1 package de.juplo.kafka.wordcount.counter;
3 import com.fasterxml.jackson.databind.ObjectMapper;
4 import lombok.extern.slf4j.Slf4j;
5 import org.apache.kafka.common.serialization.Serdes;
6 import org.apache.kafka.streams.KafkaStreams;
7 import org.apache.kafka.streams.KeyValue;
8 import org.apache.kafka.streams.StreamsBuilder;
9 import org.apache.kafka.streams.Topology;
10 import org.apache.kafka.streams.kstream.KStream;
11 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
12 import org.apache.kafka.streams.kstream.*;
14 import java.util.Properties;
18 public class CounterStreamProcessor
20 public final KafkaStreams streams;
23 public CounterStreamProcessor(
26 Properties properties,
27 KeyValueBytesStoreSupplier storeSupplier,
30 Topology topology = CounterStreamProcessor.buildTopology(
36 streams = new KafkaStreams(topology, properties);
39 static Topology buildTopology(
42 KeyValueBytesStoreSupplier storeSupplier,
45 StreamsBuilder builder = new StreamsBuilder();
47 KStream<String, Word> source = builder.stream(
49 Consumed.with(Serdes.String(), null));
52 .map((key, word) -> new KeyValue<>(word, word))
54 .count(Materialized.as(storeSupplier))
56 .map((word, count) -> new KeyValue<>(word, WordCount.of(word, count)))
59 Topology topology = builder.build();
60 log.info("\n\n{}", topology.describe());
67 log.info("Starting Stream-Processor");
73 log.info("Stopping Stream-Processor");