WordCount with data from a text socket via apache flink - Java Big Data

Java examples for Big Data:apache flink

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Description

WordCount with data from a text socket via apache flink

Demo Code


/*//from  ww w . j  ava 2s. c o m
 * 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.
 */

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.util.Collector;

/**
 * This example shows an implementation of WordCount with data from a text
 * socket. To run the example make sure that the service providing the text data
 * is already up and running.
 * 
 * <p>
 * To start an example socket text stream on your local machine run netcat from
 * a command line: <code>nc -lk 9999</code>, where the parameter specifies the
 * port number.
 * 
 * 
 * <p>
 * Usage:
 * <code>SocketTextStreamWordCount &lt;hostname&gt; &lt;port&gt; &lt;result path&gt;</code>
 * <br>
 * 
 * <p>
 * This example shows how to:
 * <ul>
 * <li>use StreamExecutionEnvironment.socketTextStream
 * <li>write a simple Flink program,
 * <li>write and use user-defined functions.
 * </ul>
 * 
 * @see <a href="www.openbsd.org/cgi-bin/man.cgi?query=nc">netcat</a>
 */
public class SocketTextStreamWordCount {

    //
    //  Program
    //

    public static void main(String[] args) throws Exception {

        if (args.length != 2) {
            System.err
                    .println("USAGE:\nSocketTextStreamWordCount <hostname> <port>");
            return;
        }

        String hostName = args[0];
        Integer port = Integer.parseInt(args[1]);

        // set up the execution environment
        final StreamExecutionEnvironment env = StreamExecutionEnvironment
                .getExecutionEnvironment();

        // get input data
        DataStream<String> text = env.socketTextStream(hostName, port);

        DataStream<Tuple2<String, Integer>> counts =
        // split up the lines in pairs (2-tuples) containing: (word,1)
        text.flatMap(new LineSplitter())
        // group by the tuple field "0" and sum up tuple field "1"
                .keyBy(0).sum(1);

        counts.print();

        // execute program
        env.execute("WordCount from SocketTextStream Example");
    }

    //
    //   User Functions
    //

    /**
     * Implements the string tokenizer that splits sentences into words as a user-defined
     * FlatMapFunction. The function takes a line (String) and splits it into
     * multiple pairs in the form of "(word,1)" (Tuple2<String, Integer>).
     */
    public static final class LineSplitter implements
            FlatMapFunction<String, Tuple2<String, Integer>> {

        @Override
        public void flatMap(String value,
                Collector<Tuple2<String, Integer>> out) {
            // normalize and split the line
            String[] tokens = value.toLowerCase().split("\\W+");

            // emit the pairs
            for (String token : tokens) {
                if (token.length() > 0) {
                    out.collect(new Tuple2<String, Integer>(token, 1));
                }
            }
        }
    }
}

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