In this chapter, we learned about the observability of servers and applications.
Metrics, or telemetry, can help to pinpoint the performance characteristics of a server or an application. MicroProfile offers, via the Metrics specification, a way to export Metrics in standardized ways. Application writers can use MicroProfile Metrics to expose their data to monitoring clients decoratively via annotations or via calls to the Metrics API.
The chapter further explained how OpenTracing integration in MicroProfile provides an end-to-end view for each individual transaction going through the system. We went through the configuration properties, showcasing tracing for JAX-RS, and finally investigating data in the Jaeger system.
In the next chapter, we will learn how to document (REST) APIs via OpenAPI and call those APIs via the type-safe REST client.
