PATTERN Cited by 1 source
SNS cross-region fan-out¶
Pattern¶
Configure an Amazon SNS topic in each source region with cross-region subscriptions targeting SQS queues in multiple destination regions. Every published event is simultaneously delivered to all subscribed queues regardless of their region, enabling active-active event processing architectures.
Mechanism¶
Source Region (eu-west-1)
SNS Topic
├──→ SQS in us-east-1 (primary infrastructure)
└──→ SQS in us-west-2 (secondary infrastructure)
Each customer/source region maintains its own SNS topic. The subscription configuration is purely declarative — no application code change required to add a new destination region.
Trade-offs¶
| Pro | Con |
|---|---|
| Simple to configure — SNS handles cross-region delivery natively | Cross-region data transfer costs scale with message volume |
| No code change to add new target regions | Message ordering not guaranteed across regions |
| Fan-out is atomic from publisher's perspective | Requires idempotency/dedup at consumers (both receive same event) |
| Works with any number of source regions | SNS subscription limits apply (per-topic cap) |
When to use¶
- Active-active architectures where events must reach multiple processing regions simultaneously.
- Disaster recovery scenarios requiring real-time event replication without database-level DR.
- Multi-region custom resource or webhook processing (the event originates in one region but must be processable in any).
Seen in¶
- sources/2026-07-22-aws-building-multi-region-resiliency-for-cloudformation-custom-resources — customer regions fan out CloudFormation lifecycle events to both infrastructure regions via SNS cross-region subscriptions to SQS (AWS Architecture Blog, 2026-07-22).