what is an event bus in aws

An event bus in AWS, specifically in Amazon EventBridge, is the routing layer that receives events and sends them to one or more targets based on rules. Think of it as a smart message hub: producers send events in, rules inspect them, and the right AWS services or apps get the events they need.

What it does

• Receives events from AWS services, custom apps, or SaaS partners.

• Uses rules to match events and optionally transform them before delivery.

• Routes events to targets such as Lambda, SQS, SNS, Step Functions, and others.

Main bus types

• Default event bus: created automatically in every AWS account and receives events from AWS services.

• Custom event bus: used for your own applications and workflows.

• Partner event bus: used for events from supported SaaS partners.

Simple example

If an S3 upload happens, EventBridge can put that event on the bus, a rule can match it, and then a Lambda function can run to process the file.

In one line

An AWS event bus is the central router for event-driven systems on EventBridge, helping decouple services so they can react to changes without tight coupling.