package de.juplo.kafka.wordcount.counter;
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
-import org.apache.kafka.streams.KafkaStreams;
-import org.apache.kafka.streams.KeyValue;
-import org.apache.kafka.streams.StreamsBuilder;
+import org.apache.kafka.common.serialization.Serdes;
+import org.apache.kafka.streams.*;
+import org.apache.kafka.streams.kstream.Consumed;
import org.apache.kafka.streams.kstream.KStream;
+import org.apache.kafka.streams.kstream.Materialized;
+import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
+import org.apache.kafka.streams.state.QueryableStoreTypes;
+import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
import java.util.Properties;
@Slf4j
public class CounterStreamProcessor
{
+ public static final String STORE_NAME = "counter";
+
+
public final KafkaStreams streams;
String inputTopic,
String outputTopic,
Properties properties,
- ObjectMapper mapper)
+ KeyValueBytesStoreSupplier storeSupplier)
+ {
+ Topology topology = CounterStreamProcessor.buildTopology(
+ inputTopic,
+ outputTopic,
+ storeSupplier);
+
+ streams = new KafkaStreams(topology, properties);
+ }
+
+ static Topology buildTopology(
+ String inputTopic,
+ String outputTopic,
+ KeyValueBytesStoreSupplier storeSupplier)
{
StreamsBuilder builder = new StreamsBuilder();
- KStream<String, String> source = builder.stream(inputTopic);
+ KStream<String, Word> source = builder.stream(
+ inputTopic,
+ Consumed.with(Serdes.String(), null));
+
source
- .map((username, word) ->
- {
- try
- {
- String key = mapper.writeValueAsString(Key.of(username, word));
- return new KeyValue<>(key, word);
- }
- catch (JsonProcessingException e)
- {
- throw new RuntimeException(e);
- }
- })
+ .map((key, word) -> new KeyValue<>(word, word))
.groupByKey()
- .count()
- .mapValues(value->Long.toString(value))
+ .count(Materialized.as(storeSupplier))
.toStream()
+ .map((word, counter) -> new KeyValue<>(word, WordCounter.of(word, counter)))
.to(outputTopic);
- streams = new KafkaStreams(builder.build(), properties);
+ 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()