");
  if (bike_owner == null) { assert(false, "bike_owner field not found");  return 1;}

  let ride_duration = message_json.getInteger("ride_duration");
  if (ride_duration == null) { assert(false, "ride_duration field not found"); return 1;}

  let ride_distance = message_json.getInteger("ride_distance");
  if (ride_distance == null) { assert(false, "ride_distance field not found"); return 1;}

  // Let's now calculat the value of this ride
  // We want to give a cost per km of 0.1 tokens
  // and a cost per minute of 0.01 tokens
  const cost_per_km: number = 1 / 1000;
  const cost_per_minute: number = 0.1 / 60;
  const ride_cost: number = 
    (cost_per_km * f64(ride_distance.valueOf())) + 
    (cost_per_minute * f64(ride_duration.valueOf()));

  Log("Ride cost: " + ride_cost.toString());

  // As the project owners we want to keep a fee of 10% of the ride cost
  const fee: number = ride_cost * 0.1;

  // So let's calculate the amount of tokens to send to the bike owner
  const TOKEN_AMOUNT = ride_cost - fee;

  Log("Token amount: " + TOKEN_AMOUNT.toString());

  // and finally send the payment to the bike owner
  mintRewards<number>(bike_owner.valueOf(), TOKEN_AMOUNT);

  return 0;
}

function mintRewards<T>(ownerAddress: string, amount: T): void {
  const txData = buildTxData(MINT_FUNCTION_ADDR, ownerAddress, amount);
  const res = SendTx(CHAIN_ID, TOKEN_CONTRACT_ADDRESS, "0", txData);
  Log("Send tx result:" + res);
}



Build the applet

npm run asbuild


Deploy the applet as a WS Project

Create a new device

Wire the event handler

Send a test message

{
    "bike_owner": "0x2C37a2cBcFacCdD0625b4E3151d6260149eE866B",
    "ride_duration": 3600,
    "ride_distance": 15000
}


Introduce Env Variables

const TOKEN_CONTRACT = GetEnv("TOKEN_CONTRACT")


Code the simulator

cd simulator
npm install --save w3bstream-client-js
npm install axios


import { W3bstreamClient } from "w3bstream-client-js";

const URL = "http_route";
const API_KEY = "api_key";

const client = new W3bstreamClient(URL, API_KEY);

const header = {
  deviceId: "device_id",
  eventType: "event_type",
};

// const payload = Buffer.from("test data", "utf8"); or
const payload = {
  data: "data",
};

main();

async function main() {
  try {
    const res = await client.publish(header, payload);

    console.log(JSON.stringify(res.data, null, 2));
  } catch (error) {
    console.error(error);
  }
}




    bike_owner: "0x2C37a2cBcFacCdD0625b4E3151d6260149eE866B",
    ride_duration: 3600,
    ride_distance: 15000



Build

tsc
node dist/index.js