Amazon EventBridge

Amazon EventBridge is a serverless event bus that connects applications using events. It enables event-driven architectures by routing events between AWS services, SaaS applications, and your own applications.

Key Concepts

• Events: JSON objects describing state changes
• Event Bus: A router that receives events and applies rules
• Rules: Define which events to capture and where to send them
• Targets: Destinations for events (Lambda, SQS, SNS, Step Functions, etc.)

Event Sources

• AWS Services: Over 90 AWS services emit events (S3, EC2, CodePipeline, etc.)
• SaaS Partners: Zendesk, Datadog, Auth0, and others
• Custom Applications: Send your own events via the API

Example Event

{
  "source": "myapp.orders",
  "detail-type": "Order Placed",
  "detail": {
    "orderId": "12345",
    "customerId": "67890",
    "amount": 99.99
  }
}

Common Patterns

Scheduled Events

Run Lambda functions on a schedule (like cron):

rate(5 minutes)
cron(0 12 * * ? *)

Cross-Account Events

Send events between AWS accounts for decoupled architectures.

Event Archive and Replay

Store events and replay them for debugging or reprocessing.

What We Like

• Decoupling: Producers and consumers don't need to know about each other
• Native integrations: First-class support for AWS services
• Schema registry: Automatic schema discovery and versioning
• Reliability: Built-in retry logic and dead-letter queues

What We Don't Like

• Debugging complexity: Tracing events through multiple services can be challenging
• Eventual consistency: Not suitable for synchronous request/response patterns
• Rule limits: Complex routing logic can hit rule limits

EventBridge vs SNS vs SQS

Service	Pattern	Use When
EventBridge	Event routing	Content-based routing, multiple consumers
SNS	Pub/Sub	Simple fan-out to multiple subscribers
SQS	Queue	Decoupling with guaranteed delivery