Event Bus (EventBridge / Event Grid)

Definition

A serverless event bus that connects applications together using data from your own apps, SaaS apps, and cloud services. It routes real-time 'events' to various targets based on complex rules.

Explain Like I'm New

The post office sorting facility. A package (an event) arrives. The post office looks at the zip code (the rule), and decides whether to send it to an email address, a Lambda function, or a database.

Real World Example

AWS EventBridge. An HR SaaS application emits an event: 'New Employee Hired'. EventBridge reads the event, triggers a Lambda function to create the employee's email address, and simultaneously sends an SQS message to the payroll system to start their salary.

Common Use Cases

•Event-driven architectures
•SaaS integration
•Choreography

Interview Questions

basic

What is the primary difference between a Message Queue (SQS) and an Event Bus (EventBridge)?

intermediate

What is a 'Target' in EventBridge?

Flash Cards

Question

Queue vs Event Bus?

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Answer

A Queue is a 1-to-1 pipe designed to hold work until a specific worker is ready. An Event Bus is a 1-to-Many router. It broadcasts 'Something Happened!' and routes that event to multiple different services simultaneously based on rules.

Question

What is a Target?

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Answer

A target is the final destination service that the Event Bus sends the event to for processing (e.g., an AWS Lambda function, an SNS topic, or a Step Functions workflow).