Using Apache Kafka Streams

./mvnw clean package -f producer/pom.xml
./mvnw clean package -f aggregator/pom.xml

version: '3.5'

services:
  zookeeper:
    image: strimzi/kafka:0.19.0-kafka-2.5.0
    command: [
      "sh", "-c",
      "bin/zookeeper-server-start.sh config/zookeeper.properties"
    ]
    ports:
      - "2181:2181"
    environment:
      LOG_DIR: /tmp/logs
    networks:
      - kafkastreams-network
  kafka:
    image: strimzi/kafka:0.19.0-kafka-2.5.0
    command: [
      "sh", "-c",
      "bin/kafka-server-start.sh config/server.properties --override listeners=$${KAFKA_LISTENERS} --override advertised.listeners=$${KAFKA_ADVERTISED_LISTENERS} --override zookeeper.connect=$${KAFKA_ZOOKEEPER_CONNECT} --override num.partitions=$${KAFKA_NUM_PARTITIONS}"
    ]
    depends_on:
      - zookeeper
    ports:
      - "9092:9092"
    environment:
      LOG_DIR: "/tmp/logs"
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://kafka:9092
      KAFKA_LISTENERS: PLAINTEXT://0.0.0.0:9092
      KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
      KAFKA_NUM_PARTITIONS: 3
    networks:
      - kafkastreams-network

  producer:
    image: quarkus-quickstarts/kafka-streams-producer:1.0
    build:
      context: producer
      dockerfile: src/main/docker/Dockerfile.${QUARKUS_MODE:-jvm}
    environment:
      KAFKA_BOOTSTRAP_SERVERS: kafka:9092
    networks:
      - kafkastreams-network

  aggregator:
    image: quarkus-quickstarts/kafka-streams-aggregator:1.0
    build:
      context: aggregator
      dockerfile: src/main/docker/Dockerfile.${QUARKUS_MODE:-jvm}
    environment:
      QUARKUS_KAFKA_STREAMS_BOOTSTRAP_SERVERS: kafka:9092
    networks:
      - kafkastreams-network

networks:
  kafkastreams-network:
    name: ks

docker run --tty --rm -i --network ks debezium/tooling:1.1

kafkacat -b kafka:9092 -C -o beginning -q -t temperatures-aggregated

{"avg":34.7,"count":4,"max":49.4,"min":16.8,"stationId":9,"stationName":"Marrakesh","sum":138.8}
{"avg":15.7,"count":1,"max":15.7,"min":15.7,"stationId":2,"stationName":"Snowdonia","sum":15.7}
{"avg":12.8,"count":7,"max":25.5,"min":-13.8,"stationId":7,"stationName":"Porthsmouth","sum":89.7}
...

package org.acme.kafka.streams.aggregator.streams;

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;

import org.acme.kafka.streams.aggregator.model.Aggregation;
import org.acme.kafka.streams.aggregator.model.WeatherStationData;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.errors.InvalidStateStoreException;
import org.apache.kafka.streams.state.QueryableStoreTypes;
import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;

@ApplicationScoped
public class InteractiveQueries {

    @Inject
    KafkaStreams streams;

    public GetWeatherStationDataResult getWeatherStationData(int id) {
        Aggregation result = getWeatherStationStore().get(id);

        if (result != null) {
            return GetWeatherStationDataResult.found(WeatherStationData.from(result)); (1)
        }
        else {
            return GetWeatherStationDataResult.notFound();                             (2)
        }
    }

    private ReadOnlyKeyValueStore<Integer, Aggregation> getWeatherStationStore() {
        while (true) {
            try {
                return streams.store(TopologyProducer.WEATHER_STATIONS_STORE, QueryableStoreTypes.keyValueStore());
            } catch (InvalidStateStoreException e) {
                // ignore, store not ready yet
            }
        }
    }
}

package org.acme.kafka.streams.aggregator.streams;

import java.util.Optional;
import java.util.OptionalInt;

import org.acme.kafka.streams.aggregator.model.WeatherStationData;

public class GetWeatherStationDataResult {

    private static GetWeatherStationDataResult NOT_FOUND =
            new GetWeatherStationDataResult(null);

    private final WeatherStationData result;

    private GetWeatherStationDataResult(WeatherStationData result) {
        this.result = result;
    }

    public static GetWeatherStationDataResult found(WeatherStationData data) {
        return new GetWeatherStationDataResult(data);
    }

    public static GetWeatherStationDataResult notFound() {
        return NOT_FOUND;
    }

    public Optional<WeatherStationData> getResult() {
        return Optional.ofNullable(result);
    }
}

package org.acme.kafka.streams.aggregator.model;

import io.quarkus.runtime.annotations.RegisterForReflection;

@RegisterForReflection
public class WeatherStationData {

    public int stationId;
    public String stationName;
    public double min = Double.MAX_VALUE;
    public double max = Double.MIN_VALUE;
    public int count;
    public double avg;

    private WeatherStationData(int stationId, String stationName, double min, double max,
            int count, double avg) {
        this.stationId = stationId;
        this.stationName = stationName;
        this.min = min;
        this.max = max;
        this.count = count;
        this.avg = avg;
    }

    public static WeatherStationData from(Aggregation aggregation) {
        return new WeatherStationData(
                aggregation.stationId,
                aggregation.stationName,
                aggregation.min,
                aggregation.max,
                aggregation.count,
                aggregation.avg);
    }
}

package org.acme.kafka.streams.aggregator.rest;

import java.net.URI;
import java.net.URISyntaxException;
import java.util.List;

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;

import org.acme.kafka.streams.aggregator.streams.GetWeatherStationDataResult;
import org.acme.kafka.streams.aggregator.streams.KafkaStreamsPipeline;

@ApplicationScoped
@Path("/weather-stations")
public class WeatherStationEndpoint {

    @Inject
    InteractiveQueries interactiveQueries;

    @GET
    @Path("/data/{id}")
    public Response getWeatherStationData(int id) {
        GetWeatherStationDataResult result = interactiveQueries.getWeatherStationData(id);

        if (result.getResult().isPresent()) {  (1)
            return Response.ok(result.getResult().get()).build();
        }
        else {
            return Response.status(Status.NOT_FOUND.getStatusCode(),
                    "No data found for weather station " + id).build();
        }
    }
}

./mvnw clean package -f aggregator/pom.xml
docker-compose stop aggregator
docker-compose up --build -d

http aggregator:8080/weather-stations/data/1

HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 85
Content-Type: application/json
Date: Tue, 18 Jun 2019 19:29:16 GMT

{
    "avg": 12.9,
    "count": 146,
    "max": 41.0,
    "min": -25.6,
    "stationId": 1,
    "stationName": "Hamburg"
}

public GetWeatherStationDataResult getWeatherStationData(int id) {
    StreamsMetadata metadata = streams.metadataForKey(                  (1)
            TopologyProducer.WEATHER_STATIONS_STORE,
            id,
            Serdes.Integer().serializer()
    );

    if (metadata == null || metadata == StreamsMetadata.NOT_AVAILABLE) {
        LOG.warn("Found no metadata for key {}", id);
        return GetWeatherStationDataResult.notFound();
    }
    else if (metadata.host().equals(host)) {                            (2)
        LOG.info("Found data for key {} locally", id);
        Aggregation result = getWeatherStationStore().get(id);

        if (result != null) {
            return GetWeatherStationDataResult.found(WeatherStationData.from(result));
        }
        else {
            return GetWeatherStationDataResult.notFound();
        }
    }
    else {                                                              (3)
        LOG.info(
            "Found data for key {} on remote host {}:{}",
            id,
            metadata.host(),
            metadata.port()
        );
        return GetWeatherStationDataResult.foundRemotely(metadata.host(), metadata.port());
    }
}

public List<PipelineMetadata> getMetaData() {                           (4)
    return streams.allMetadataForStore(TopologyProducer.WEATHER_STATIONS_STORE)
            .stream()
            .map(m -> new PipelineMetadata(
                    m.hostInfo().host() + ":" + m.hostInfo().port(),
                    m.topicPartitions()
                        .stream()
                        .map(TopicPartition::toString)
                        .collect(Collectors.toSet()))
            )
            .collect(Collectors.toList());
}

package org.acme.kafka.streams.aggregator.streams;

import java.util.Optional;
import java.util.OptionalInt;

import org.acme.kafka.streams.aggregator.model.WeatherStationData;

public class GetWeatherStationDataResult {

    private static GetWeatherStationDataResult NOT_FOUND =
            new GetWeatherStationDataResult(null, null, null);

    private final WeatherStationData result;
    private final String host;
    private final Integer port;

    private GetWeatherStationDataResult(WeatherStationData result, String host,
            Integer port) {
        this.result = result;
        this.host = host;
        this.port = port;
    }

    public static GetWeatherStationDataResult found(WeatherStationData data) {
        return new GetWeatherStationDataResult(data, null, null);
    }

    public static GetWeatherStationDataResult foundRemotely(String host, int port) {
        return new GetWeatherStationDataResult(null, host, port);
    }

    public static GetWeatherStationDataResult notFound() {
        return NOT_FOUND;
    }

    public Optional<WeatherStationData> getResult() {
        return Optional.ofNullable(result);
    }

    public Optional<String> getHost() {
        return Optional.ofNullable(host);
    }

    public OptionalInt getPort() {
        return port != null ? OptionalInt.of(port) : OptionalInt.empty();
    }
}

package org.acme.kafka.streams.aggregator.streams;

import java.util.Set;

public class PipelineMetadata {

    public String host;
    public Set<String> partitions;

    public PipelineMetadata(String host, Set<String> partitions) {
        this.host = host;
        this.partitions = partitions;
    }
}

package org.acme.kafka.streams.aggregator.rest;

import java.net.URI;
import java.net.URISyntaxException;
import java.util.List;

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import javax.ws.rs.Consumes;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;

import org.acme.kafka.streams.aggregator.streams.GetWeatherStationDataResult;
import org.acme.kafka.streams.aggregator.streams.KafkaStreamsPipeline;
import org.acme.kafka.streams.aggregator.streams.PipelineMetadata;

@ApplicationScoped
@Path("/weather-stations")
public class WeatherStationEndpoint {

    @Inject
    InteractiveQueries interactiveQueries;

    @GET
    @Path("/data/{id}")
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    public Response getWeatherStationData(int id) {
        GetWeatherStationDataResult result = interactiveQueries.getWeatherStationData(id);

        if (result.getResult().isPresent()) {                     (1)
            return Response.ok(result.getResult().get()).build();
        }
        else if (result.getHost().isPresent()) {                  (2)
            URI otherUri = getOtherUri(result.getHost().get(), result.getPort().getAsInt(),
                    id);
            return Response.seeOther(otherUri).build();
        }
        else {                                                    (3)
            return Response.status(Status.NOT_FOUND.getStatusCode(),
                    "No data found for weather station " + id).build();
        }
    }

    @GET
    @Path("/meta-data")
    @Produces(MediaType.APPLICATION_JSON)
    public List<PipelineMetadata> getMetaData() {                 (4)
        return interactiveQueries.getMetaData();
    }

    private URI getOtherUri(String host, int port, int id) {
        try {
            return new URI("http://" + host + ":" + port + "/weather-stations/data/" + id);
        }
        catch (URISyntaxException e) {
            throw new RuntimeException(e);
        }
    }
}

./mvnw clean package -f aggregator/pom.xml
docker-compose stop aggregator
docker-compose up --build -d --scale aggregator=3

http aggregator:8080/weather-stations/meta-data

HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 202
Content-Type: application/json
Date: Tue, 18 Jun 2019 20:00:23 GMT

[
    {
        "host": "2af13fe516a9:8080",
        "partitions": [
            "temperature-values-2"
        ]
    },
    {
        "host": "32cc8309611b:8080",
        "partitions": [
            "temperature-values-1"
        ]
    },
    {
        "host": "1eb39af8d587:8080",
        "partitions": [
            "temperature-values-0"
        ]
    }
]

http 2af13fe516a9:8080/weather-stations/data/1

HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 74
Content-Type: application/json
Date: Tue, 11 Jun 2019 19:16:31 GMT

{
  "avg": 11.9,
  "count": 259,
  "max": 50.0,
  "min": -30.1,
  "stationId": 1,
  "stationName": "Hamburg"
}

HTTP/1.1 303 See Other
Connection: keep-alive
Content-Length: 0
Date: Tue, 18 Jun 2019 20:01:03 GMT
Location: http://1eb39af8d587:8080/weather-stations/data/1

http --follow 2af13fe516a9:8080/weather-stations/data/1

./mvnw clean package -f producer/pom.xml -Dnative -Dnative-image.container-runtime=docker
./mvnw clean package -f aggregator/pom.xml -Dnative -Dnative-image.container-runtime=docker

export QUARKUS_MODE=native

CMD ["./application", "-Dquarkus.http.host=0.0.0.0", "-Xmx32m"]

curl -i http://aggregator:8080/q/health

HTTP/1.1 503 Service Unavailable
content-type: application/json; charset=UTF-8
content-length: 454

{
    "status": "DOWN",
    "checks": [
        {
            "name": "Kafka Streams state health check",  (1)
            "status": "DOWN",
            "data": {
                "state": "CREATED"
            }
        },
        {
            "name": "Kafka Streams topics health check",  (2)
            "status": "DOWN",
            "data": {
                "available_topics": "weather-stations,temperature-values",
                "missing_topics": "hygrometry-values"
            }
        }
    ]
}