WordCounter.java

/*
 * Copyright © 2014 Cask Data, Inc.
 *
 * Licensed 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 co.cask.cdap.examples.wordcount;


import co.cask.cdap.api.flow.AbstractFlow;

/**
 * Flow that takes any arbitrary string of input and performs word statistics.
 * <p>
 * Flow parses input string into individual words, then performs per-word counts
 * and other calculations like total number of words seen, average length
 * of words seen, unique words seen, and also tracks the words most often
 * associated with each other word.
 * <p>
 * The first Flowlet is the WordSplitter, which splits the sentence into
 * individual words, cleans up non-alpha characters, and then sends the
 * sentences to the WordAssociater and the words on to the WordCounter.
 * <p>
 * The next Flowlet is the WordAssociater that will track word associations
 * between all of the words within the input string.
 * <p>
 * The next Flowlet is the Counter, which performs the necessary data
 * operations to do the word count and count other word statistics.
 * <p>
 * The last Flowlet is the UniqueCounter, which calculates and updates the
 * unique number of words seen.
 */
public class WordCounter extends AbstractFlow {

  private final WordCount.WordCountConfig config;

  public WordCounter(WordCount.WordCountConfig config) {
    this.config = config;
  }

  @Override
  protected void configure() {
    setName("WordCounter");
    setDescription("Example Word Count Flow");
    addFlowlet("splitter", new WordSplitter(config.getWordStatsTable()));
    addFlowlet("associator", new WordAssociator(config.getWordAssocTable()));
    addFlowlet("counter", new Counter(config.getWordCountTable()));
    addFlowlet("unique", new UniqueCounter(config.getUniqueCountTable()));
    connectStream(config.getStream(), "splitter");
    connect("splitter", "associator");
    connect("splitter", "counter");
    connect("counter", "unique");
  }
}