package de.juplo.kafka.wordcount.counter;
-import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
-import org.apache.kafka.common.serialization.Serdes;
-import org.apache.kafka.streams.KafkaStreams;
-import org.apache.kafka.streams.KeyValue;
-import org.apache.kafka.streams.StreamsBuilder;
-import org.apache.kafka.streams.Topology;
-import org.apache.kafka.streams.kstream.KStream;
+import org.apache.kafka.streams.*;
+import org.apache.kafka.streams.kstream.Consumed;
import org.apache.kafka.streams.kstream.Materialized;
+import org.apache.kafka.streams.kstream.Produced;
import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
-import org.apache.kafka.streams.kstream.*;
+import org.apache.kafka.streams.state.QueryableStoreTypes;
+import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
import org.springframework.kafka.support.serializer.JsonSerde;
+import org.springframework.kafka.support.serializer.JsonSerializer;
+import java.util.Map;
import java.util.Properties;
+import java.util.stream.Collectors;
@Slf4j
public class CounterStreamProcessor
{
+ public static final String STORE_NAME = "counter";
+
+
public final KafkaStreams streams;
String inputTopic,
String outputTopic,
Properties properties,
- KeyValueBytesStoreSupplier storeSupplier,
- ObjectMapper mapper)
+ KeyValueBytesStoreSupplier storeSupplier)
{
Topology topology = CounterStreamProcessor.buildTopology(
inputTopic,
outputTopic,
- storeSupplier,
- mapper);
+ storeSupplier);
streams = new KafkaStreams(topology, properties);
}
static Topology buildTopology(
String inputTopic,
String outputTopic,
- KeyValueBytesStoreSupplier storeSupplier,
- ObjectMapper mapper)
+ KeyValueBytesStoreSupplier storeSupplier)
{
StreamsBuilder builder = new StreamsBuilder();
- KStream<String, Word> source = builder.stream(
- inputTopic,
- Consumed.with(
- Serdes.String(),
- new JsonSerde<>(Word.class)
- .ignoreTypeHeaders()));
-
- source
+ builder
+ .stream(inputTopic, Consumed.with(inKeySerde(), inValueSerde()))
.map((key, word) -> new KeyValue<>(word, word))
- .groupByKey(Grouped.with(
- new JsonSerde<>(Word.class)
- .forKeys()
- .noTypeInfo(),
- new JsonSerde<>(Word.class)
- .noTypeInfo()))
- .count(Materialized
- .<Word,Long>as(storeSupplier)
- .withKeySerde(
- new JsonSerde<>(Word.class)
- .forKeys()
- .noTypeInfo())
- .withValueSerde(
- Serdes.Long()))
+ .groupByKey()
+ .count(
+ Materialized
+ .<Word, Long>as(storeSupplier)
+ .withKeySerde(new JsonSerde<>(Word.class))) // No headers are present: fixed typing is needed!
.toStream()
- .map((word, count) -> new KeyValue<>(word, WordCount.of(word.getUser(), word.getWord(), count)))
- .to(
- outputTopic,
- Produced.with(
- new JsonSerde<>(Word.class)
- .forKeys()
- .noTypeInfo(),
- new JsonSerde<>(WordCount.class)
- .noTypeInfo()));
+ .map((word, counter) -> new KeyValue<>(word, WordCounter.of(word, counter)))
+ .to(outputTopic, Produced.with(outKeySerde(), outValueSerde()));
Topology topology = builder.build();
log.info("\n\n{}", topology.describe());
return topology;
}
+ ReadOnlyKeyValueStore<Word, Long> getStore()
+ {
+ return streams.store(StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore()));
+ }
+
public void start()
{
log.info("Starting Stream-Processor");
log.info("Stopping Stream-Processor");
streams.close();
}
+
+
+
+ public static JsonSerde<User> inKeySerde()
+ {
+ return new JsonSerde<>(User.class);
+ }
+
+ public static JsonSerde<Word> inValueSerde()
+ {
+ return new JsonSerde<>(Word.class);
+ }
+
+ public static JsonSerde<Word> outKeySerde()
+ {
+ return serde(true);
+ }
+
+ public static JsonSerde<WordCounter> outValueSerde()
+ {
+ return serde(false);
+ }
+
+ public static <T> JsonSerde<T> serde(boolean isKey)
+ {
+ JsonSerde<T> serde = new JsonSerde<>();
+ serde.configure(
+ Map.of(JsonSerializer.TYPE_MAPPINGS, typeMappingsConfig()),
+ isKey);
+ return serde;
+ }
+
+ private static String typeMappingsConfig()
+ {
+ return typeMappingsConfig(Word.class, WordCounter.class);
+ }
+
+ public static String typeMappingsConfig(Class wordClass, Class wordCounterClass)
+ {
+ return Map.of(
+ "word", wordClass,
+ "counter", wordCounterClass)
+ .entrySet()
+ .stream()
+ .map(entry -> entry.getKey() + ":" + entry.getValue().getName())
+ .collect(Collectors.joining(","));
+ }
}