Introduction

The events we have worked with so far have been synchronously handled. The domain events were used to move the side effects of domain-model changes into external handlers.

External handlers were called after the change was made successfully and within the same process. We used events to record each change made to our domain aggregates. When we want to use an aggregate, we read all of the events in sequence to rebuild the current state of the aggregate. With both kinds of events, our system is immediately or strongly consistent because events are always created or read within a single process.

Chapter overview

In this chapter, we are going to cover the following main topics, as illustrated in the figure below: