/jeopardized

This project is a simple demo showcasing everything that might be needed for our first NVS-Test this year.

Primary LanguageJava

Jeopardized

Table of Contents

General

This project is a simple demo showcasing everything that might be needed for our first NVS-Test this year.

What it does

It gets data from the popular American gameshow Jeopardy via a public API and stores them in a db

Model

The Model is quite simple:

Clues (or rather Questions) are placed in a certain Category.

CLD

Tips and Tricks

ReSTClient

General

Implementing a RestClient:

import javax.ws.rs.PathParam;
import javax.ws.rs.QueryParam;@RegisterRestClient
public interface SomeService {

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    @Path("somePath/{someParam}")
    Object someMethod(@PathParam("someParam") int someParam,@QueryParam("queryParam") int anotherParam);
}

With config file:

some.path.to.SomeService/mp-rest/url=http://www.somepage.io/api

Results in this GET Request:

Paging

Paging is basically splitting requested resources so that huge datasets don’t get returned as a whole and are split in little chunks

Paging in the ReST-Client is basically having some @QueryParam’s

Implementing Paging on the server is also relatively easy

@Path("somePath")
@Produces(MediaType.APPLICATION_JSON)
public class SomeEndpoint {
    @Inject
    SomeDao someDao;

    @GET
    public Response getSomeEntity(@QueryParam("offset")@DefaultValue("0")int offset,@QueryParam("limit")@DefaultValue("20")int limit){
        return Response.ok(someDao.getAll(offset,limit)).build();
    }
}

In combination with:

@ApplicationScoped
public class SomeDao {

    @PersistenceContext
    EntityManager em;

    public List<SomeEntity> getAll(int offset,int limit) {
        TypedQuery<SomeEntity> query = em.createNamedQuery("SomeEntity.findAll",SomeEntity.class);
        query.setFirstResult(offset);
        query.setMaxResults(limit);
        return query.getResultList();
    }

}

This makes Paging with default values 0 for the offset and 20 for the count of returned objects

JPA

Use for relations:

@OneToMany(mappedBy = "name_of_field_of_this_class_in_other_class",cascade = {CascadeType.REFRESH, CascadeType.MERGE})
//and
@ManyToOne(cascade = {CascadeType.REFRESH, CascadeType.MERGE})

Jax-RS

@DefaultValue("someValue")

might be useful for some query params

Metrics, Fault Tolerance

if needed, here are some metrics/fault tolerance annotations

import org.eclipse.microprofile.faulttolerance.*;
import org.eclipse.microprofile.metrics.*;

@Counted(name = "average_value_count") //count calls of method
@Bulkhead(value = 2,waitingTaskQueue = 8) //this method can be called 2 times simultaneously, and 8 calls can be put in a queue
@Timed(name = "clue_of_category",unit = MetricUnits.MILLISECONDS) //measure how long this method call takes
@Fallback(fallbackMethod = "someMethod") // if method throws exception ,try fallBackMethod
@CircuitBreaker(failureRatio = 0.75,requestVolumeThreshold = 4,delay = 1,delayUnit = ChronoUnit.SECONDS) //if 75% of 4 consecutive calls fail, wait 1 second and let them retry
@Retry(maxRetries = "2") //if method fails, let it retry 2 times
@Timeout(500) // if method call takes longer than 500 ms, abort

Deployment

For Deployment, my script usually contains 3 steps:

  1. Build the project database

  2. Build an image for this quarkus project

  3. Run a container for our built image

docker-compose.yml:

version: "3.5"
services:
  database:
    container_name: somedatasource
    image: postgres:latest
    environment:
      POSTGRES_PASSWORD: passme
      POSTGRES_USER: someProjectName
      POSTGRES_DB: someProjectName
      PG_DATA: /var/lib/postgresql/data/pgdata
    volumes:
      - someVolumeName:/var/lib/postgresql/data
    ports:
      - 5432:5432
    networks:
      - someNetwork
volumes:
  someVolumeName:
    name: somedatasource_data

networks:
  someNetwork
    name: SomeProjectNet
    driver: bridge

buildSomeProject.sh

mvn package
docker build -f src/main/docker/Dockerfile.jvm -t someProjectNameImage .

and running the container

docker run -i --rm -p 8080:8080 --net SomeProjectNet --link  somedatasource --name containerName someProjectNameImage