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.common.serialization.Serdes;
   5 import org.apache.kafka.streams.*;
   6 import org.apache.kafka.streams.kstream.Consumed;
   7 import org.apache.kafka.streams.kstream.KStream;
   8 import org.apache.kafka.streams.kstream.Materialized;
   9 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
  10 import org.apache.kafka.streams.state.QueryableStoreTypes;
  11 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  12
  13 import java.util.Properties;
  14
  15
  16 @Slf4j
  17 public class CounterStreamProcessor
  18 {
  19         public static final String STORE_NAME = "counter";
  20
  21
  22         public final KafkaStreams streams;
  23
  24
  25         public CounterStreamProcessor(
  26                         String inputTopic,
  27                         String outputTopic,
  28                         Properties properties,
  29                         KeyValueBytesStoreSupplier storeSupplier)
  30         {
  31                 Topology topology = CounterStreamProcessor.buildTopology(
  32                                 inputTopic,
  33                                 outputTopic,
  34                                 storeSupplier);
  35
  36                 streams = new KafkaStreams(topology, properties);
  37         }
  38
  39         static Topology buildTopology(
  40                         String inputTopic,
  41                         String outputTopic,
  42                         KeyValueBytesStoreSupplier storeSupplier)
  43         {
  44                 StreamsBuilder builder = new StreamsBuilder();
  45
  46                 KStream<String, Word> source = builder.stream(
  47                                 inputTopic,
  48                                 Consumed.with(Serdes.String(), null));
  49
  50                 source
  51                                 .map((key, word) -> new KeyValue<>(word, word))
  52                                 .groupByKey()
  53                                 .count(Materialized.as(storeSupplier))
  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 }