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.QueryableStoreTypes;
  15 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  16
  17 import java.net.URI;
  18 import java.util.Optional;
  19 import java.util.Properties;
  20
  21
  22 @Slf4j
  23 public class QueryStreamProcessor
  24 {
  25         public static final String STORE_NAME = "rankings-by-username";
  26
  27         public final KafkaStreams streams;
  28         public final HostInfo hostInfo;
  29         public final StoreQueryParameters<ReadOnlyKeyValueStore<String, String>> storeParameters;
  30         public final ObjectMapper mapper;
  31
  32
  33         public QueryStreamProcessor(
  34                         Properties props,
  35                         HostInfo applicationServer,
  36                         String usersInputTopic,
  37                         String rankingInputTopic,
  38                         ObjectMapper mapper)
  39         {
  40                 Topology topology = buildTopology(usersInputTopic, rankingInputTopic, mapper);
  41                 streams = new KafkaStreams(topology, props);
  42                 hostInfo = applicationServer;
  43                 storeParameters = StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore());;
  44                 this.mapper = mapper;
  45         }
  46
  47         static Topology buildTopology(
  48                         String usersInputTopic,
  49                         String rankingInputTopic,
  50                         ObjectMapper mapper)
  51         {
  52                 StreamsBuilder builder = new StreamsBuilder();
  53
  54                 KTable<String, String> users = builder.table(usersInputTopic);
  55                 KStream<String, String> rankings = builder.stream(rankingInputTopic);
  56
  57                 rankings
  58                                 .join(users, (rankingJson, userJson) ->
  59                                 {
  60                                         try
  61                                         {
  62                                                 Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
  63                                                 User user = mapper.readValue(userJson, User.class);
  64
  65                                                 return mapper.writeValueAsString(
  66                                                                 UserRanking.of(
  67                                                                                 user.getFirstName(),
  68                                                                                 user.getLastName(),
  69                                                                                 ranking.getEntries()));
  70                                         }
  71                                         catch (JsonProcessingException e)
  72                                         {
  73                                                 throw new RuntimeException(e);
  74                                         }
  75                                 })
  76                                 .toTable(Materialized.as(STORE_NAME));
  77
  78                 Topology topology = builder.build();
  79                 log.info("\n\n{}", topology.describe());
  80
  81                 return topology;
  82         }
  83
  84         public Optional<URI> getRedirect(String username)
  85         {
  86                 KeyQueryMetadata metadata = streams.queryMetadataForKey(STORE_NAME, username, Serdes.String().serializer());
  87                 HostInfo activeHost = metadata.activeHost();
  88                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
  89
  90                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
  91                 {
  92                         return Optional.empty();
  93                 }
  94
  95                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
  96                 log.debug("Redirecting to {}", location);
  97                 return Optional.of(location);
  98         }
  99
 100         public Optional<UserRanking> getUserRanking(String username)
 101         {
 102                 return
 103                                 Optional
 104                                                 .ofNullable(streams.store(storeParameters).get(username))
 105                                                 .map(json ->
 106                                                 {
 107                                                         try
 108                                                         {
 109                                                                 return mapper.readValue(json, UserRanking.class);
 110                                                         }
 111                                                         catch (JsonProcessingException e)
 112                                                         {
 113                                                                 throw new RuntimeException(e);
 114                                                         }
 115                                                 });
 116         }
 117
 118         @PostConstruct
 119         public void start()
 120         {
 121                 log.info("Starting Stream-Processor");
 122                 streams.start();
 123         }
 124
 125         @PreDestroy
 126         public void stop()
 127         {
 128                 log.info("Stopping Stream-Processor");
 129                 streams.close();
 130         }
 131 }