juplo.de Git - demos/kafka/wordcount/blob - src/main/java/de/juplo/kafka/wordcount/query/QueryStreamProcessor.java

   1 package de.juplo.kafka.wordcount.query;
   2
   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;
  17
  18 import java.net.URI;
  19 import java.util.Optional;
  20 import java.util.Properties;
  21
  22
  23 @Slf4j
  24 public class QueryStreamProcessor
  25 {
  26         public static final String USER_STORE_NAME = "users";
  27         public static final String RANKING_STORE_NAME = "rankings";
  28
  29         public final KafkaStreams streams;
  30         public final HostInfo hostInfo;
  31         public final StoreQueryParameters<ReadOnlyKeyValueStore<String, UserRanking>> storeParameters;
  32
  33
  34         public QueryStreamProcessor(
  35                         Properties props,
  36                         HostInfo applicationServer,
  37                         String usersInputTopic,
  38                         String rankingInputTopic,
  39                         KeyValueBytesStoreSupplier userStoreSupplier,
  40                         KeyValueBytesStoreSupplier rankingStoreSupplier)
  41         {
  42                 Topology topology = buildTopology(
  43                                 usersInputTopic,
  44                                 rankingInputTopic,
  45                                 userStoreSupplier,
  46                                 rankingStoreSupplier);
  47                 streams = new KafkaStreams(topology, props);
  48                 hostInfo = applicationServer;
  49                 storeParameters = StoreQueryParameters.fromNameAndType(RANKING_STORE_NAME, QueryableStoreTypes.keyValueStore());;
  50         }
  51
  52         static Topology buildTopology(
  53                         String usersInputTopic,
  54                         String rankingInputTopic,
  55                         KeyValueBytesStoreSupplier userStoreSupplier,
  56                         KeyValueBytesStoreSupplier rankingStoreSupplier)
  57         {
  58                 StreamsBuilder builder = new StreamsBuilder();
  59
  60                 KTable<String, User> users = builder
  61                                 .stream(
  62                                                 usersInputTopic,
  63                                                 Consumed.with(null, new JsonSerde().copyWithType(User.class)))
  64                                 .toTable(
  65                                                 Materialized
  66                                                                 .<String, User>as(userStoreSupplier)
  67                                                                 .withKeySerde(Serdes.String())
  68                                                                 .withValueSerde(new JsonSerde().copyWithType(User.class)));
  69                 KStream<String, Ranking> rankings = builder.stream(rankingInputTopic);
  70
  71                 rankings
  72                                 .join(users, (ranking, user) -> UserRanking.of(
  73                                                 user.getFirstName(),
  74                                                 user.getLastName(),
  75                                                 ranking.getEntries()))
  76                                 .toTable(
  77                                                 Materialized
  78                                                                 .<String, UserRanking>as(rankingStoreSupplier)
  79                                                                 .withValueSerde(new JsonSerde().copyWithType(UserRanking.class)));
  80
  81                 Topology topology = builder.build();
  82                 log.info("\n\n{}", topology.describe());
  83
  84                 return topology;
  85         }
  86
  87         ReadOnlyKeyValueStore<String, UserRanking> getStore()
  88         {
  89                 return streams.store(storeParameters);
  90         }
  91
  92         public Optional<URI> getRedirect(String username)
  93         {
  94                 KeyQueryMetadata metadata = streams.queryMetadataForKey(RANKING_STORE_NAME, username, Serdes.String().serializer());
  95                 HostInfo activeHost = metadata.activeHost();
  96                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
  97
  98                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
  99                 {
 100                         return Optional.empty();
 101                 }
 102
 103                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
 104                 log.debug("Redirecting to {}", location);
 105                 return Optional.of(location);
 106         }
 107
 108         public Optional<UserRanking> getUserRanking(String username)
 109         {
 110                 return Optional.ofNullable(getStore().get(username));
 111         }
 112
 113         @PostConstruct
 114         public void start()
 115         {
 116                 log.info("Starting Stream-Processor");
 117                 streams.start();
 118         }
 119
 120         @PreDestroy
 121         public void stop()
 122         {
 123                 log.info("Stopping Stream-Processor");
 124                 streams.close();
 125         }
 126 }