Node

Introduction

This tutorial will take you through the basics of creating a Kin enabled app using Node.js.

Requirements

Make sure you have read Getting Started and have the required environment variables

Implementing Kin in your app

1. Install the Kin SDK for Node to your project:

npm install @kinecosystem/kin-sdk-v2
# Or if you use yarn
yarn add @kinecosystem/kin-sdk-v2

2. Create a Node.js app and add the kin.ts class to your app

This class abstracts some calls to Kin's official SDK and is fully usable out of the box. However, you can easily extend it to suite your custom needs.

3. Instantiate a new Kin client

We're creating a new instance of our Kin wrapper and pass in the environment. In this example we'll pick the Test network.

// Set up Kin client
const kin = new Kin(Environment.Test);

Congratulations! You now have a Kin enabled app running!

Making calls to the Kin blockchain

In this example, we're going to create a new wallet for both Alice and Bob by generating new key pair. After the wallet is created, Alice will send a P2P transaction to Bob.

4. Create account for Alice

We create a new private key-pair for Alice, then call into our wrapper to create a new account. After creation, we log out the public address of both the wallet, and the balances

const privateKeyAlice = Kin.generateKey();
const balancesAlice = await kin.createAccount(privateKeyAlice);

console.log(`Public Key Alice    ${privateKeyAlice.publicKey().toBase58()}`);
for (const balance of balancesAlice) {
  console.log(`Token Account Alice ${balance.toBase58()}`);
}

4. Create account for Bob

const privateKeyBob = Kin.generateKey();
const balancesBob = await kin.createAccount(privateKeyBob);

console.log(`Public Key Bob      ${privateKeyBob.publicKey().toBase58()}`);
for (const balance of balancesBob) {
  console.log(`Token Account Bob   ${balance.toBase58()}`);
}

5. Add Helper method

Creating the Account on the Solana Blockchain and later the Kin 'token account', might take a few seconds. To address for this, we will have several 15 seconds sleep periods as it's an easy way to delay things in our code.

We also use this helper method to print the balance after sleeping.

// Helper method to await sleep...
const sleep = (seconds = 1) =>
  new Promise((resolve) => setTimeout(resolve, seconds * 1000));
// Helper method to sleep a bit, then print balance of Alice and Bob
async function sleepAndPrintBalances() {
  console.log("Sleeping for a bit...");
  await sleep(15);
  await kin.getBalance(privateKeyAlice.publicKey()).then((b) => {
    console.log(`Balance for Alice:  ${quarksToKin(b)} Kin`);
  });
  await kin.getBalance(privateKeyBob.publicKey()).then((b) => {
    console.log(`Balance for Bob:    ${quarksToKin(b)} Kin`);
  });
}

// Execute the function one time before moving on so the accounts will be created
await sleepAndPrintBalances();

6. Request Airdrop

We can now request and Airdrop for both of our balances. Note that this is only for the Test network.

In this example we'll request 10 Kin for both Alice and Bob.

console.log("Request Airdrop for Alice");
await kin.requestAirdrop(balancesAlice[0], "10");

console.log("Request Airdrop for Bob");
await kin.requestAirdrop(balancesBob[0], "10");

await sleepAndPrintBalances();

7. Send payment from Alice to Bob

Now we can send a payment from one account to the other.

console.log("Submit P2P Payment from Alice to Bob");
await kin.submitP2P(
  privateKeyAlice,
  privateKeyBob.publicKey(),
  "2",
  "My demo payment"
);

await sleepAndPrintBalances();

8. Use webhooks to listen for events on the blockchain.

Once you have registered your app in getting started, and received confirmation from the Kin foundation, your server can also listen for events generated by your app through webhooks.

Use the server webhook and server events endpoints that you registered in Getting Started. The webhook password you registered authenticates calls automatically.

//listen for different events related to the app
kin.registerEventsHook("webhook_password", "/server_events", (event) => {
  console.log("Event hook received", event);
});

//listen for transactions related to the app
kin.registerSignTxHook(
  "webhook_password",
  "/server_webhook",
  Environment.Test,
  (req, res) => {
    console.log("Sign tx hook received", req, res);
  }
);

Once these webhooks are registered, your server will receive event notifications whenever your app (android or iOS) performs a transaction