1 package de.juplo.kafka.wordcount.query;
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;
21 import java.util.Optional;
22 import java.util.Properties;
26 public class QueryStreamProcessor
28 public final KafkaStreams streams;
29 public final HostInfo hostInfo;
30 public final String storeName = "rankingsByUsername";
31 public final StoreQueryParameters<ReadOnlyKeyValueStore<String, String>> storeParameters;
32 public final ObjectMapper mapper;
35 public QueryStreamProcessor(
37 HostInfo applicationServer,
38 String usersInputTopic,
39 String rankingInputTopic,
42 StreamsBuilder builder = new StreamsBuilder();
44 KTable<String, String> users = builder.table(usersInputTopic);
45 KStream<String, String> rankings = builder.stream(rankingInputTopic);
48 .join(users, (rankingJson, userJson) ->
52 Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
53 User user = mapper.readValue(userJson, User.class);
55 return mapper.writeValueAsString(
59 ranking.getEntries()));
61 catch (JsonProcessingException e)
63 throw new RuntimeException(e);
66 .toTable(Materialized.as(storeName));
68 streams = new KafkaStreams(builder.build(), props);
69 hostInfo = applicationServer;
70 storeParameters = StoreQueryParameters.fromNameAndType(storeName, QueryableStoreTypes.keyValueStore());;
74 public Optional<URI> getRedirect(String username)
76 KeyQueryMetadata metadata = streams.queryMetadataForKey(storeName, username, Serdes.String().serializer());
77 HostInfo activeHost = metadata.activeHost();
78 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
80 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
82 return Optional.empty();
85 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
86 log.debug("Redirecting to {}", location);
87 return Optional.of(location);
90 public Optional<UserRanking> getUserRanking(String username)
94 .ofNullable(streams.store(storeParameters).get(username))
99 return mapper.readValue(json, UserRanking.class);
101 catch (JsonProcessingException e)
103 throw new RuntimeException(e);
111 log.info("Starting Stream-Processor");
118 log.info("Stopping Stream-Processor");