Building Event-Driven Systems on AWS: EventBridge vs. SQS vs. SNS
Learn when to use Amazon EventBridge, SQS, and SNS in event-driven architectures. Compare latency, message filtering, routing patterns, and real-world microservices integration
Introduction
Event-driven architecture (EDA) decouples applications so components scale and fail independently. However, a common challenge when building on AWS is selecting the right messaging service: Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), or Amazon EventBridge.
While all three enable asynchronous communication, each is tailored for distinct architectural patterns.
Service Breakdown
1. Amazon SQS (Point-to-Point Queueing)
Amazon SQS is a fully managed message queuing service designed for decoupling producer and consumer workloads.
- Pattern: Point-to-Point (Queue).
- Key Feature: Pull-based model where consumers poll messages at their own processing speed.
- Best Used For:
- Buffering heavy incoming traffic (e.g., flash sales, bulk event ingests).
- Ensuring message delivery with Dead Letter Queues (DLQ) and exponential backoff retries.
2. Amazon SNS (High-Throughput Fan-Out)
Amazon SNS is a lightweight publish/subscribe (Pub/Sub) messaging service that delivers messages instantaneously to multiple endpoints.
- Pattern: Pub/Sub (Fan-Out).
- Key Feature: Push-based model with ultra-low latency delivery.
- Best Used For:
- Delivering a single message simultaneously to multiple downstream queues or HTTP webhooks.
- Triggering instant notifications via Email, SMS, or Mobile Push notifications.
3. Amazon EventBridge (Event Bus & Router)
Amazon EventBridge is a serverless event bus that connects application data from your own microservices, SaaS applications, and AWS services.
- Pattern: Event Bus (Content-Based Routing).
- Key Feature: Advanced schema matching, pattern filtering, and native integration with 200+ AWS services.
- Best Used For:
- Complex cross-microservice workflows requiring detailed event rules.
- Ingesting third-party SaaS events (e.g., Stripe, Shopify, GitHub) directly into AWS Lambda.
Feature Comparison Matrix
| Feature | Amazon SQS | Amazon SNS | Amazon EventBridge |
|---|---|---|---|
| Messaging Model | Pull (Polling) | Push (Pub/Sub) | Push (Event Bus) |
| Max Payload Size | 1 MB | 256 KB | 1 MB |
| Message Filtering | None (Raw messages) | Basic (Attributes) | Advanced (JSON Content Matching) |
| SaaS Integrations | No | No | Yes (Native) |
| Ordering | FIFO Queues supported | FIFO Topics supported | Target-dependent |
Architectural Patterns & Best Practices
Pattern 1: Fan-Out to Multiple Consumers (SNS + SQS)
When a single event must trigger distinct actions across independent services (e.g., an
OrderPlaced event requiring Payment Processing, Inventory Adjustment, and Email Confirmation):Enjoyed reading this content? Let the author know!
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