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TumblingPageViewCounterApp.java
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TumblingPageViewCounterApp.java
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 samza.examples.cookbook;
import org.apache.samza.application.StreamApplication;
import org.apache.samza.config.Config;
import org.apache.samza.operators.KV;
import org.apache.samza.operators.MessageStream;
import org.apache.samza.operators.OutputStream;
import org.apache.samza.operators.StreamGraph;
import org.apache.samza.operators.windows.Windows;
import org.apache.samza.serializers.JsonSerdeV2;
import org.apache.samza.serializers.KVSerde;
import org.apache.samza.serializers.StringSerde;
import samza.examples.cookbook.data.PageView;
import samza.examples.cookbook.data.UserPageViews;
import java.time.Duration;
/**
* In this example, we group a stream of page views by country, and compute the number of page views over a tumbling time
* window.
*
* <p> Concepts covered: Performing Group-By style aggregations on tumbling time windows.
*
* <p> Tumbling windows divide a stream into a set of contiguous, fixed-sized, non-overlapping time intervals.
*
* To run the below example:
*
* <ol>
* <li>
* Ensure that the topic "pageview-tumbling-input" is created <br/>
* ./deploy/kafka/bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic pageview-tumbling-input --partitions 2 --replication-factor 1
* </li>
* <li>
* Run the application using the run-app.sh script <br/>
* ./deploy/samza/bin/run-app.sh --config-factory=org.apache.samza.config.factories.PropertiesConfigFactory --config-path=file://$PWD/deploy/samza/config/tumbling-pageview-counter.properties
* </li>
* <li>
* Produce some messages to the "pageview-tumbling-input" topic, waiting for some time between messages <br/>
./deploy/kafka/bin/kafka-console-producer.sh --topic pageview-tumbling-input --broker-list localhost:9092 <br/>
* {"userId": "user1", "country": "india", "pageId":"google.com/home"} <br/>
* {"userId": "user1", "country": "india", "pageId":"google.com/search"} <br/>
* {"userId": "user2", "country": "china", "pageId":"yahoo.com/home"} <br/>
* {"userId": "user2", "country": "china", "pageId":"yahoo.com/sports"} <br/>
* {"userId": "user1", "country": "india", "pageId":"google.com/news"} <br/>
* {"userId": "user2", "country": "china", "pageId":"yahoo.com/fashion"}
* </li>
* <li>
* Consume messages from the "pageview-tumbling-output" topic (e.g. bin/kafka-console-consumer.sh)
* ./deploy/kafka/bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic pageview-tumbling-output --property print.key=true <br/>
* </li>
* </ol>
*
*/
public class TumblingPageViewCounterApp implements StreamApplication {
private static final String INPUT_TOPIC = "pageview-tumbling-input";
private static final String OUTPUT_TOPIC = "pageview-tumbling-output";
@Override
public void init(StreamGraph graph, Config config) {
graph.setDefaultSerde(KVSerde.of(new StringSerde(), new JsonSerdeV2<>(PageView.class)));
MessageStream<KV<String, PageView>> pageViews = graph.getInputStream(INPUT_TOPIC);
OutputStream<KV<String, UserPageViews>> outputStream =
graph.getOutputStream(OUTPUT_TOPIC, KVSerde.of(new StringSerde(), new JsonSerdeV2<>(UserPageViews.class)));
pageViews
.partitionBy(kv -> kv.value.userId, kv -> kv.value)
.window(Windows.keyedTumblingWindow(
kv -> kv.key, Duration.ofSeconds(5), () -> 0, (m, prevCount) -> prevCount + 1))
.map(windowPane -> {
String userId = windowPane.getKey().getKey();
int views = windowPane.getMessage();
return KV.of(userId, new UserPageViews(userId, views));
})
.sendTo(outputStream);
}
}