CloudWatch Events EventBridge Event Buses

Amazon EventBridge (formerly CloudWatch Events) provides a fully managed event bus for building scalable, event-driven architectures. In this guide, you’ll learn how EventBridge ingests, routes, and processes events—then see it in action with an e-commerce order processing use case.

Note

EventBridge offers both a default event bus and the ability to create custom buses. You can also subscribe to partner SaaS event sources directly.

Key Features of EventBridge

Feature	Description
Advanced Routing and Patterns	Use content-based filters and transforms to route specific events to the right targets.
Reliable Ingestion and Delivery	Benefit from high throughput, built-in retries, and durable delivery guarantees.
Flexible Event Sources	Connect AWS services, custom applications, and third-party SaaS partners on the same event bus.
Schema Registry and Code Bindings	Define, discover, and enforce JSON schemas—then auto-generate client libraries in multiple languages.

Warning

Be sure to clean up unused rules, buses, and schemas to avoid incurring unexpected charges. See EventBridge pricing.

Real-World Use Case: Order Processing Notifications

Imagine an e-commerce site where, after a successful payment, warehouse staff automatically receive shipping instructions:

A customer places an order via your website, running on an Auto Scaling group of EC2 instances.
The application publishes a PaymentSucceeded event to a custom EventBridge bus.
An EventBridge rule matches on "detail-type": ["PaymentSucceeded"] and forwards the event to a Lambda function.
The Lambda function formats order details and sends an email to the warehouse team.
Warehouse staff receive the notification, pack the items, and dispatch the shipment.

The image illustrates a real-world use case of AWS EventBridge, showing a flow from user interaction through an auto-scaling group, successful payment, event triggering, and rule processing with a Lambda function, leading to email notifications and warehouse updates.

Sample EventBridge Rule (AWS CLI)

# Create the rule
aws events put-rule \
  --name PaymentSucceededRule \
  --event-bus-name custom-order-bus \
  --event-pattern '{
    "detail-type": ["PaymentSucceeded"],
    "source": ["com.myapp.orders"]
  }'

# Attach the Lambda target
aws events put-targets \
  --rule PaymentSucceededRule \
  --event-bus-name custom-order-bus \
  --targets "Id"="1","Arn"="arn:aws:lambda:us-east-1:123456789012:function:NotifyWarehouse"

Next Steps

Define additional event patterns for order cancellations, returns, or promotions.
Explore the EventBridge schema registry to generate strongly typed client code in Java, Python, or TypeScript.
Integrate third-party SaaS partners (e.g., Stripe, Zendesk) for richer cross-system workflows.

Links and References

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