kafka-pub-sub/examples/ecommerce/producer.js

Enterprise-grade Kafka publish/subscribe library for Node.js — producer pool, batch sending, DLQ, SSL/SASL, multi-broker, and real-world industry examples.

/**
 * E-Commerce Order Pipeline — Producer
 *
 * Simulates a checkout service that fires events as a customer places an order.
 *
 * Event flow:
 *   [Checkout] → order.placed
 *              → inventory.reserve  (after stock is confirmed)
 *              → payment.charge     (after reservation)
 *              → fulfillment.ship   (after payment clears)
 *
 * In a real system each of these would be produced by separate microservices.
 * Here they are shown in sequence to illustrate the saga pattern.
 *
 * Run:
 *   cp ../../.env.example ../../.env   # set KAFKA_BROKER_URLS etc.
 *   node examples/ecommerce/producer.js
 */

require('dotenv').config({ path: require('path').resolve(__dirname, '../../.env') });

const { ProduceEvent } = require('../../index');

const TOPICS = {
  ORDER_PLACED: 'order.placed',
  INVENTORY_RESERVE: 'inventory.reserve',
  PAYMENT_CHARGE: 'payment.charge',
  FULFILLMENT_SHIP: 'fulfillment.ship',
};

const generateOrderId = () => `ORD-${Date.now()}`;
const generateCorrelationId = () => `CORR-${Math.random().toString(36).slice(2, 10).toUpperCase()}`;

/**
 * Simulates a complete order saga: place → reserve → pay → ship.
 */
async function runOrderSaga() {
  const orderId = generateOrderId();
  const correlationId = generateCorrelationId();
  const traceHeaders = {
    'correlation-id': correlationId,
    'x-source': 'checkout-service',
    'x-tenant': 'acme-corp',
  };

  // eslint-disable-next-line no-console
  const log = (...args) => console.log(`[${new Date().toISOString()}]`, ...args);

  log(`Starting order saga for ${orderId} (correlation: ${correlationId})`);

  // 1. Order placed
  await ProduceEvent(
    TOPICS.ORDER_PLACED,
    'ORDER_PLACED',
    {
      orderId,
      customerId: 'CUST-42',
      items: [
        { sku: 'SKU-WIDGET-100', qty: 2, unitPrice: 29.99 },
        { sku: 'SKU-GADGET-200', qty: 1, unitPrice: 89.99 },
      ],
      currency: 'USD',
      total: 149.97,
      shippingAddress: {
        line1: '123 Main St',
        city: 'San Francisco',
        state: 'CA',
        zip: '94102',
        country: 'US',
      },
    },
    traceHeaders,
    { correlationId }
  );
  log(`✓ Produced: ORDER_PLACED → ${TOPICS.ORDER_PLACED}`);

  // 2. Inventory reservation request
  await ProduceEvent(
    TOPICS.INVENTORY_RESERVE,
    'INVENTORY_RESERVE',
    {
      orderId,
      reservations: [
        { sku: 'SKU-WIDGET-100', qty: 2, warehouseId: 'WH-WEST-01' },
        { sku: 'SKU-GADGET-200', qty: 1, warehouseId: 'WH-EAST-03' },
      ],
      expiresAt: new Date(Date.now() + 15 * 60 * 1000).toISOString(), // 15 min hold
    },
    { ...traceHeaders, 'x-source': 'inventory-service' },
    { correlationId, partitionKey: orderId }
  );
  log(`✓ Produced: INVENTORY_RESERVE → ${TOPICS.INVENTORY_RESERVE}`);

  // 3. Payment charge request
  await ProduceEvent(
    TOPICS.PAYMENT_CHARGE,
    'PAYMENT_CHARGE',
    {
      orderId,
      customerId: 'CUST-42',
      paymentMethodId: 'pm_3Nbz7g2eZvKYlo2C1wWR45Sz', // Stripe token
      amount: 14997, // in cents
      currency: 'usd',
      metadata: { orderId, correlationId },
    },
    { ...traceHeaders, 'x-source': 'payment-service' },
    { correlationId, partitionKey: 'CUST-42' } // partition by customer for ordering
  );
  log(`✓ Produced: PAYMENT_CHARGE → ${TOPICS.PAYMENT_CHARGE}`);

  // 4. Fulfillment / shipment trigger
  await ProduceEvent(
    TOPICS.FULFILLMENT_SHIP,
    'FULFILLMENT_SHIP',
    {
      orderId,
      fulfillmentItems: [
        { sku: 'SKU-WIDGET-100', qty: 2, warehouseId: 'WH-WEST-01' },
        { sku: 'SKU-GADGET-200', qty: 1, warehouseId: 'WH-EAST-03' },
      ],
      shippingCarrier: 'UPS',
      shippingService: 'GROUND',
      estimatedDelivery: new Date(Date.now() + 5 * 24 * 60 * 60 * 1000).toISOString(),
    },
    { ...traceHeaders, 'x-source': 'fulfillment-service' },
    { correlationId }
  );
  log(`✓ Produced: FULFILLMENT_SHIP → ${TOPICS.FULFILLMENT_SHIP}`);

  log(`Order saga complete for ${orderId}`);

  await ProduceEvent.disconnect();
}

runOrderSaga().catch((err) => {
  // eslint-disable-next-line no-console
  console.error('Order saga failed:', err);
  process.exit(1);
});