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https://issues.apache.org/jira/browse/FLINK-8384?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16327310#comment-16327310
]
ASF GitHub Bot commented on FLINK-8384:
---------------------------------------
Github user sunjincheng121 commented on a diff in the pull request:
https://github.com/apache/flink/pull/5295#discussion_r161798960
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/assigners/DynamicEventTimeSessionWindows.java
---
@@ -0,0 +1,101 @@
+/*
+ * 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 org.apache.flink.streaming.api.windowing.assigners;
+
+import org.apache.flink.api.common.ExecutionConfig;
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
+import org.apache.flink.streaming.api.windowing.triggers.Trigger;
+import
org.apache.flink.streaming.api.windowing.triggers.TypedEventTimeTrigger;
+import org.apache.flink.streaming.api.windowing.windows.TimeWindow;
+
+import java.util.Collection;
+import java.util.Collections;
+
+/**
+ * A {@link WindowAssigner} that windows elements into sessions based on
the timestamp of the
+ * elements. Windows cannot overlap.
+ *
+ * <p>For example, in order to window into windows with a dynamic time gap:
+ * <pre> {@code
+ * DataStream<Tuple2<String, Integer>> in = ...;
+ * KeyedStream<String, Tuple2<String, Integer>> keyed = in.keyBy(...);
+ * WindowedStream<Tuple2<String, Integer>, String, TimeWindows> windowed =
+ * keyed.window(DynamicEventTimeSessionWindows.withDynamicGap({@link
SessionWindowTimeGapExtractor }));
+ * } </pre>
+ *
+ * @param <T> The type of the input elements
+ */
+public class DynamicEventTimeSessionWindows<T> extends
MergingWindowAssigner<T, TimeWindow> {
+ private static final long serialVersionUID = 1L;
--- End diff --
Can we change `MergingWindowAssigner<T, TimeWindow> ` to
`MergingWindowAssigner<Object, TimeWindow> ` ? if so we can reuse the
`EventTimeTrigger`.
> Session Window Assigner with Dynamic Gaps
> -----------------------------------------
>
> Key: FLINK-8384
> URL: https://issues.apache.org/jira/browse/FLINK-8384
> Project: Flink
> Issue Type: Improvement
> Components: Streaming
> Reporter: Dyana Rose
> Priority: Minor
>
> *Reason for Improvement*
> Currently both Session Window assigners only allow a static inactivity gap.
> Given the following scenario, this is too restrictive:
> * Given a stream of IoT events from many device types
> * Assume each device type could have a different inactivity gap
> * Assume each device type gap could change while sessions are in flight
> By allowing dynamic inactivity gaps, the correct gap can be determined in the
> [assignWindows
> function|https://github.com/apache/flink/blob/master/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/assigners/EventTimeSessionWindows.java#L59]
> by passing the element currently under consideration, the timestamp, and the
> context to a user defined function. This eliminates the need to create
> unwieldy work arounds if you only have static gaps.
> Dynamic Session Window gaps should be available for both Event Time and
> Processing Time streams.
> (short preliminary discussion:
> https://lists.apache.org/thread.html/08a011c0039e826343e9be0b1bb4e0000cfc2e12976bc65f8a43ee88@%3Cdev.flink.apache.org%3E)
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