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Amazon EventBridge

Cloud Computing · Advanced · 4 min read

What is it?

Amazon EventBridge is AWS's serverless event bus that routes events between AWS services, your apps, and third-party sources based on rules.

Explain like I'm 5

EventBridge is like a smart mailroom: events arrive, and based on rules it sorts each one to exactly the right destinations automatically.

Why was it created?

Wiring many services to react to events with custom code is messy. EventBridge was created as a central, rule-based event router for building event-driven systems.

Where is it used?

  • Event-driven AWS architectures
  • Reacting to AWS service events
  • Integrating SaaS events
  • Routing events to many targets

Why should developers care?

EventBridge is AWS's primary tool for event-driven architectures, so it matters for designing decoupled, reactive cloud systems.

How does it work?

Events flow onto an event bus. You define rules that match event patterns and route matching events to targets like Lambda, SQS, SNS, or other services. It can ingest events from AWS services, your apps, and partner SaaS sources.

Real-world example

A rule matches 'new file uploaded' events and routes them to a Lambda for processing and an SQS queue for archiving — no custom glue code.

Common use cases

  • Decoupled event routing
  • Reacting to AWS events
  • SaaS event integration
  • Fan-out to multiple targets by rule

Advantages

  • Serverless, rule-based routing
  • Connects AWS, custom, and SaaS events
  • Decouples producers/consumers
  • Flexible event filtering

Disadvantages

  • AWS-specific
  • Rule/pattern complexity
  • Harder to trace event flow
  • Not a durable replayable log by default

When should you use it?

When building event-driven systems on AWS that route events to many targets by rule.

When should you avoid it?

For simple one-to-one messaging (SQS) or high-volume replayable streams (Kafka/Kinesis).

Alternatives

Amazon SNS (simpler fan-out)Amazon SQS (queue)Kafka/Kinesis (streaming)

Related terms

Event-Driven ArchitectureAmazon SNSAmazon SQSAWS LambdaAWS

Interview questions

Beginner

  • What is EventBridge?
  • What is an event bus?

Intermediate

  • What is an EventBridge rule?
  • What targets can it route to?

Senior

  • When would you choose EventBridge over SNS?
  • How do you trace events across an event-driven AWS system?

Common misconceptions

  • "EventBridge is just SNS" — it adds rule-based content filtering and routing plus SaaS event integration.
  • "It stores events durably for replay" — it routes events; durable replay needs a stream like Kinesis/Kafka.

Fun facts

  • EventBridge grew out of an earlier AWS service called CloudWatch Events.
  • It can ingest events directly from many third-party SaaS providers.

Timeline

  • 2019 — Amazon EventBridge launches

Learning resources

Quick summary

Amazon EventBridge is a serverless event bus that routes events from AWS, custom apps, and SaaS to targets based on rules, powering event-driven systems.

Cheat sheet

  • Serverless event bus
  • Rule-based event routing
  • AWS + custom + SaaS events
  • Core to event-driven AWS

If you remember only one thing

EventBridge routes events to the right targets by rule, acting as the central nervous system of event-driven AWS apps.