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