When we design our architecture and build our services it can be useful to know the different types of communication patterns. Although pretty simple, I think it’s important to know the difference between sync and async.

Sync

• Normally seen as the “request/response” pattern. Example would be taking a phone call, you need both parties there.
• An example of this could be a command, many API calls want something to happen.
• Fails fast, simple and low latency
• What happens when many requests come in? Need to scale the service, could you use Async pattern instead? Something to consider.

Async

• With EDA a producer can fire an event and forget it and allow downstream consumers to process it (if they want…)
• With messages, a message could be added to queue and downstream services control the speed of injestion and process async.
• Async provides a loose coupling between services/systems.
• Receiver can control the rate of consumption of events/messages
• Example of this would be Amazon SQS.

Extra resources

• AWS: Re:invent 2022 - Building next-gen applications with event-driven architectures - Video on building EDA applications and speaker talks through communication patterns.