In a distributed system your services usually communicate via HTTP and expose REST APIs. External clients or other services in your system consume these endpoints on a regular basis to e.g. fetch data from a different part of the domain. If you are using Java EE you can utilize the JAX-RS WebTarget and Client for

Tracing method calls in a monolith to identify slow parts is simple. Everything is happening in one application (context) and you can easily add metrics to gather information about e.g. the elapsed time for fetching data from the database. Once you have a microservice environment with service-to-service communication, tracing needs more effort. If a business

Exposing REST endpoints usually requires documentation for your clients. This documentation usually includes the following: accepted media types, HTTP method, path variables, query parameters, and the request and response schema. With the OpenAPI v3 specification we have a standard way to document APIs. You can generate this kind of API documentation from your JAX-RS classes

Once your application is deployed to production you want to ensure it’s up– and running. To determine the health and status of your application you can use monitoring based on different metrics, but this requires further knowledge and takes time. Usually, you just want a quick answer to the question: Is my application up? The

Ensuring a stable operation of your application in production requires monitoring. Without monitoring, you have no insights about the internal state and health of your system and have to work with a black-box. MicroProfile Metrics gives you the ability to not only monitor pre-defined metrics like JVM statistics but also create custom metrics to monitor

Injecting configuration properties like JDBC URLs, passwords, usernames, or hostnames from external sources is a common requirement for every application. Inspired by the twelve-factor app principles you should store configuration in the environment (e.g. OS environment variables or config maps in Kubernetes). These external configuration properties can then be replaced for your different stages (dev/prod/test) with