1. Distributed tracing provides a micro-view of what happened with a request from end to end, whereas metrics expose scalar numerical values from a single component.
2. Distributed tracing systems usually provide features such as the root cause and critical path analysis, contextualized logging, distributed context propagation, and service dependency diagrams.
3. Automatically traced are JAX-RS server endpoints and MicroProfile Rest clients. Some vendors can also automatically trace JAX-RS clients.
4. These tags are added for every REST request http.method, http.status_code, http.url, component, span.kind and error if an exception is thrown.
5. Explicit instrumentation can be added by using @Traced annotation or injecting the tracer and creating spans manually.
6. There are three scopes: base for server metrics that apply to all runtimes, vendor for metrics that are server-specific,...