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.*;
  10 import org.apache.kafka.streams.kstream.KStream;
  11 import org.apache.kafka.streams.kstream.KTable;
  12 import org.apache.kafka.streams.kstream.Materialized;
  13 import org.apache.kafka.streams.state.HostInfo;
  14 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
  15 import org.apache.kafka.streams.state.QueryableStoreTypes;
  16 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  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, String>> storeParameters;
  31         public final ObjectMapper mapper;
  32
  33
  34         public QueryStreamProcessor(
  35                         Properties props,
  36                         HostInfo applicationServer,
  37                         String usersInputTopic,
  38                         String rankingInputTopic,
  39                         KeyValueBytesStoreSupplier storeSupplier,
  40                         ObjectMapper mapper)
  41         {
  42                 Topology topology = buildTopology(
  43                                 usersInputTopic,
  44                                 rankingInputTopic,
  45                                 storeSupplier,
  46                                 mapper);
  47                 streams = new KafkaStreams(topology, props);
  48                 hostInfo = applicationServer;
  49                 storeParameters = StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore());;
  50                 this.mapper = mapper;
  51         }
  52
  53         static Topology buildTopology(
  54                         String usersInputTopic,
  55                         String rankingInputTopic,
  56                         KeyValueBytesStoreSupplier storeSupplier,
  57                         ObjectMapper mapper)
  58         {
  59                 StreamsBuilder builder = new StreamsBuilder();
  60
  61                 KTable<String, String> users = builder.table(usersInputTopic);
  62                 KStream<String, String> rankings = builder.stream(rankingInputTopic);
  63
  64                 rankings
  65                                 .join(users, (rankingJson, userJson) ->
  66                                 {
  67                                         try
  68                                         {
  69                                                 Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
  70                                                 User user = mapper.readValue(userJson, User.class);
  71
  72                                                 return mapper.writeValueAsString(
  73                                                                 UserRanking.of(
  74                                                                                 user.getFirstName(),
  75                                                                                 user.getLastName(),
  76                                                                                 ranking.getEntries()));
  77                                         }
  78                                         catch (JsonProcessingException e)
  79                                         {
  80                                                 throw new RuntimeException(e);
  81                                         }
  82                                 })
  83                                 .toTable(Materialized.as(storeSupplier));
  84
  85                 Topology topology = builder.build();
  86                 log.info("\n\n{}", topology.describe());
  87
  88                 return topology;
  89         }
  90
  91         ReadOnlyKeyValueStore<String, UserRanking> getStore()
  92         {
  93                 return streams.store(storeParameters);
  94         }
  95
  96         public Optional<URI> getRedirect(String username)
  97         {
  98                 KeyQueryMetadata metadata = streams.queryMetadataForKey(STORE_NAME, username, Serdes.String().serializer());
  99                 HostInfo activeHost = metadata.activeHost();
 100                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
 101
 102                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
 103                 {
 104                         return Optional.empty();
 105                 }
 106
 107                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
 108                 log.debug("Redirecting to {}", location);
 109                 return Optional.of(location);
 110         }
 111
 112         public Optional<UserRanking> getUserRanking(String username)
 113         {
 114                 return
 115                                 Optional
 116                                                 .ofNullable(getStore().get(username))
 117                                                 .map(json ->
 118                                                 {
 119                                                         try
 120                                                         {
 121                                                                 return mapper.readValue(json, UserRanking.class);
 122                                                         }
 123                                                         catch (JsonProcessingException e)
 124                                                         {
 125                                                                 throw new RuntimeException(e);
 126                                                         }
 127                                                 });
 128         }
 129
 130         @PostConstruct
 131         public void start()
 132         {
 133                 log.info("Starting Stream-Processor");
 134                 streams.start();
 135         }
 136
 137         @PreDestroy
 138         public void stop()
 139         {
 140                 log.info("Stopping Stream-Processor");
 141                 streams.close();
 142         }
 143 }