Adding new sample for multibinder kafka streams

multibinder-samples/multibinder-kafka-streams/src/main/java/multibinder/BridgeTransformer.java

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+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package multibinder;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.kafka.common.serialization.Serde;
+import org.apache.kafka.common.serialization.Serdes;
+import org.apache.kafka.common.utils.Bytes;
+import org.apache.kafka.streams.kstream.ForeachAction;
+import org.apache.kafka.streams.kstream.KStream;
+import org.apache.kafka.streams.kstream.Materialized;
+import org.apache.kafka.streams.kstream.Serialized;
+import org.apache.kafka.streams.state.KeyValueStore;
+import org.apache.kafka.streams.state.QueryableStoreTypes;
+import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.cloud.stream.annotation.EnableBinding;
+import org.springframework.cloud.stream.annotation.Input;
+import org.springframework.cloud.stream.annotation.Output;
+import org.springframework.cloud.stream.annotation.StreamListener;
+import org.springframework.cloud.stream.binder.kafka.streams.InteractiveQueryService;
+import org.springframework.cloud.stream.messaging.Processor;
+import org.springframework.context.annotation.Bean;
+import org.springframework.integration.annotation.InboundChannelAdapter;
+import org.springframework.integration.annotation.Poller;
+import org.springframework.integration.core.MessageSource;
+import org.springframework.kafka.support.serializer.JsonSerde;
+import org.springframework.messaging.MessageChannel;
+import org.springframework.messaging.SubscribableChannel;
+import org.springframework.messaging.handler.annotation.SendTo;
+import org.springframework.messaging.support.GenericMessage;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * @author Marius Bogoevici
+ * @author Soby Chacko
+ */
+@EnableBinding(Processor.class)
+public class BridgeTransformer {
+
+	@Autowired
+	private InteractiveQueryService interactiveQueryService;
+
+	@StreamListener(Processor.INPUT)
+	@SendTo(Processor.OUTPUT)
+	public Object transform(Object payload) {
+		return payload;
+	}
+
+	//Following source is used as test producer.
+	@EnableBinding(TestSource.class)
+	static class TestProducer {
+
+		private AtomicBoolean semaphore = new AtomicBoolean(true);
+
+		@Bean
+		@InboundChannelAdapter(channel = TestSource.OUTPUT, poller = @Poller(fixedDelay = "1000"))
+		public MessageSource<String> sendTestData() {
+			return () ->
+					new GenericMessage<>(this.semaphore.getAndSet(!this.semaphore.get()) ? "foo" : "bar");
+
+		}
+	}
+
+	//Following sink is used as test consumer for the above processor. It logs the data received through the processor.
+	@EnableBinding(TestSink.class)
+	static class TestConsumer {
+
+		private final Log logger = LogFactory.getLog(getClass());
+
+		@StreamListener(TestSink.INPUT)
+		public void receive(String data) {
+			logger.info("Data received..." + data);
+		}
+	}
+
+	@EnableBinding(KafkaStreamsProcessorX.class)
+	static class KafkaStreamsAggregateSampleApplication {
+
+		@StreamListener("input2")
+		public void process(KStream<Object, DomainEvent> input) {
+			ObjectMapper mapper = new ObjectMapper();
+			Serde<DomainEvent> domainEventSerde = new JsonSerde<>( DomainEvent.class, mapper );
+
+			input
+					.groupBy(
+							(s, domainEvent) -> domainEvent.boardUuid,
+							Serialized.with(null, domainEventSerde))
+					.aggregate(
+							String::new,
+							(s, domainEvent, board) -> board.concat(domainEvent.eventType),
+							Materialized.<String, String, KeyValueStore<Bytes, byte[]>>as("test-events-snapshots").withKeySerde(Serdes.String()).
+									withValueSerde(Serdes.String())
+					);
+		}
+	}
+
+	@RestController
+	public class FooController {
+
+		@RequestMapping("/events")
+		public String events() {
+
+			final ReadOnlyKeyValueStore<String, String> topFiveStore =
+					interactiveQueryService.getQueryableStore("test-events-snapshots", QueryableStoreTypes.<String, String>keyValueStore());
+			return topFiveStore.get("12345");
+		}
+	}
+
+	interface TestSink {
+
+		String INPUT = "input1";
+
+		@Input(INPUT)
+		SubscribableChannel input1();
+
+	}
+
+	interface TestSource {
+
+		String OUTPUT = "output1";
+
+		@Output(TestSource.OUTPUT)
+		MessageChannel output();
+
+	}
+
+	interface KafkaStreamsProcessorX {
+
+		@Input("input2")
+		KStream<?, ?> input2();
+	}
+
+}