Calculate average brake temperature

brake-temperature/src/main/java/com/springone/braketemperature/BrakeTemperatureApplication.java

@@ -5,11 +5,14 @@
 import org.apache.kafka.streams.kstream.Grouped;
 import org.apache.kafka.streams.kstream.KStream;
 import org.apache.kafka.streams.kstream.Materialized;
+import org.apache.kafka.streams.kstream.TimeWindows;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.context.annotation.Bean;
 import org.springframework.kafka.support.serializer.JsonSerde;
 
+import java.time.Duration;
+import java.util.Date;
 import java.util.function.Function;
 
 @SpringBootApplication
@@ -20,24 +23,41 @@ public static void main(String[] args) {
 	}
 
 	@Bean
-	public Function<KStream<Object, Truck>, KStream<String, Long>> process() {
+	public Function<KStream<Object, Truck>, KStream<String, AverageBrakeTemperatureAccumulator>> processBrakeTemperature() {
 
 		return input -> input
-				.map((k, v) -> new KeyValue<>(((Truck) v).getId(), v))
+				.map((k, v) -> new KeyValue<>(v.getId(), v))
 				.groupByKey(Grouped.with(Serdes.String(), new JsonSerde<>(Truck.class)))
-				//				.windowedBy(TimeWindows.of(10000))
-				.count(Materialized.as("foo"))
-				.toStream();
-
+				.windowedBy(TimeWindows.of(Duration.ofSeconds(10)))
+				.aggregate(() -> new AverageBrakeTemperatureAccumulator(0, 0F),
+						(k, v, agg) -> {
+							agg.setCount(agg.getCount() + 1);
+							agg.setTotalValue(v.getBrakeTemperature());
+							agg.setAverage(agg.getTotalValue() / agg.getCount());
+							return agg;
+						},
+						Materialized.with(Serdes.String(), new JsonSerde<>(AverageBrakeTemperatureAccumulator.class)))
+				.toStream()
+				.map((k, v) -> {
+					v.setStart(new Date(k.window().start()));
+					v.setEnd(new Date(k.window().end()));
+					return new KeyValue<>(k.key(), v);
+				});
 	}
 
-	class Accumulator {
+	class AverageBrakeTemperatureAccumulator {
 
 		private int count;
 
-		private int totalValue;
+		private Float totalValue;
+
+		private double average;
+
+		private Date start;
+
+		private Date end;
 
-		public Accumulator(int count, int totalValue) {
+		public AverageBrakeTemperatureAccumulator(int count, Float totalValue) {
 			this.count = count;
 			this.totalValue = totalValue;
 		}
@@ -50,12 +70,36 @@ public void setCount(int count) {
 			this.count = count;
 		}
 
-		public int getTotalValue() {
+		public Float getTotalValue() {
 			return totalValue;
 		}
 
-		public void setTotalValue(int totalValue) {
+		public void setTotalValue(Float totalValue) {
 			this.totalValue = totalValue;
 		}
+
+		public double getAverage() {
+			return average;
+		}
+
+		public void setAverage(double average) {
+			this.average = average;
+		}
+
+		public Date getStart() {
+			return start;
+		}
+
+		public void setStart(Date start) {
+			this.start = start;
+		}
+
+		public Date getEnd() {
+			return end;
+		}
+
+		public void setEnd(Date end) {
+			this.end = end;
+		}
 	}
 }

trucks/src/main/java/com/springone/trucks/TrucksApplication.java

@@ -33,11 +33,11 @@ public static void main(String[] args) {
 
 	@Bean
 	@Scheduled(fixedRate = 1000L)
-	public Supplier<Truck> supplier() {
-		return () -> randomCar();
+	public Supplier<Truck> generateTruck() {
+		return () -> randomTruck();
 	}
 
-	private Truck randomCar() {
+	private Truck randomTruck() {
 		Truck truck = new Truck();
 		truck.setId(VIN_LIST.get(random.nextInt(VIN_LIST.size())));
 		truck.setAcceleration(random.nextFloat() * 10);