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.JsonDeserializer;
  17 import org.springframework.kafka.support.serializer.JsonSerde;
  18
  19 import java.net.URI;
  20 import java.util.Map;
  21 import java.util.Optional;
  22 import java.util.Properties;
  23
  24
  25 @Slf4j
  26 public class QueryStreamProcessor
  27 {
  28         public static final String STORE_NAME = "rankings-by-username";
  29
  30         public final KafkaStreams streams;
  31         public final HostInfo hostInfo;
  32         public final StoreQueryParameters<ReadOnlyKeyValueStore<String, UserRanking>> storeParameters;
  33
  34
  35         public QueryStreamProcessor(
  36                         Properties props,
  37                         HostInfo applicationServer,
  38                         String usersInputTopic,
  39                         String rankingInputTopic,
  40                         KeyValueBytesStoreSupplier storeSupplier)
  41         {
  42                 Topology topology = buildTopology(
  43                                 usersInputTopic,
  44                                 rankingInputTopic,
  45                                 storeSupplier);
  46                 streams = new KafkaStreams(topology, props);
  47                 hostInfo = applicationServer;
  48                 storeParameters = StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore());;
  49         }
  50
  51         static Topology buildTopology(
  52                         String usersInputTopic,
  53                         String rankingInputTopic,
  54                         KeyValueBytesStoreSupplier storeSupplier)
  55         {
  56                 StreamsBuilder builder = new StreamsBuilder();
  57
  58                 JsonSerde valueSerde = new JsonSerde();
  59                 valueSerde.configure(Map.of(
  60                                 JsonDeserializer.TYPE_MAPPINGS,
  61                                 "user:" + Key.class.getName() + "," +
  62                                                 "ranking:" + Ranking.class.getName() + "," +
  63                                                 "userdata:" + User.class.getName() + "," +
  64                                                 "userranking:" + UserRanking.class.getName()
  65                 ), false);
  66                 KTable<String, User> users = builder.table(
  67                                 usersInputTopic,
  68                                 Consumed.with(null, valueSerde.copyWithType(User.class))
  69                                 );
  70                 KStream<String, Ranking> rankings = builder.stream(rankingInputTopic);
  71
  72                 rankings
  73                                 .join(users, (ranking, user) -> UserRanking.of(
  74                                                 user.getFirstName(),
  75                                                 user.getLastName(),
  76                                                 ranking.getEntries()))
  77                                 .toTable(
  78                                                 Materialized
  79                                                                 .<String, UserRanking>as(storeSupplier)
  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(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 }