juplo.de Git - demos/kafka/deduplication/blob - src/main/java/de/juplo/demo/kafka/deduplication/Deduplicator.java

   1 package de.juplo.demo.kafka.deduplication;
   2
   3
   4 import org.apache.kafka.common.serialization.Serdes;
   5 import org.apache.kafka.streams.KafkaStreams;
   6 import org.apache.kafka.streams.StreamsBuilder;
   7 import org.apache.kafka.streams.Topology;
   8 import org.apache.kafka.streams.kstream.ValueTransformerWithKey;
   9 import org.apache.kafka.streams.kstream.ValueTransformerWithKeySupplier;
  10 import org.apache.kafka.streams.state.KeyValueStore;
  11 import org.apache.kafka.streams.state.StoreBuilder;
  12 import org.apache.kafka.streams.state.Stores;
  13 import org.slf4j.Logger;
  14 import org.slf4j.LoggerFactory;
  15 import org.springframework.stereotype.Component;
  16
  17 import javax.annotation.PostConstruct;
  18 import javax.annotation.PreDestroy;
  19 import java.time.Duration;
  20 import java.util.Properties;
  21
  22
  23 @Component
  24 public class Deduplicator
  25 {
  26   final static Logger LOG = LoggerFactory.getLogger(Deduplicator.class);
  27
  28   public final KafkaStreams streams;
  29
  30
  31   public Deduplicator()
  32   {
  33     Properties properties = new Properties();
  34     properties.put("bootstrap.servers", "kafka:9092");
  35     properties.put("application.id", "streams-deduplicator");
  36     properties.put("default.key.serde", Serdes.StringSerde.class);
  37     properties.put("default.value.serde", Serdes.StringSerde.class);
  38
  39     StreamsBuilder builder = new StreamsBuilder();
  40
  41     // Create state-store for sequence numbers
  42     StoreBuilder<KeyValueStore<Integer,Long>> store =
  43         Stores.keyValueStoreBuilder(
  44             Stores.persistentKeyValueStore(DeduplicationTransformer.STORE),
  45             Serdes.Integer(),
  46             Serdes.Long());
  47     // register store
  48     builder.addStateStore(store);
  49
  50     builder
  51         .<String, String>stream("input")
  52         .flatTransformValues(
  53             new ValueTransformerWithKeySupplier<String, String, Iterable<String>>()
  54             {
  55               @Override
  56               public ValueTransformerWithKey<String, String, Iterable<String>> get()
  57               {
  58                 return new DeduplicationTransformer();
  59               }
  60             },
  61             DeduplicationTransformer.STORE)
  62         .to("output");
  63
  64     Topology topology = builder.build();
  65     streams = new KafkaStreams(topology, properties);
  66     streams.setUncaughtExceptionHandler((Thread t, Throwable e) ->
  67     {
  68       LOG.error("Unexpected error in thread {}: {}", t, e.toString());
  69       try
  70       {
  71         streams.close(Duration.ofSeconds(5));
  72       }
  73       catch (Exception ex)
  74       {
  75         LOG.error("Could not close KafkaStreams!", ex);
  76       }
  77     });
  78   }
  79
  80
  81   @PostConstruct
  82   public void start()
  83   {
  84     streams.start();
  85   }
  86
  87   @PreDestroy
  88   public void stop()
  89   {
  90     streams.close(Duration.ofSeconds(5));
  91   }
  92 }