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 com.fasterxml.jackson.core.JsonProcessingException;
   4 import com.fasterxml.jackson.databind.ObjectMapper;
   5 import jakarta.annotation.PostConstruct;
   6 import jakarta.annotation.PreDestroy;
   7 import lombok.extern.slf4j.Slf4j;
   8 import org.apache.kafka.common.serialization.Serdes;
   9 import org.apache.kafka.streams.KafkaStreams;
  10 import org.apache.kafka.streams.KeyQueryMetadata;
  11 import org.apache.kafka.streams.StoreQueryParameters;
  12 import org.apache.kafka.streams.StreamsBuilder;
  13 import org.apache.kafka.streams.kstream.KStream;
  14 import org.apache.kafka.streams.kstream.KTable;
  15 import org.apache.kafka.streams.kstream.Materialized;
  16 import org.apache.kafka.streams.state.HostInfo;
  17 import org.apache.kafka.streams.state.QueryableStoreTypes;
  18 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  19
  20 import java.net.URI;
  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, String>> storeParameters;
  33         public final ObjectMapper mapper;
  34
  35
  36         public QueryStreamProcessor(
  37                         Properties props,
  38                         HostInfo applicationServer,
  39                         String usersInputTopic,
  40                         String rankingInputTopic,
  41                         ObjectMapper mapper)
  42         {
  43                 StreamsBuilder builder = new StreamsBuilder();
  44
  45                 KTable<String, String> users = builder.table(usersInputTopic);
  46                 KStream<String, String> rankings = builder.stream(rankingInputTopic);
  47
  48                 rankings
  49                                 .join(users, (rankingJson, userJson) ->
  50                                 {
  51                                         try
  52                                         {
  53                                                 Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
  54                                                 User user = mapper.readValue(userJson, User.class);
  55
  56                                                 return mapper.writeValueAsString(
  57                                                                 UserRanking.of(
  58                                                                                 user.getFirstName(),
  59                                                                                 user.getLastName(),
  60                                                                                 ranking.getEntries()));
  61                                         }
  62                                         catch (JsonProcessingException e)
  63                                         {
  64                                                 throw new RuntimeException(e);
  65                                         }
  66                                 })
  67                                 .toTable(Materialized.as(STORE_NAME));
  68
  69                 streams = new KafkaStreams(builder.build(), props);
  70                 hostInfo = applicationServer;
  71                 storeParameters = StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore());;
  72                 this.mapper = mapper;
  73         }
  74
  75         public Optional<URI> getRedirect(String username)
  76         {
  77                 KeyQueryMetadata metadata = streams.queryMetadataForKey(STORE_NAME, username, Serdes.String().serializer());
  78                 HostInfo activeHost = metadata.activeHost();
  79                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
  80
  81                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
  82                 {
  83                         return Optional.empty();
  84                 }
  85
  86                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
  87                 log.debug("Redirecting to {}", location);
  88                 return Optional.of(location);
  89         }
  90
  91         public Optional<UserRanking> getUserRanking(String username)
  92         {
  93                 return
  94                                 Optional
  95                                                 .ofNullable(streams.store(storeParameters).get(username))
  96                                                 .map(json ->
  97                                                 {
  98                                                         try
  99                                                         {
 100                                                                 return mapper.readValue(json, UserRanking.class);
 101                                                         }
 102                                                         catch (JsonProcessingException e)
 103                                                         {
 104                                                                 throw new RuntimeException(e);
 105                                                         }
 106                                                 });
 107         }
 108
 109         @PostConstruct
 110         public void start()
 111         {
 112                 log.info("Starting Stream-Processor");
 113                 streams.start();
 114         }
 115
 116         @PreDestroy
 117         public void stop()
 118         {
 119                 log.info("Stopping Stream-Processor");
 120                 streams.close();
 121         }
 122 }