• Creating a payment Transaction
• Loading an account’s transaction history
• Streaming payment events

Creating a payment transaction

The @digitalbits-blockchain/xdb-digitalbits-sdk exposes the TransactionBuilder class from @digitalbits-blockchain/xdb-digitalbits-base. There are more examples of building transactions here. All those examples can be signed and submitted to DigitalBits in a similar manner as is done below.

In this example, the destination account must exist. The example is written using modern Javascript, but await calls can also be rendered with promises.

// Create, sign, and submit a transaction using JS DigitalBits SDK.

// Assumes that you have the following items:
// 1. Secret key of a funded account to be the source account
// 2. Public key of an existing account as a recipient
//    These two keys can be created and funded by the friendbot at
//    https://laboratory.livenet.digitalbits.io/ under the heading "Quick Start: Test Account"
// 3. Access to JS DigitalBits SDK (https://github.com/xdbfoundation/xdb-digitalbits-sdk)
//    either through Node.js or in the browser.

// This code can be run in the browser at https://laboratory.livenet.digitalbits.io/
// That site exposes a global DigitalBitsSdk object you can use.
// To run this code in the Chrome, open the console tab in the DevTools.
// The hotkey to open the DevTools console is Ctrl+Shift+J or (Cmd+Opt+J on Mac).
const DigitalBitsSdk = require('@digitalbits-blockchain/xdb-digitalbits-sdk');

// The source account is the account we will be signing and sending from.
const sourceSecretKey = 'SCZANGBA5YHTNYVVV4C3U252E2B6P6F5T3U6MM63WBSBZATAQI3EBTQ4';

// Derive Keypair object and public key (that starts with a G) from the secret
const sourceKeypair = DigitalBitsSdk.Keypair.fromSecret(sourceSecretKey);
const sourcePublicKey = sourceKeypair.publicKey();

const receiverPublicKey = 'GAIRISXKPLOWZBMFRPU5XRGUUX3VMA3ZEWKBM5MSNRU3CHV6P4PYZ74D';

// Configure DigitalBitsSdk to talk to the frontier instance hosted by DigitalBits.io
// To use the live network, set the hostname to 'frontier.livenet.digitalbits.io'
const server = new DigitalBitsSdk.Server('https://frontier.testnet.digitalbits.io');

(async function main() {
  // Transactions require a valid sequence number that is specific to this account.
  // We can fetch the current sequence number for the source account from Frontier.
  const account = await server.loadAccount(sourcePublicKey);


  // Right now, there's one function that fetches the base fee.
  // In the future, we'll have functions that are smarter about suggesting fees,
  // e.g.: `fetchCheapFee`, `fetchAverageFee`, `fetchPriorityFee`, etc.
  const fee = await server.fetchBaseFee();


  const transaction = new DigitalBitsSdk.TransactionBuilder(account, {
      fee,
      // Uncomment the following line to build transactions for the live network. Be
      // sure to also change the frontier hostname.
      // networkPassphrase: DigitalBitsSdk.Networks.PUBLIC,
      networkPassphrase: DigitalBitsSdk.Networks.TESTNET
    })
    // Add a payment operation to the transaction
    .addOperation(DigitalBitsSdk.Operation.payment({
      destination: receiverPublicKey,
      // The term native asset refers to nibbs
      asset: DigitalBitsSdk.Asset.native(),
      // Specify 350.1234567 nibbs. Nibbs are divisible to seven digits past
      // the decimal. They are represented in JS DigitalBits SDK in string format
      // to avoid errors from the use of the JavaScript Number data structure.
      amount: '350.1234567',
    }))
    // Make this transaction valid for the next 30 seconds only
    .setTimeout(30)
    // Uncomment to add a memo (https://developers.digitalbits.io/guides/concepts/transactions.html)
    // .addMemo(DigitalBitsSdk.Memo.text('Hello world!'))
    .build();

  // Sign this transaction with the secret key
  // NOTE: signing is transaction is network specific. Test network transactions
  // won't work in the public network. To switch networks, use the Network object
  // as explained above (look for DigitalBitsSdk.Network).
  transaction.sign(sourceKeypair);

  // Let's see the XDR (encoded in base64) of the transaction we just built
  console.log(transaction.toEnvelope().toXDR('base64'));

  // Submit the transaction to the Frontier server. The Frontier server will then
  // submit the transaction into the network for us.
  try {
    const transactionResult = await server.submitTransaction(transaction);
    console.log(JSON.stringify(transactionResult, null, 2));
    console.log('\nSuccess! View the transaction at: ');
    console.log(transactionResult._links.transaction.href);
  } catch (e) {
    console.log('An error has occured:');
    console.log(e);
  }
})();

Loading an account’s transaction history

Let’s say you want to look at an account’s transaction history. You can use the transactions() command and pass in the account address to forAccount as the resource you’re interested in.

const DigitalBitsSdk = require('@digitalbits-blockchain/xdb-digitalbits-sdk')
const server = new DigitalBitsSdk.Server('https://frontier.testnet.digitalbits.io');
const accountId = 'GBBORXCY3PQRRDLJ7G7DWHQBXPCJVFGJ4RGMJQVAX6ORAUH6RWSPP6FM';

server.transactions()
    .forAccount(accountId)
    .call()
    .then(function (page) {
        console.log('Page 1: ');
        console.log(page.records);
        return page.next();
    })
    .then(function (page) {
        console.log('Page 2: ');
        console.log(page.records);
    })
    .catch(function (err) {
        console.log(err);
    });

Streaming payment events

@digitalbits-blockchain/xdb-digitalbits-sdk provides streaming support for Frontier endpoints using EventSource. You can pass a function to handle any events that occur on the stream.

Try submitting a transaction (via the guide above) while running the following code example.

const DigitalBitsSdk = require('@digitalbits-blockchain/xdb-digitalbits-sdk')
const server = new DigitalBitsSdk.Server('https://frontier.testnet.digitalbits.io');

// Get a message any time a payment occurs. Cursor is set to "now" to be notified
// of payments happening starting from when this script runs (as opposed to from
// the beginning of time).
const es = server.payments()
  .cursor('now')
  .stream({
    onmessage: function (message) {
      console.log(message);
    }
  })

For more on streaming events, please check out the Frontier documentation and this guide to server-sent events.