Expiration Policy

Overview

An expiration policy puts a hard time limit on how long a queue message may sit unconsumed. It solves a different problem than a dead-letter policy — this isn't about messages that fail processing, it's about messages that go stale: a price quote, a one-time code, a cache-invalidation signal, where late delivery is actively wrong, not just delayed. Instead of every consumer re-checking timestamps itself, the deadline lives on the message and the broker enforces it.

At the API level, policy: { expirationSeconds: 30 } attaches a per-message TTL when you build the message, and the clock starts the moment the broker accepts it via sendQueueMessage, not when a consumer picks it up. Let the TTL elapse unconsumed and the broker silently removes it — a later poll just comes back empty, no error, no trace.

Gotchas: expiration is silent — no DLQ routing, no event, just a message that vanishes — so pair it with monitoring if you need visibility into how much work is being dropped. The timer starts at send time, not when a consumer picks up the work, so a message can expire mid-backlog even while a consumer is actively polling. And setting the TTL too short for your real consumer lag just turns ordinary slowness into silent data loss.

Prerequisites

• KubeMQ server running on localhost:50000
• Node.js SDK installed (npm install kubemq-js)

Code

import { KubeMQClient, createQueueMessage } from 'kubemq-js';

async function main() {
  const client = await KubeMQClient.create({
    address: 'localhost:50000',
    clientId: 'js-queues-stream-expiration-policy-client',
  });

  try {
    const result = await client.sendQueueMessage(
      createQueueMessage({
        channel: 'js-queues-stream.expiration-policy',
        body: 'this message expires in 30 seconds',
        policy: { expirationSeconds: 30 },
      }),
    );

    console.log('Sent message ID:', result.messageId);
    const expiresAt =
      result.expirationAt instanceof Date && !isNaN(result.expirationAt.getTime())
        ? result.expirationAt.toISOString()
        : 'N/A';
    console.log('Expires at:', expiresAt);
  } finally {
    await client.close();
  }
}

main().catch(console.error);

How It Works

• policy: { expirationSeconds: 30 } sets a TTL on the message; if no consumer receives it within 30 seconds, the server automatically discards it.
• result.expirationAt is a Date confirming the expiry deadline — the instanceof Date && !isNaN(...) guard handles older server versions that may not set it.
• Unlike dead-letter routing, expired messages are simply discarded — there is no DLQ involved unless you also set maxReceiveQueue.
• This pattern is useful for time-sensitive work (e.g., alerts, cache invalidation) where processing a stale message is worse than missing it.

Related

• Pattern overview
• Node.js SDK Reference
• Send & Receive
• Ack All