StreamsJoinWithRepartitioning.java

/*
 * 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.
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package org.apache.kafka.streams;

import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.streams.kstream.JoinWindows;
import org.apache.kafka.streams.kstream.KStream;

import java.time.Duration;
import java.util.Properties;

public class StreamsJoinWithRepartitioning {

    public static void main(String[] args) {
        final Properties properties = new Properties();
        properties.setProperty(StreamsConfig.APPLICATION_ID_CONFIG, "test-application");
        properties.setProperty(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
        properties.setProperty(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
        properties.setProperty(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());

        final StreamsBuilder builder = new StreamsBuilder();


        final KStream<String, String> streamOne = builder.stream("input-topic-one");
        final KStream<String, String> streamTwo = builder.stream("input-topic-two");

        final KStream<String, String> streamOneNewKey = streamOne.selectKey((k, v) -> v.substring(0, 5));
        final KStream<String, String> streamTwoNewKey = streamTwo.selectKey((k, v) -> v.substring(4, 9));


        streamOneNewKey.join(streamTwoNewKey,(v1, v2) -> v1+":"+v2, JoinWindows.of(Duration.ofMinutes(5))).to("joined-output");


        final Topology topology = builder.build(properties);
        // Could also be done via a log statement
        System.out.println(topology.describe());

        final KafkaStreams kafkaStreams = new KafkaStreams(topology, properties);

        kafkaStreams.start();
    }
}