juplo.de Git - demos/kafka/wordcount/blob - src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java

   1 package de.juplo.kafka.wordcount.counter;
   2
   3 import lombok.extern.slf4j.Slf4j;
   4 import org.apache.kafka.streams.*;
   5 import org.apache.kafka.streams.kstream.KStream;
   6 import org.apache.kafka.streams.kstream.Materialized;
   7 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
   8 import org.apache.kafka.streams.state.QueryableStoreTypes;
   9 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  10 import org.springframework.kafka.support.serializer.JsonSerde;
  11
  12 import java.util.Properties;
  13
  14
  15 @Slf4j
  16 public class CounterStreamProcessor
  17 {
  18         public static final String STORE_NAME = "counter";
  19
  20
  21         public final KafkaStreams streams;
  22
  23
  24         public CounterStreamProcessor(
  25                         String inputTopic,
  26                         String outputTopic,
  27                         Properties properties,
  28                         KeyValueBytesStoreSupplier storeSupplier)
  29         {
  30                 Topology topology = CounterStreamProcessor.buildTopology(
  31                                 inputTopic,
  32                                 outputTopic,
  33                                 storeSupplier);
  34
  35                 streams = new KafkaStreams(topology, properties);
  36         }
  37
  38         static Topology buildTopology(
  39                         String inputTopic,
  40                         String outputTopic,
  41                         KeyValueBytesStoreSupplier storeSupplier)
  42         {
  43                 StreamsBuilder builder = new StreamsBuilder();
  44
  45                 KStream<User, Word> source = builder.stream(inputTopic);
  46
  47                 source
  48                                 .map((key, word) -> new KeyValue<>(word, word))
  49                                 .groupByKey()
  50                                 .count(
  51                                                 Materialized
  52                                                                 .<Word, Long>as(storeSupplier)
  53                                                                 .withKeySerde(new JsonSerde<>().copyWithType(Word.class).forKeys()))
  54                                 .toStream()
  55                                 .map((word, counter) -> new KeyValue<>(word, WordCounter.of(word, counter)))
  56                                 .to(outputTopic);
  57
  58                 Topology topology = builder.build();
  59                 log.info("\n\n{}", topology.describe());
  60
  61                 return topology;
  62         }
  63
  64         ReadOnlyKeyValueStore<Word, Long> getStore()
  65         {
  66                 return streams.store(StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore()));
  67         }
  68
  69         public void start()
  70         {
  71                 log.info("Starting Stream-Processor");
  72                 streams.start();
  73         }
  74
  75         public void stop()
  76         {
  77                 log.info("Stopping Stream-Processor");
  78                 streams.close();
  79         }
  80 }