juplo.de Git - demos/kafka/wordcount/blob - src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java

   1 package de.juplo.kafka.wordcount.top10;
   2
   3 import lombok.extern.slf4j.Slf4j;
   4 import org.apache.kafka.streams.*;
   5 import org.apache.kafka.streams.kstream.Materialized;
   6 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
   7 import org.apache.kafka.streams.state.QueryableStoreTypes;
   8 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
   9
  10 import java.util.Properties;
  11
  12
  13 @Slf4j
  14 public class Top10StreamProcessor
  15 {
  16         public static final String STORE_NAME= "top10";
  17
  18         public final KafkaStreams streams;
  19
  20
  21         public Top10StreamProcessor(
  22                         String inputTopic,
  23                         String outputTopic,
  24                         Properties props,
  25                         KeyValueBytesStoreSupplier storeSupplier)
  26         {
  27                 Topology topology = Top10StreamProcessor.buildTopology(
  28                                 inputTopic,
  29                                 outputTopic,
  30                                 storeSupplier);
  31
  32                 streams = new KafkaStreams(topology, props);
  33         }
  34
  35         static Topology buildTopology(
  36                         String inputTopic,
  37                         String outputTopic,
  38                         KeyValueBytesStoreSupplier storeSupplier)
  39         {
  40                 StreamsBuilder builder = new StreamsBuilder();
  41
  42                 builder
  43                                 .<Key, Entry>stream(inputTopic)
  44                                 .map((key, entry) -> new KeyValue<>(User.of(key.getUser()), entry))
  45                                 .groupByKey()
  46                                 .aggregate(
  47                                                 () -> new Ranking(),
  48                                                 (user, entry, ranking) -> ranking.add(entry),
  49                                                 Materialized.as(storeSupplier))
  50                                 .toStream()
  51                                 .to(outputTopic);
  52
  53                 Topology topology = builder.build();
  54                 log.info("\n\n{}", topology.describe());
  55
  56                 return topology;
  57         }
  58
  59         ReadOnlyKeyValueStore<User, Ranking> getStore()
  60         {
  61                 return streams.store(StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore()));
  62         }
  63
  64         public void start()
  65         {
  66                 log.info("Starting Stream-Processor");
  67                 streams.start();
  68         }
  69
  70         public void stop()
  71         {
  72                 log.info("Stopping Stream-Processor");
  73                 streams.close();
  74         }
  75 }