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.KStream;
   9 import org.apache.kafka.streams.kstream.KTable;
  10 import org.apache.kafka.streams.kstream.Materialized;
  11 import org.apache.kafka.streams.state.HostInfo;
  12 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
  13 import org.apache.kafka.streams.state.QueryableStoreTypes;
  14 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  15 import org.springframework.kafka.support.serializer.JsonSerde;
  16
  17 import java.net.URI;
  18 import java.util.Optional;
  19 import java.util.Properties;
  20
  21
  22 @Slf4j
  23 public class QueryStreamProcessor
  24 {
  25         public static final String STORE_NAME = "rankings-by-username";
  26
  27         public final KafkaStreams streams;
  28         public final HostInfo hostInfo;
  29         public final StoreQueryParameters<ReadOnlyKeyValueStore<String, UserRanking>> storeParameters;
  30
  31
  32         public QueryStreamProcessor(
  33                         Properties props,
  34                         HostInfo applicationServer,
  35                         String usersInputTopic,
  36                         String rankingInputTopic,
  37                         KeyValueBytesStoreSupplier storeSupplier)
  38         {
  39                 Topology topology = buildTopology(
  40                                 usersInputTopic,
  41                                 rankingInputTopic,
  42                                 storeSupplier);
  43                 streams = new KafkaStreams(topology, props);
  44                 hostInfo = applicationServer;
  45                 storeParameters = StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore());;
  46         }
  47
  48         static Topology buildTopology(
  49                         String usersInputTopic,
  50                         String rankingInputTopic,
  51                         KeyValueBytesStoreSupplier storeSupplier)
  52         {
  53                 StreamsBuilder builder = new StreamsBuilder();
  54
  55                 KTable<String, User> users = builder
  56                                 .stream(usersInputTopic)
  57                                 .toTable(Materialized.with(null, new JsonSerde().copyWithType(User.class)));
  58                 KStream<String, Ranking> rankings = builder.stream(rankingInputTopic);
  59
  60                 rankings
  61                                 .join(users, (ranking, user) -> UserRanking.of(
  62                                                 user.getFirstName(),
  63                                                 user.getLastName(),
  64                                                 ranking.getEntries()))
  65                                 .toTable(
  66                                                 Materialized
  67                                                                 .<String, UserRanking>as(storeSupplier)
  68                                                                 .withValueSerde(new JsonSerde().copyWithType(UserRanking.class)));
  69
  70                 Topology topology = builder.build();
  71                 log.info("\n\n{}", topology.describe());
  72
  73                 return topology;
  74         }
  75
  76         ReadOnlyKeyValueStore<String, UserRanking> getStore()
  77         {
  78                 return streams.store(storeParameters);
  79         }
  80
  81         public Optional<URI> getRedirect(String username)
  82         {
  83                 KeyQueryMetadata metadata = streams.queryMetadataForKey(STORE_NAME, username, Serdes.String().serializer());
  84                 HostInfo activeHost = metadata.activeHost();
  85                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
  86
  87                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
  88                 {
  89                         return Optional.empty();
  90                 }
  91
  92                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
  93                 log.debug("Redirecting to {}", location);
  94                 return Optional.of(location);
  95         }
  96
  97         public Optional<UserRanking> getUserRanking(String username)
  98         {
  99                 return Optional.ofNullable(getStore().get(username));
 100         }
 101
 102         @PostConstruct
 103         public void start()
 104         {
 105                 log.info("Starting Stream-Processor");
 106                 streams.start();
 107         }
 108
 109         @PreDestroy
 110         public void stop()
 111         {
 112                 log.info("Stopping Stream-Processor");
 113                 streams.close();
 114         }
 115 }