ict-architecture

Labo 09: Transactional Outbox

Implementatie van een Message Relay in Node.js die periodiek onverzonden berichten naar RabbitMQ stuurt.

Uitvoeren

node relay.js

Start de message relay.

Bestanden & Configuraties

relay.js

javascript

const mysql = require('mysql2/promise');
const amqp = require('amqplib');
async function relayMessages() {
  const connection = await mysql.createConnection({ host: 'localhost', user: 'root', database: 'microservices' });
  const channel = await (await amqp.connect('amqp://localhost')).createChannel();
  setInterval(async () => {
    const [rows] = await connection.execute('SELECT * FROM outbox WHERE is_sent = FALSE');
    for (const row of rows) {
      channel.publish('domain_events', row.type, Buffer.from(JSON.stringify(row.payload)));
      if (Math.random() < 0.1) process.exit(1); // Simuleer 10% falen
      await connection.execute('UPDATE outbox SET is_sent = TRUE WHERE id = ?', [row.id]);
    }
  }, 10000);
} 
relayMessages();

Periodieke controle op de outbox tabel.

outbox.sql

sql

CREATE TABLE outbox (
    id INT AUTO_INCREMENT PRIMARY KEY,
    aggregate_type VARCHAR(255),
    aggregate_id VARCHAR(255),
    type VARCHAR(255),
    payload JSON,
    is_sent BOOLEAN DEFAULT FALSE,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Schema voor de outbox tabel.