From 419be8ac0668ecb0e34b3a432cf2dcca1c3642dc Mon Sep 17 00:00:00 2001
From: Kai Moritz <kai@juplo.de>
Date: Sun, 16 Jun 2024 19:57:23 +0200
Subject: [PATCH] counter: 1.3.1 - Refined/Simplified the type-mapping

* Removed all explicit type-mappings for the internally used types.
* This greatly simplifies the configuration, because it is sufficient to
  configure the trusted package to serialize/deserialize all internally
  used types.
* To make this possible, the type-mappings for the outgoing messages are
  specified with `Produced.with()` in the ``to()``-operation.
---
 .../CounterApplicationConfiguriation.java     |  6 +--
 .../counter/CounterStreamProcessor.java       | 43 ++++++++++++++++++-
 2 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/src/main/java/de/juplo/kafka/wordcount/counter/CounterApplicationConfiguriation.java b/src/main/java/de/juplo/kafka/wordcount/counter/CounterApplicationConfiguriation.java
index d9579a5..174521f 100644
--- a/src/main/java/de/juplo/kafka/wordcount/counter/CounterApplicationConfiguriation.java
+++ b/src/main/java/de/juplo/kafka/wordcount/counter/CounterApplicationConfiguriation.java
@@ -50,11 +50,7 @@ public class CounterApplicationConfiguriation
 
 		propertyMap.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, JsonSerde.class.getName());
 		propertyMap.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, JsonSerde.class.getName());
-		propertyMap.put(
-				JsonDeserializer.TYPE_MAPPINGS,
-				"user:" + User.class.getName() + "," +
-				"word:" + Word.class.getName() + "," +
-				"counter:" + WordCounter.class.getName());
+		propertyMap.put(JsonDeserializer.TRUSTED_PACKAGES, CounterApplication.class.getPackageName());
 
 		return propertyMap;
 	}
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 8b9c12b..97d460f 100644
--- a/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java
+++ b/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java
@@ -4,12 +4,16 @@ import lombok.extern.slf4j.Slf4j;
 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.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
@@ -56,7 +60,7 @@ public class CounterStreamProcessor
 								.withKeySerde(new JsonSerde<>().copyWithType(Word.class).forKeys()))
 				.toStream()
 				.map((word, counter) -> new KeyValue<>(word, WordCounter.of(word, counter)))
-				.to(outputTopic);
+				.to(outputTopic, Produced.with(outKeySerde(), outValueSerde()));
 
 		Topology topology = builder.build();
 		log.info("\n\n{}", topology.describe());
@@ -80,4 +84,41 @@ public class CounterStreamProcessor
 		log.info("Stopping Stream-Processor");
 		streams.close();
 	}
+
+
+
+	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 typeMappings()
+				.entrySet()
+				.stream()
+				.map(entry -> entry.getKey() + ":" + entry.getValue().getName())
+				.collect(Collectors.joining(","));
+	}
+
+	private static Map<String, Class> typeMappings()
+	{
+		return Map.of(
+				"word", Word.class,
+				"counter", WordCounter.class);
+	}
 }
-- 
2.20.1