How to choose between EventBridge and SQS in Event Driven Architecture

EventBridge, SQS are two event based orchestration services offered by AWS. They are solving similar scenarios:providers deliver events to consumers but provide very different in terms of functionalities.

In this article, I will go through some event driven scenarios to discuss when to use each of these services and compare the pros and cons among them. I won’t explain the basic technologies of them which can be found easily from AWS docs or other tutorials, I expect you have some general knowledge about them. If you don’t, please have a read through https://aws.amazon.com/blogs/compute/choosing-between-messaging-services-for-serverless-applications/.

What is Event

The core function those services want to support is Event but what is event, how is it different than others? When we look at building an application in the backend, usually we deploy an API and some handlers to take requests from frontend and save/query from database. It works fine for a simple system but is not scalable when it comes to micro-service design. Multiple services need to communicate between each other, such as API call, data sync, data populate etc. e.g. one service takes an action and multiple other services need to response to this action. Traditionally this service has to call other service via API one by one which is very limited in terms of scale, design change, performance since all services are coupled together.