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.*;
   9 import org.apache.kafka.streams.state.HostInfo;
  10 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
  11 import org.apache.kafka.streams.state.QueryableStoreTypes;
  12 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  13 import org.springframework.kafka.support.serializer.JsonSerde;
  14
  15 import java.net.URI;
  16 import java.util.Optional;
  17 import java.util.Properties;
  18
  19
  20 @Slf4j
  21 public class QueryStreamProcessor
  22 {
  23         public static final String USER_STORE_NAME = "users";
  24         public static final String RANKING_STORE_NAME = "rankings";
  25
  26         public final KafkaStreams streams;
  27         public final HostInfo hostInfo;
  28         public final StoreQueryParameters<ReadOnlyKeyValueStore<String, UserRanking>> storeParameters;
  29
  30
  31         public QueryStreamProcessor(
  32                         Properties props,
  33                         HostInfo applicationServer,
  34                         String usersInputTopic,
  35                         String rankingInputTopic,
  36                         KeyValueBytesStoreSupplier userStoreSupplier,
  37                         KeyValueBytesStoreSupplier rankingStoreSupplier)
  38         {
  39                 Topology topology = buildTopology(
  40                                 usersInputTopic,
  41                                 rankingInputTopic,
  42                                 userStoreSupplier,
  43                                 rankingStoreSupplier);
  44                 streams = new KafkaStreams(topology, props);
  45                 hostInfo = applicationServer;
  46                 storeParameters = StoreQueryParameters.fromNameAndType(RANKING_STORE_NAME, QueryableStoreTypes.keyValueStore());;
  47         }
  48
  49         static Topology buildTopology(
  50                         String usersInputTopic,
  51                         String rankingInputTopic,
  52                         KeyValueBytesStoreSupplier userStoreSupplier,
  53                         KeyValueBytesStoreSupplier rankingStoreSupplier)
  54         {
  55                 StreamsBuilder builder = new StreamsBuilder();
  56
  57                 KTable<String, User> users = builder
  58                                 .stream(
  59                                                 usersInputTopic,
  60                                                 Consumed.with(Serdes.String(), new JsonSerde().copyWithType(User.class)))
  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
  67                                 .<Key, Ranking>stream(rankingInputTopic)
  68                                 .map((key, value) -> new KeyValue<>(key.getUsername(), value));
  69
  70                 rankings
  71                                 .join(users, (ranking, user) -> UserRanking.of(
  72                                                 user.getFirstName(),
  73                                                 user.getLastName(),
  74                                                 ranking.getEntries()),
  75                                                 Joined.keySerde(Serdes.String()))
  76                                 .toTable(
  77                                                 Materialized
  78                                                                 .<String, UserRanking>as(rankingStoreSupplier)
  79                                                                 .withKeySerde(Serdes.String())
  80                                                                 .withValueSerde(new JsonSerde().copyWithType(UserRanking.class)));
  81
  82                 Topology topology = builder.build();
  83                 log.info("\n\n{}", topology.describe());
  84
  85                 return topology;
  86         }
  87
  88         ReadOnlyKeyValueStore<String, UserRanking> getStore()
  89         {
  90                 return streams.store(storeParameters);
  91         }
  92
  93         public Optional<URI> getRedirect(String username)
  94         {
  95                 KeyQueryMetadata metadata = streams.queryMetadataForKey(RANKING_STORE_NAME, username, Serdes.String().serializer());
  96                 HostInfo activeHost = metadata.activeHost();
  97                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
  98
  99                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
 100                 {
 101                         return Optional.empty();
 102                 }
 103
 104                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
 105                 log.debug("Redirecting to {}", location);
 106                 return Optional.of(location);
 107         }
 108
 109         public Optional<UserRanking> getUserRanking(String username)
 110         {
 111                 return Optional.ofNullable(getStore().get(username));
 112         }
 113
 114         @PostConstruct
 115         public void start()
 116         {
 117                 log.info("Starting Stream-Processor");
 118                 streams.start();
 119         }
 120
 121         @PreDestroy
 122         public void stop()
 123         {
 124                 log.info("Stopping Stream-Processor");
 125                 streams.close();
 126         }
 127 }