1 package de.juplo.kafka.wordcount.counter;
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;
11 import java.util.Properties;
15 public class CounterStreamProcessor
17 public static final String STORE_NAME = "counter";
20 public final KafkaStreams streams;
23 public CounterStreamProcessor(
26 Properties properties,
27 KeyValueBytesStoreSupplier storeSupplier)
29 Topology topology = CounterStreamProcessor.buildTopology(
34 streams = new KafkaStreams(topology, properties);
37 static Topology buildTopology(
40 KeyValueBytesStoreSupplier storeSupplier)
42 StreamsBuilder builder = new StreamsBuilder();
44 KStream<User, Word> source = builder.stream(inputTopic);
47 .map((key, word) -> new KeyValue<>(word, word))
49 .count(Materialized.as(storeSupplier))
51 .map((word, counter) -> new KeyValue<>(word, WordCounter.of(word, counter)))
54 Topology topology = builder.build();
55 log.info("\n\n{}", topology.describe());
60 ReadOnlyKeyValueStore<Word, Long> getStore()
62 return streams.store(StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore()));
67 log.info("Starting Stream-Processor");
73 log.info("Stopping Stream-Processor");