Hooksbase

Glossary · Architecture

Fan-out

Delivering one event to multiple consumers in parallel.

Architecture

What is fan-out?

Fan-out is delivering one event to multiple consumers in parallel. A payment_failed webhook might trigger a recovery agent, update the billing database, post to a Slack channel, and update an analytics dashboard — all from the same source event.

In webhook systems, fan-out happens at one of two layers:

  • At the event layer — some systems create multiple deliveries from one incoming event, one per consumer.
  • At a downstream broker — the event layer delivers to a single broker (SNS, EventBridge, Kafka), which fans out to internal consumers.

Hooksbase v1 does routing, not event-layer fan-out: priority-ordered rules select one destination for each event, with a default destination as the fallback. To fan out one Hooksbase delivery to multiple consumers, route it to a downstream broker or to an HTTP destination that owns that fan-out.

When to fan out at the event layer vs at the broker

Fan-out at the event layer is the right answer when your event infrastructure supports it and:

  • The destinations are heterogeneous (HTTP endpoint, SQS queue, S3 bucket)
  • The fan-out is cross-system (your customer's endpoint, your internal queue, an audit log)
  • You want one queryable delivery history per destination

Fan-out at a broker is the right answer when:

  • The destinations are all internal AWS services (SNS subscribers, EventBridge targets)
  • You need per-consumer offset tracking (Kafka consumer groups)
  • The throughput exceeds what HTTP delivery can comfortably handle

For most Hooksbase agent systems today, choose a single destination with routing rules, or hand off to a broker when multiple consumers must process the same event.

For the design framework: Routing, transforms, and replay for AI agents.

Frequently asked questions

Should fan-out happen at the event layer or at a downstream broker?

At the event layer when the destinations are heterogeneous — an HTTP endpoint, a queue, a bucket — when the fan-out crosses systems, or when you want one queryable delivery history per destination. At a broker when the consumers are all internal AWS services, when you need per-consumer offset tracking, or when throughput exceeds what HTTP delivery handles comfortably.

Does Hooksbase fan one event out to multiple destinations?

Not in v1. Hooksbase does routing: priority-ordered rules select a single destination for each event, with a default destination as the fallback. To reach several independent consumers, route to a downstream broker such as EventBridge, SQS or SNS, or to an HTTP service that owns the fan-out.

What is Hooksbase?

Hooksbase is event infrastructure for AI agents. It ingests events over four channels — HTTP, email, HTML form, and scheduled cron — verifies them, routes them by rule, runs versioned Automations in the event path, and delivers them to HTTP and cloud destinations (AWS SQS, AWS EventBridge, GCP Pub/Sub, and S3-compatible storage) with retries, strict ordering, Standard Webhooks-compatible signing, deterministic replay, and a dead-letter path. It is a hosted service, runs on Cloudflare Workers, is operated at hooksbase.com, and is not affiliated with — and shares no code or ownership with — other similarly named webhook, hook, or tunnelling tools.

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