Arhitektura modernih web aplikacija – Deo 5: Mikroservisna arhitektura – dizajn i izazovi

Frontend servis → React
Backend servis → Node.js
Baza servis → PostgreSQL

import CircuitBreaker from 'opossum';

const breaker = new CircuitBreaker(async (userId: number) => {
  const res = await fetch(`http://payment-service/charge/${userId}`);
  if (!res.ok) throw new Error('Payment failed');
  return res.json();
}, {
  timeout: 3000,
  errorThresholdPercentage: 50,
  resetTimeout: 30000
});

breaker.fallback(() => ({ status: 'degraded', message: 'Try later' }));

// Korišćenje
const result = await breaker.fire(userId);

version: '3.8'
services:
  user-service:
    build: ./services/user
    ports: ["3001:3000"]
    environment:
      - DB_URL=postgresql://postgres:pass@db:5432/users
    depends_on: [db, rabbitmq]

  order-service:
    build: ./services/order
    ports: ["3002:3000"]
    depends_on: [rabbitmq, db]

  payment-service:
    build: ./services/payment
    ports: ["3003:3000"]
    depends_on: [rabbitmq]

  rabbitmq:
    image: rabbitmq:3-management
    ports: ["5672:5672", "15672:15672"]

  db:
    image: postgres:15
    environment:
      POSTGRES_PASSWORD: pass
      POSTGRES_MULTIPLE_DATABASES: users,orders
    volumes:
      - postgres_data:/var/lib/postgresql/data

volumes:
  postgres_data:

// user-service/src/events.ts
import amqplib from 'amqplib';

const conn = await amqplib.connect('amqp://rabbitmq');
const channel = await conn.createChannel();

await channel.assertExchange('user.events', 'fanout');

export const publishUserCreated = (user: any) => {
  channel.publish('user.events', '', Buffer.from(JSON.stringify({
    type: 'UserCreated',
    user
  })));
};

// notification-service/src/consumer.ts
channel.consume('user_queue', async (msg) => {
  if (msg) {
    const event = JSON.parse(msg.content.toString());
    if (event.type === 'UserCreated') {
      await sendWelcomeEmail(event.user.email);
    }
    channel.ack(msg);
  }
});