1 package de.juplo.kafka.wordcount.query;
3 import jakarta.annotation.PostConstruct;
4 import jakarta.annotation.PreDestroy;
5 import lombok.extern.slf4j.Slf4j;
6 import org.apache.kafka.common.serialization.Serdes;
7 import org.apache.kafka.streams.*;
8 import org.apache.kafka.streams.kstream.Consumed;
9 import org.apache.kafka.streams.kstream.KStream;
10 import org.apache.kafka.streams.kstream.KTable;
11 import org.apache.kafka.streams.kstream.Materialized;
12 import org.apache.kafka.streams.state.HostInfo;
13 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
14 import org.apache.kafka.streams.state.QueryableStoreTypes;
15 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
16 import org.springframework.kafka.support.serializer.JsonSerde;
19 import java.util.Optional;
20 import java.util.Properties;
24 public class QueryStreamProcessor
26 public static final String STORE_NAME = "rankings-by-username";
28 public final KafkaStreams streams;
29 public final HostInfo hostInfo;
30 public final StoreQueryParameters<ReadOnlyKeyValueStore<String, UserRanking>> storeParameters;
33 public QueryStreamProcessor(
35 HostInfo applicationServer,
36 String usersInputTopic,
37 String rankingInputTopic,
38 KeyValueBytesStoreSupplier storeSupplier)
40 Topology topology = buildTopology(
44 streams = new KafkaStreams(topology, props);
45 hostInfo = applicationServer;
46 storeParameters = StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore());;
49 static Topology buildTopology(
50 String usersInputTopic,
51 String rankingInputTopic,
52 KeyValueBytesStoreSupplier storeSupplier)
54 StreamsBuilder builder = new StreamsBuilder();
56 KTable<String, User> users = builder.table(usersInputTopic);
57 KStream<String, Ranking> rankings = builder.stream(rankingInputTopic);
60 .join(users, (ranking, user) -> UserRanking.of(
63 ranking.getEntries()))
66 .<String, UserRanking>as(storeSupplier)
67 .withValueSerde(new JsonSerde().copyWithType(UserRanking.class)));
69 Topology topology = builder.build();
70 log.info("\n\n{}", topology.describe());
75 ReadOnlyKeyValueStore<String, UserRanking> getStore()
77 return streams.store(storeParameters);
80 public Optional<URI> getRedirect(String username)
82 KeyQueryMetadata metadata = streams.queryMetadataForKey(STORE_NAME, username, Serdes.String().serializer());
83 HostInfo activeHost = metadata.activeHost();
84 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
86 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
88 return Optional.empty();
91 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
92 log.debug("Redirecting to {}", location);
93 return Optional.of(location);
96 public Optional<UserRanking> getUserRanking(String username)
98 return Optional.ofNullable(getStore().get(username));
104 log.info("Starting Stream-Processor");
111 log.info("Stopping Stream-Processor");