/* * 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 com.dataartisans; import org.apache.flink.api.common.functions.MapFunction; import org.apache.flink.api.java.utils.ParameterTool; import org.apache.flink.streaming.api.datastream.DataStream; import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment; import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer082; import org.apache.flink.streaming.util.serialization.SimpleStringSchema; /** * Simple example on how to read with a Kafka consumer * * Note that the Kafka source is expecting the following parameters to be set * - "bootstrap.servers" (comma separated list of kafka brokers) * - "zookeeper.connect" (comma separated list of zookeeper servers) * - "group.id" the id of the consumer group * - "topic" the name of the topic to read data from. * * You can pass these required parameters using "--bootstrap.servers host:port,host1:port1 --zookeeper.connect host:port --topic testTopic" * * This is a valid input example: * --topic test --bootstrap.servers localhost:9092 --zookeeper.connect localhost:2181 --group.id myGroup * * */ public class ReadFromKafka { public static void main(String[] args) throws Exception { // create execution environment StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); // parse user parameters ParameterTool parameterTool = ParameterTool.fromArgs(args); DataStream<String> messageStream = env.addSource(new FlinkKafkaConsumer082<>(parameterTool.getRequired("topic"), new SimpleStringSchema(), parameterTool.getProperties())); // print() will write the contents of the stream to the TaskManager's standard out stream // the rebelance call is causing a repartitioning of the data so that all machines // see the messages (for example in cases when "num kafka partitions" < "num flink operators" messageStream.rebalance().map(new MapFunction<String, String>() { private static final long serialVersionUID = -6867736771747690202L; @Override public String map(String value) throws Exception { return "Kafka and Flink says: " + value; } }).print(); env.execute(); } }