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 final KafkaStreams streams;
  17
  18
  19         public Top10StreamProcessor(
  20                         String inputTopic,
  21                         String outputTopic,
  22                         Properties props,
  23                         KeyValueBytesStoreSupplier storeSupplier)
  24         {
  25                 Topology topology = Top10StreamProcessor.buildTopology(
  26                                 inputTopic,
  27                                 outputTopic,
  28                                 storeSupplier);
  29
  30                 streams = new KafkaStreams(topology, props);
  31         }
  32
  33         static Topology buildTopology(
  34                         String inputTopic,
  35                         String outputTopic,
  36                         KeyValueBytesStoreSupplier storeSupplier)
  37         {
  38                 StreamsBuilder builder = new StreamsBuilder();
  39
  40                 builder
  41                                 .<Key, Entry>stream(inputTopic)
  42                                 .map((key, entry) -> new KeyValue<>(User.of(key.getUser()), entry))
  43                                 .groupByKey()
  44                                 .aggregate(
  45                                                 () -> new Ranking(),
  46                                                 (user, entry, ranking) -> ranking.add(entry),
  47                                                 Materialized.as(storeSupplier))
  48                                 .toStream()
  49                                 .to(outputTopic);
  50
  51                 Topology topology = builder.build();
  52                 log.info("\n\n{}", topology.describe());
  53
  54                 return topology;
  55         }
  56
  57         ReadOnlyKeyValueStore<User, Ranking> getStore(String name)
  58         {
  59                 return streams.store(StoreQueryParameters.fromNameAndType(name, QueryableStoreTypes.keyValueStore()));
  60         }
  61
  62         public void start()
  63         {
  64                 log.info("Starting Stream-Processor");
  65                 streams.start();
  66         }
  67
  68         public void stop()
  69         {
  70                 log.info("Stopping Stream-Processor");
  71                 streams.close();
  72         }
  73 }