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