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Posted to issues@flink.apache.org by "Robert Metzger (JIRA)" <ji...@apache.org> on 2019/02/28 16:16:00 UTC
[jira] [Updated] (FLINK-10167) SessionWindows not compatible with
typed DataStreams in scala
[ https://issues.apache.org/jira/browse/FLINK-10167?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Robert Metzger updated FLINK-10167:
-----------------------------------
Component/s: API / DataStream
> SessionWindows not compatible with typed DataStreams in scala
> -------------------------------------------------------------
>
> Key: FLINK-10167
> URL: https://issues.apache.org/jira/browse/FLINK-10167
> Project: Flink
> Issue Type: Bug
> Components: API / DataStream
> Affects Versions: 1.7.1
> Reporter: Andrew Roberts
> Priority: Major
>
> I'm trying to construct a trivial job that uses session windows, and it looks like the data type parameter is hardcoded to `Object`/`AnyRef`. Due to the invariance of java classes in scala, this means that we can't use the provided SessionWindow helper classes in scala on typed streams.
>
> Example job:
> {code:java}
> import org.apache.flink.api.scala._
> import org.apache.flink.streaming.api.scala.{DataStream, StreamExecutionEnvironment}
> import org.apache.flink.streaming.api.windowing.assigners.ProcessingTimeSessionWindows
> import org.apache.flink.streaming.api.windowing.time.Time
> import org.apache.flink.streaming.api.windowing.windows.{TimeWindow, Window}
> import org.apache.flink.util.Collector
> object TestJob {
> val jobName = "TestJob"
> def main(args: Array[String]): Unit = {
> val env = StreamExecutionEnvironment.getExecutionEnvironment
> env.fromCollection(Range(0, 100).toList)
> .keyBy(_ / 10)
> .window(ProcessingTimeSessionWindows.withGap(Time.minutes(1)))
> .reduce(
> (a: Int, b: Int) => a + b,
> (key: Int, window: Window, items: Iterable[Int], out: Collector[String]) => s"${key}: ${items}"
> )
> .map(println(_))
> env.execute(jobName)
> }
> }{code}
>
> Compile error:
> {code:java}
> [error] found : org.apache.flink.streaming.api.windowing.assigners.ProcessingTimeSessionWindows
> [error] required: org.apache.flink.streaming.api.windowing.assigners.WindowAssigner[_ >: Int, ?]
> [error] Note: Object <: Any (and org.apache.flink.streaming.api.windowing.assigners.ProcessingTimeSessionWindows <: org.apache.flink.streaming.api.windowing.assigners.MergingWindowAssigner[Object,org.apache.flink.streaming.api.windowing.windows.TimeWindow]), but Java-defined class WindowAssigner is invariant in type T.
> [error] You may wish to investigate a wildcard type such as `_ <: Any`. (SLS 3.2.10)
> [error] .window(ProcessingTimeSessionWindows.withGap(Time.minutes(1))){code}
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