Unreliable Async Processing

How to build reliable async processing in Laravel and Symfony with Ecotone

The Problem You Recognize

You added async processing to handle background work — sending emails, processing payments, syncing data. But now you have new problems:

• Failed jobs disappear silently or retry forever with no visibility
• You can't replay a failed message after fixing the bug — the data is gone
• A duplicate webhook triggers the same handler twice, leading to double charges or duplicate emails
• Going async required touching every handler — adding queue configuration, serialization, and retry logic to each one
• Retrying a failed event triggers all handlers again — if one of three event handlers fails, the retry re-executes the two that already succeeded, causing side effects like duplicate emails or double charges

In Laravel, you've scattered dispatch() calls and ShouldQueue implementations across your codebase. In Symfony, you've configured Messenger transports and retry strategies in YAML, but each handler still needs custom error handling.

What the Industry Calls It

Resilient Messaging — a combination of patterns: failure isolation (per-handler message delivery), automatic retries, error channels, dead letter queues, the outbox pattern for guaranteed delivery, and idempotency for deduplication.

How Ecotone Solves It

With Ecotone, making a handler async is a single attribute. Resilience is built into the messaging layer — not bolted on per handler:

// Make any handler async with one attribute
#[Asynchronous("notifications")]
#[EventHandler]
public function sendWelcomeEmail(UserRegistered $event): void
{
    // If this fails, Ecotone retries automatically
    // If it keeps failing, it goes to the dead letter queue
    // You can replay it after fixing the bug
}

Failure isolation — when multiple handlers subscribe to the same event, Ecotone delivers a separate copy of the message to each handler. If one fails, only that handler is retried — the others are not affected:

#[Asynchronous("notifications")]
#[EventHandler]
public function sendWelcomeEmail(UserRegistered $event): void
{
    // If this fails, only this handler retries
    // The inventory handler below is NOT re-triggered
}

#[Asynchronous("inventory")]
#[EventHandler]
public function reserveInventory(UserRegistered $event): void
{
    // Runs independently — isolated from email handler failures
}

Retries, error channels, and dead letter queues are configured once at the channel level — every handler on that channel gets production resilience automatically. No per-handler boilerplate.

Next Steps

• Asynchronous Handling — Make handlers async with a single attribute
• Message Handling Isolation — Each handler gets its own message copy for safe retries
• Retries — Configure automatic retry strategies
• Error Channel and Dead Letter — Store failed messages for replay
• Outbox Pattern — Guarantee message delivery
• Idempotency (Deduplication) — Prevent double-processing

As You Scale: Ecotone Enterprise adds Command Bus Instant Retries for synchronous commands, Command Bus Error Channel for centralized error routing, and Gateway-Level Deduplication that protects every handler behind a bus automatically.