The logical move toward serverless technologies has also given rise to another paradigm in cloud computing. The following two factors form the basis of event-driven architectures—applications that can subscribe and react to changes within a wider ecosystem:

• Event sourcing is the model for storing the changes of state that a system goes through on an opinionated and real-time basis
• Stream processing is the consumption of these changes for further compute or storage

Many serverless services in AWS are inherently event-driven. Combine this with the fact that they are also highly scalable and resilient and we have the perfect recipe for building distributed systems in the cloud.

In the previous chapter, we learned about the challenges in scaling monolithic services and touched on the challenges in managing a distributed state. This section...