/** * 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; import java.io.Serializable; import java.util.UUID; import org.apache.storm.Config; import org.apache.storm.topology.ConfigurableTopology; import org.apache.storm.topology.TopologyBuilder; import org.apache.storm.tuple.Values; public class LambdaTopology extends ConfigurableTopology { public static void main(String[] args) { ConfigurableTopology.start(new LambdaTopology(), args); } @Override protected int run(String[] args) throws Exception { TopologyBuilder builder = new TopologyBuilder(); // example. spout1: generate random strings // bolt1: get the first part of a string // bolt2: output the tuple // NOTE: Variable used in lambda expression should be final or effectively final // (or it will cause compilation error), // and variable type should implement the Serializable interface if it isn't primitive type // (or it will cause not serializable exception). Prefix prefix = new Prefix("Hello lambda:"); String suffix = ":so cool!"; int tag = 999; builder.setSpout("spout1", () -> UUID.randomUUID().toString()); builder.setBolt("bolt1", (tuple, collector) -> { String[] parts = tuple.getStringByField("lambda").split("\\-"); collector.emit(new Values(prefix + parts[0] + suffix, tag)); }, "strValue", "intValue").shuffleGrouping("spout1"); builder.setBolt("bolt2", tuple -> System.out.println(tuple)).shuffleGrouping("bolt1"); Config conf = new Config(); conf.setDebug(true); conf.setNumWorkers(2); return submit("lambda-demo", conf, builder); } } class Prefix implements Serializable { private String str; public Prefix(String str) { this.str = str; } @Override public String toString() { return this.str; } }