Chapter 6: A Best Friend for the Frontend

In Chapter 4, Trusting Facts and Eventual Consistency, we covered the event sourcing pattern and learned how it creates an outbound bulkhead that protects upstream services from downstream outages. In Chapter 5, Turning the Cloud into the Database, we covered the command query responsibility segregation (CQRS) pattern and learned how it creates an inbound bulkhead that protects downstream services from upstream outages. Together, these bulkheads fortify the boundaries of autonomous services and give teams the confidence to forge ahead with changes, knowing that these boundaries will help control the blast radius when things go wrong.

Now we'll turn our attention to the boundary service patterns that work at the periphery of the system. These autonomous services are responsible for catering to the kinds of changes driven by external actors, such as end users and external systems. In this chapter, we will focus on supporting end users...