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(Serdes.String(), 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
  70                                 .<Key, Ranking>stream(rankingInputTopic)
  71                                 .map((key, value) -> new KeyValue<>(key.getUsername(), value));
  72
  73                 rankings
  74                                 .join(users, (ranking, user) -> UserRanking.of(
  75                                                 user.getFirstName(),
  76                                                 user.getLastName(),
  77                                                 ranking.getEntries()))
  78                                 .toTable(
  79                                                 Materialized
  80                                                                 .<String, UserRanking>as(rankingStoreSupplier)
  81                                                                 .withKeySerde(Serdes.String())
  82                                                                 .withValueSerde(new JsonSerde().copyWithType(UserRanking.class)));
  83
  84                 Topology topology = builder.build();
  85                 log.info("\n\n{}", topology.describe());
  86
  87                 return topology;
  88         }
  89
  90         ReadOnlyKeyValueStore<String, UserRanking> getStore()
  91         {
  92                 return streams.store(storeParameters);
  93         }
  94
  95         public Optional<URI> getRedirect(String username)
  96         {
  97                 KeyQueryMetadata metadata = streams.queryMetadataForKey(RANKING_STORE_NAME, username, Serdes.String().serializer());
  98                 HostInfo activeHost = metadata.activeHost();
  99                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
 100
 101                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
 102                 {
 103                         return Optional.empty();
 104                 }
 105
 106                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
 107                 log.debug("Redirecting to {}", location);
 108                 return Optional.of(location);
 109         }
 110
 111         public Optional<UserRanking> getUserRanking(String username)
 112         {
 113                 return Optional.ofNullable(getStore().get(username));
 114         }
 115
 116         @PostConstruct
 117         public void start()
 118         {
 119                 log.info("Starting Stream-Processor");
 120                 streams.start();
 121         }
 122
 123         @PreDestroy
 124         public void stop()
 125         {
 126                 log.info("Stopping Stream-Processor");
 127                 streams.close();
 128         }
 129 }