This example implements a simple Hello World REST service using MicroProfile.

With JDK8+

mvn package
java -jar target/helidonbar.jar

curl -X GET http://localhost:8080/greet
{"message":"Hello World!"}

curl -X GET http://localhost:8080/greet/Joe
{"message":"Hello Joe!"}

curl -X PUT -H "Content-Type: application/json" -d '{"greeting" : "Hola"}' http://localhost:8080/greet/greeting

curl -X GET http://localhost:8080/greet/Jose
{"message":"Hola Jose!"}

curl -s -X GET http://localhost:8080/health
{"outcome":"UP",...
. . .

# Prometheus Format
curl -s -X GET http://localhost:8080/metrics
# TYPE base:gc_g1_young_generation_count gauge
. . .

# JSON Format
curl -H 'Accept: application/json' -X GET http://localhost:8080/metrics
{"base":...
. . .

docker build -t helidonbar .

docker run --rm -p 8080:8080 helidonbar:latest

Exercise the application as described above

kubectl cluster-info                         # Verify which cluster
kubectl get pods                             # Verify connectivity to cluster
kubectl create -f app.yaml               # Deploy application
kubectl get service helidonbar  # Verify deployed service

• JAX-RS
  • REST APIs
  • Exception handling
  • Response with Link (Create)
• Config
  • Microprofile configuration options (System, Environment, microprofile-config)
  • System override
    • java -Dapp.welcome="" -jar target\app.jar
  • Environment override
    • Export APP_WELCOME=Welcome {0}
    • java -jar target\app.jar
  • Options
    • @Config / @ConfigProperty
• Health Check
  • In-built outcomes (state & outcome is deprecated in 2.0) /health
    • deadlock detection
    • available disk space
    • available heap memory
  • Custom
    • @Liveness
      • Available in /health/live
    • Readiness
      • @Readiness
      • Available in /health/ready
• Metrics (/metrics) [text and json format]
  • 3 scopes of metrics
    • base (/metrics/base)
    • vendor (/metrics/vendor)
    • application (/metrics/application)
      • types
        • @Counted (Register a Counter metrics)
        • @Timed (Register a Timer metrics)
        • @Metered (Register a Meter metrics)
        • Histogram or Gauge
      • metrics can be configured at the class, method or field
      • Metrics can also be re-used across different methods (reusable = true)
• Fault tolerance
  • Timeout (@Timeout)
  • Retry (@Retry)
  • Fallback (@Fallback)
    • FallbackHandler
    • fallbackMethod
  • Circuit Breaker
    • states (closed / open / half-open)
  • Bulkhead
    • Thread pool isolation (@Bulkhead + @Asynchronous)
      • Max con-current connection + waiting queue size
    • Semaphore isolation (@Bulkhead)
      • con-current number of connection only
• Open API
  • Open api through annotation
  • Static openapi file under META-INF (META-INF/openapi.yaml or openapi.json or openapi.yml)
  • Generate through code (Implement OASModelReader and change configuration 'mp.openapi.model.reader')
• Rest Client
  • Type based rest client
  • Rest client with annotation
• JWT Authentication
  • TODO
• Open tracing
  • @Tracing
  • Zipkin / Jaeger
• General
  • Start up / Shutdown listener

https://download.eclipse.org/microprofile/
https://github.com/eclipse/microprofile
https://countrycode.org/
https://www.sport-histoire.fr/en/Geography/ISO_codes_countries.php
https://dennis-xlc.gitbooks.io/restful-java-with-jax-rs-2-0-en/content/en/index.html