Github user revans2 commented on a diff in the pull request:
https://github.com/apache/storm/pull/855#discussion_r43904817
--- Diff:
examples/storm-starter/src/jvm/storm/starter/SlidingWindowTopology.java ---
@@ -0,0 +1,129 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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 storm.starter;
+
+import backtype.storm.Config;
+import backtype.storm.LocalCluster;
+import backtype.storm.StormSubmitter;
+import backtype.storm.spout.SpoutOutputCollector;
+import backtype.storm.task.OutputCollector;
+import backtype.storm.task.TopologyContext;
+import backtype.storm.topology.OutputFieldsDeclarer;
+import backtype.storm.topology.TopologyBuilder;
+import backtype.storm.topology.base.BaseRichSpout;
+import backtype.storm.topology.base.BaseWindowedBolt;
+import backtype.storm.tuple.Fields;
+import backtype.storm.tuple.Tuple;
+import backtype.storm.tuple.Values;
+import backtype.storm.utils.Utils;
+import backtype.storm.windowing.TupleWindow;
+import storm.starter.bolt.PrinterBolt;
+
+import java.util.Map;
+import java.util.Random;
+
+import static backtype.storm.topology.base.BaseWindowedBolt.Count;
+import static backtype.storm.topology.base.BaseWindowedBolt.Duration;
+
+/**
+ * A sample topology that demonstrates the usage of {@link
backtype.storm.topology.IWindowedBolt}
+ * to calculate sliding window sum.
+ */
+public class SlidingWindowTopology {
+
+ /*
+ * emits random integers every 100 ms
+ */
+ private static class RandomIntegerSpout extends BaseRichSpout {
+ SpoutOutputCollector collector;
+
+ @Override
+ public void declareOutputFields(OutputFieldsDeclarer declarer) {
+ declarer.declare(new Fields("value"));
+ }
+
+ @Override
+ public void open(Map conf, TopologyContext context,
SpoutOutputCollector collector) {
+ this.collector = collector;
+ }
+
+ @Override
+ public void nextTuple() {
+ Utils.sleep(100);
+ Random rand = new Random();
+ Integer value = rand.nextInt(1000);
+ collector.emit(new Values(value));
+ }
+ }
+
+ /*
+ * Computes sliding window sum
+ */
+ private static class SlidingWindowSumBolt extends BaseWindowedBolt {
+ private int sum = 0;
+ private OutputCollector collector;
+
+ @Override
+ public void prepare(Map stormConf, TopologyContext context,
OutputCollector collector) {
+ this.collector = collector;
+ }
+
+ @Override
+ public void execute(TupleWindow inputWindow) {
+ System.out.println("Events in current window: " +
inputWindow.get().size());
+ for (Tuple tuple : inputWindow.getNew()) {
+ sum += (int) tuple.getValue(0);
+ }
+ for (Tuple tuple : inputWindow.getExpired()) {
+ sum -= (int) tuple.getValue(0);
+ }
+ collector.emit(new Values(sum));
--- End diff --
Oh I see you have the `getNew()` and the `getExpired()`. OK It would be
good to add a comment on that, because it was very confusing to me when I just
glanced through the code.
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