package de.juplo.kafka.wordcount.query;
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.ObjectMapper;
import jakarta.annotation.PostConstruct;
import jakarta.annotation.PreDestroy;
import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.common.serialization.Serdes;
-import org.apache.kafka.streams.KafkaStreams;
-import org.apache.kafka.streams.KeyQueryMetadata;
-import org.apache.kafka.streams.StoreQueryParameters;
-import org.apache.kafka.streams.StreamsBuilder;
+import org.apache.kafka.streams.*;
import org.apache.kafka.streams.kstream.KStream;
import org.apache.kafka.streams.kstream.KTable;
import org.apache.kafka.streams.kstream.Materialized;
import org.apache.kafka.streams.state.HostInfo;
+import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
import org.apache.kafka.streams.state.QueryableStoreTypes;
import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
-import org.springframework.boot.SpringApplication;
-import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.kafka.support.serializer.JsonSerde;
import java.net.URI;
import java.util.Optional;
import java.util.Properties;
-import java.util.concurrent.CompletableFuture;
-
-import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
@Slf4j
public class QueryStreamProcessor
{
+ public static final String USER_STORE_NAME = "users";
+ public static final String RANKING_STORE_NAME = "rankings";
+
public final KafkaStreams streams;
public final HostInfo hostInfo;
- public final String storeName = "rankingsByUsername";
- public final StoreQueryParameters<ReadOnlyKeyValueStore<String, String>> storeParameters;
- public final ObjectMapper mapper;
+ public final StoreQueryParameters<ReadOnlyKeyValueStore<String, UserRanking>> storeParameters;
public QueryStreamProcessor(
HostInfo applicationServer,
String usersInputTopic,
String rankingInputTopic,
- ObjectMapper mapper,
- ConfigurableApplicationContext context)
+ KeyValueBytesStoreSupplier userStoreSupplier,
+ KeyValueBytesStoreSupplier rankingStoreSupplier)
+ {
+ Topology topology = buildTopology(
+ usersInputTopic,
+ rankingInputTopic,
+ userStoreSupplier,
+ rankingStoreSupplier);
+ streams = new KafkaStreams(topology, props);
+ hostInfo = applicationServer;
+ storeParameters = StoreQueryParameters.fromNameAndType(RANKING_STORE_NAME, QueryableStoreTypes.keyValueStore());;
+ }
+
+ static Topology buildTopology(
+ String usersInputTopic,
+ String rankingInputTopic,
+ KeyValueBytesStoreSupplier userStoreSupplier,
+ KeyValueBytesStoreSupplier rankingStoreSupplier)
{
StreamsBuilder builder = new StreamsBuilder();
- KTable<String, String> users = builder.table(usersInputTopic);
- KStream<String, String> rankings = builder.stream(rankingInputTopic);
+ KTable<String, User> users = builder
+ .stream(usersInputTopic)
+ .toTable(
+ Materialized
+ .<String, User>as(userStoreSupplier)
+ .withKeySerde(Serdes.String())
+ .withValueSerde(new JsonSerde().copyWithType(User.class)));
+ KStream<String, Ranking> rankings = builder.stream(rankingInputTopic);
rankings
- .join(users, (rankingJson, userJson) ->
- {
- try
- {
- Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
- User user = mapper.readValue(userJson, User.class);
-
- return mapper.writeValueAsString(
- UserRanking.of(
- user.getFirstName(),
- user.getLastName(),
- ranking.getEntries()));
- }
- catch (JsonProcessingException e)
- {
- throw new RuntimeException(e);
- }
- })
- .toTable(Materialized.as(storeName));
-
- streams = new KafkaStreams(builder.build(), props);
- streams.setUncaughtExceptionHandler((Throwable e) ->
- {
- log.error("Unexpected error!", e);
- CompletableFuture.runAsync(() ->
- {
- log.info("Stopping application...");
- SpringApplication.exit(context, () -> 1);
- });
- return SHUTDOWN_CLIENT;
- });
+ .join(users, (ranking, user) -> UserRanking.of(
+ user.getFirstName(),
+ user.getLastName(),
+ ranking.getEntries()))
+ .toTable(
+ Materialized
+ .<String, UserRanking>as(rankingStoreSupplier)
+ .withValueSerde(new JsonSerde().copyWithType(UserRanking.class)));
+
+ Topology topology = builder.build();
+ log.info("\n\n{}", topology.describe());
+
+ return topology;
+ }
- hostInfo = applicationServer;
- storeParameters = StoreQueryParameters.fromNameAndType(storeName, QueryableStoreTypes.keyValueStore());;
- this.mapper = mapper;
+ ReadOnlyKeyValueStore<String, UserRanking> getStore()
+ {
+ return streams.store(storeParameters);
}
public Optional<URI> getRedirect(String username)
{
- KeyQueryMetadata metadata = streams.queryMetadataForKey(storeName, username, Serdes.String().serializer());
+ KeyQueryMetadata metadata = streams.queryMetadataForKey(RANKING_STORE_NAME, username, Serdes.String().serializer());
HostInfo activeHost = metadata.activeHost();
log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
public Optional<UserRanking> getUserRanking(String username)
{
- return
- Optional
- .ofNullable(streams.store(storeParameters).get(username))
- .map(json ->
- {
- try
- {
- return mapper.readValue(json, UserRanking.class);
- }
- catch (JsonProcessingException e)
- {
- throw new RuntimeException(e);
- }
- });
+ return Optional.ofNullable(getStore().get(username));
}
@PostConstruct
projects / demos / kafka / wordcount / blobdiff