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.KafkaStreams;
   5 import org.apache.kafka.streams.KeyValue;
   6 import org.apache.kafka.streams.StreamsBuilder;
   7 import org.apache.kafka.streams.Topology;
   8 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
   9 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  10
  11 import java.util.Properties;
  12
  13
  14 @Slf4j
  15 public class Top10StreamProcessor
  16 {
  17         public final KafkaStreams streams;
  18
  19
  20         public Top10StreamProcessor(
  21                         String inputTopic,
  22                         String outputTopic,
  23                         Properties props)
  24         {
  25                 Topology topology = Top10StreamProcessor.buildTopology(
  26                                 inputTopic,
  27                                 outputTopic,
  28                                 null);
  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                                 .toStream()
  48                                 .to(outputTopic);
  49
  50                 Topology topology = builder.build();
  51                 log.info("\n\n{}", topology.describe());
  52
  53                 return topology;
  54         }
  55
  56         ReadOnlyKeyValueStore<User, Ranking> getStore(String name)
  57         {
  58                 return null;
  59         }
  60
  61         public void start()
  62         {
  63                 log.info("Starting Stream-Processor");
  64                 streams.start();
  65         }
  66
  67         public void stop()
  68         {
  69                 log.info("Stopping Stream-Processor");
  70                 streams.close();
  71         }
  72 }