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AMQP event bridge

AMQP Event Bridge ​

The @purista/amqpbridge package connects PURISTA to AMQP brokers such as RabbitMQ.

Delivery semantics ​

  • durability: supported (durable queues/exchanges)
  • retries: supported (broker + consumer policies)
  • dead-lettering: supported by broker configuration
  • subscription consumer failure handling: supported with bridge-managed bounded retries and dead-letter queue routing
  • typical delivery mode: at-least-once when durable queues use manual ack (duplicates must be handled)

Durable command consumers now default to:

  • autoacknowledge: false
  • autoDelete: false
  • configurable prefetch
  • optional dead-letter exchange / routing-key arguments

This makes the safe path the default for durable command workloads instead of requiring every service to override queue settings manually.

For command invocation, PURISTA keeps a pending invocation timeout registry and additionally sets AMQP message expiration from the invocation timeout. This combines caller-side timeout determinism with broker-side stale-message expiry. Command handlers are single-shot request/response: failures are returned as CommandErrorResponse (UnhandledError) and the original delivery is settled once, not retried through subscription-style redelivery.

Durable subscriptions can now also declare consumerFailureHandling:

  • maxAttempts is honored by the bridge through bounded republish
  • deadLetterTarget is honored as the terminal queue name
  • retryDelayMs is honored for durable subscriptions through bridge-managed broker retry queues (TTL + dead-letter back to source queue)
  • mode: 'strict' keeps startup honest by rejecting unsupported semantics instead of degrading silently
  • explicit handler outcomes:
    • drop: ack and discard the current delivery with warning metadata
    • stop-consumer: cancel and pause the affected consumer tag until explicit resume

Stream support ​

PURISTA stream runtime (openStream) is currently not implemented for AMQP bridge.

Example ​

typescript
import { AmqpBridge } from '@purista/amqpbridge'

const eventBridge = new AmqpBridge({
  url: 'amqp://my-amqp-host.example.com',
})

await eventBridge.start()

Reliability recommendations ​

  • configure durable queues for long-lived subscriptions
  • configure dead-letter queues for poison messages
  • use confirm-channel backed retry/DLQ handoff so the original delivery is not acknowledged before the retry/DLQ write is accepted
  • monitor paused subscription consumers and resume them deliberately after remediation
  • use queue bridges instead of subscriptions when you need long backoff windows or operator-driven replay
  • keep manual ack enabled for durable command consumers
  • make command/subscription handlers idempotent
  • align exchange/queue naming and routing settings across all instances