coutner: 1.2.3 - Simplified topology, using default-serdes for all steps

[demos/kafka/wordcount] / src / main / java / de / juplo / kafka / wordcount / counter / CounterStreamProcessor.java

diff --git a/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java b/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java
index b19502d..d64eb68 100644 (file)
--- a/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java
+++ b/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java
@@ -1,14 +1,15 @@
 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.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.kstream.Materialized;
 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
+import org.apache.kafka.streams.kstream.*;
 
 import java.util.Properties;
 
@@ -25,30 +26,40 @@ public class CounterStreamProcessor
                        Properties properties,
                        KeyValueBytesStoreSupplier storeSupplier,
                        ObjectMapper mapper)
+       {
+               Topology topology = CounterStreamProcessor.buildTopology(
+                               inputTopic,
+                               outputTopic,
+                               storeSupplier,
+                               mapper);
+
+               streams = new KafkaStreams(topology, properties);
+       }
+
+       static Topology buildTopology(
+                       String inputTopic,
+                       String outputTopic,
+                       KeyValueBytesStoreSupplier storeSupplier,
+                       ObjectMapper mapper)
        {
                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(Materialized.as(storeSupplier))
-                               .mapValues(value->Long.toString(value))
                                .toStream()
+                               .map((word, count) -> new KeyValue<>(word, WordCount.of(word, count)))
                                .to(outputTopic);
 
-               streams = new KafkaStreams(builder.build(), properties);
+               Topology topology = builder.build();
+               log.info("\n\n{}", topology.describe());
+
+               return topology;
        }
 
        public void start()