/** * 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 org.apache.storm.starter.streams; import org.apache.storm.Config; import org.apache.storm.StormSubmitter; import org.apache.storm.starter.spout.RandomIntegerSpout; import org.apache.storm.streams.Pair; import org.apache.storm.streams.StreamBuilder; import org.apache.storm.streams.operations.CombinerAggregator; import org.apache.storm.streams.operations.mappers.ValueMapper; import org.apache.storm.streams.windowing.TumblingWindows; import org.apache.storm.topology.base.BaseWindowedBolt; /** * An example that illustrates the global aggregate */ public class AggregateExample { @SuppressWarnings("unchecked") public static void main(String[] args) throws Exception { StreamBuilder builder = new StreamBuilder(); /** * Computes average of the stream of numbers emitted by the spout. Internally the per-partition * sum and counts are accumulated and emitted to a downstream task where the partially accumulated * results are merged and the final result is emitted. */ builder.newStream(new RandomIntegerSpout(), new ValueMapper<Integer>(0), 2) .window(TumblingWindows.of(BaseWindowedBolt.Duration.seconds(5))) .filter(x -> x > 0 && x < 500) .aggregate(new Avg()) .print(); Config config = new Config(); String topoName = "AGG_EXAMPLE"; if (args.length > 0) { topoName = args[0]; } config.setNumWorkers(1); StormSubmitter.submitTopologyWithProgressBar(topoName, config, builder.build()); } private static class Avg implements CombinerAggregator<Integer, Pair<Integer, Integer>, Double> { @Override public Pair<Integer, Integer> init() { return Pair.of(0, 0); } @Override public Pair<Integer, Integer> apply(Pair<Integer, Integer> sumAndCount, Integer value) { return Pair.of(sumAndCount._1 + value, sumAndCount._2 + 1); } @Override public Pair<Integer, Integer> merge(Pair<Integer, Integer> sumAndCount1, Pair<Integer, Integer> sumAndCount2) { System.out.println("Merge " + sumAndCount1 + " and " + sumAndCount2); return Pair.of( sumAndCount1._1 + sumAndCount2._1, sumAndCount1._2 + sumAndCount2._2 ); } @Override public Double result(Pair<Integer, Integer> sumAndCount) { return (double) sumAndCount._1 / sumAndCount._2; } } }