added the basic SocketWindowWordCount from flink examples

src/main/java/net/juliobiason/flink/SocketWindowWordCount.java

@@ -0,0 +1,117 @@
+/*
+ * 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 net.juliobiason.flink;
+
+import org.apache.flink.api.common.functions.FlatMapFunction;
+import org.apache.flink.api.common.functions.ReduceFunction;
+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.api.windowing.time.Time;
+import org.apache.flink.util.Collector;
+
+/**
+ * Implements a streaming windowed version of the "WordCount" program.
+ *
+ * <p>This program connects to a server socket and reads strings from the socket.
+ * The easiest way to try this out is to open a text server (at port 12345)
+ * using the <i>netcat</i> tool via
+ * <pre>
+ * nc -l 12345
+ * </pre>
+ * and run this example with the hostname and the port as arguments.
+ */
+@SuppressWarnings("serial")
+public class SocketWindowWordCount {
+
+	public static void main(String[] args) throws Exception {
+
+		// the host and the port to connect to
+		final String hostname;
+		final int port;
+		try {
+			final ParameterTool params = ParameterTool.fromArgs(args);
+			hostname = params.has("hostname") ? params.get("hostname") : "localhost";
+			port = params.getInt("port");
+		} catch (Exception e) {
+			System.err.println("No port specified. Please run 'SocketWindowWordCount " +
+				"--hostname <hostname> --port <port>', where hostname (localhost by default) " +
+				"and port is the address of the text server");
+			System.err.println("To start a simple text server, run 'netcat -l <port>' and " +
+				"type the input text into the command line");
+			return;
+		}
+
+		// get the execution environment
+		final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
+
+		// get input data by connecting to the socket
+		DataStream<String> text = env.socketTextStream(hostname, port, "\n");
+
+		// parse the data, group it, window it, and aggregate the counts
+		DataStream<WordWithCount> windowCounts = text
+
+				.flatMap(new FlatMapFunction<String, WordWithCount>() {
+					@Override
+					public void flatMap(String value, Collector<WordWithCount> out) {
+						for (String word : value.split("\\s")) {
+							out.collect(new WordWithCount(word, 1L));
+						}
+					}
+				})
+
+				.keyBy("word")
+				.timeWindow(Time.seconds(5))
+
+				.reduce(new ReduceFunction<WordWithCount>() {
+					@Override
+					public WordWithCount reduce(WordWithCount a, WordWithCount b) {
+						return new WordWithCount(a.word, a.count + b.count);
+					}
+				});
+
+		// print the results with a single thread, rather than in parallel
+		windowCounts.print().setParallelism(1);
+
+		env.execute("Socket Window WordCount");
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Data type for words with count.
+	 */
+	public static class WordWithCount {
+
+		public String word;
+		public long count;
+
+		public WordWithCount() {}
+
+		public WordWithCount(String word, long count) {
+			this.word = word;
+			this.count = count;
+		}
+
+		@Override
+		public String toString() {
+			return word + " : " + count;
+		}
+	}
+}