API Composition - A Microservices Pattern
Microservices patterns from Chris Richardson's Microservices Patterns book.
Once you apply the Database Per Service pattern, you may face a challenge to "join" data from different databases.
The API Composition pattern addresses this by combining 2 (or more) services by joining their APIs.
In this example, I have implemented the pattern using Project Reactor and WebClient from Spring Webflux.