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https://issues.apache.org/jira/browse/FLINK-10167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16587179#comment-16587179
]
Aljoscha Krettek commented on FLINK-10167:
------------------------------------------
Yes, your right that this is a problem but only when working with "values". If
you change it to this it will work:
{code}
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)
.map( in => (in / 10, in) )
.keyBy(_._1)
.window(ProcessingTimeSessionWindows.withGap(Time.minutes(1)))
.reduce(
(a: (Int, Int), b: (Int, Int)) => (a._1, a._2 + a._2) ,
(key: Int, window: TimeWindow, items: Iterable[(Int, Int)], out:
Collector[String]) => s"${key}: ${items}"
)
.map(println(_))
env.execute(jobName)
}
}
{code}
> SessionWindows not compatible with typed DataStreams in scala
> -------------------------------------------------------------
>
> Key: FLINK-10167
> URL: https://issues.apache.org/jira/browse/FLINK-10167
> Project: Flink
> Issue Type: Bug
> Reporter: Andrew Roberts
> Priority: Major
>
> I'm trying to construct a trivial job that uses session windows, and it looks
> like the data type parameter is hardcoded to `Object`/`AnyRef`. Due to the
> invariance of java classes in scala, this means that we can't use the
> provided SessionWindow helper classes in scala on typed streams.
>
> Example job:
> {code:java}
> import org.apache.flink.api.scala._
> import org.apache.flink.streaming.api.scala.{DataStream,
> StreamExecutionEnvironment}
> import
> org.apache.flink.streaming.api.windowing.assigners.ProcessingTimeSessionWindows
> import org.apache.flink.streaming.api.windowing.time.Time
> import org.apache.flink.streaming.api.windowing.windows.{TimeWindow, Window}
> import org.apache.flink.util.Collector
> object TestJob {
> val jobName = "TestJob"
> def main(args: Array[String]): Unit = {
> val env = StreamExecutionEnvironment.getExecutionEnvironment
> env.fromCollection(Range(0, 100).toList)
> .keyBy(_ / 10)
> .window(ProcessingTimeSessionWindows.withGap(Time.minutes(1)))
> .reduce(
> (a: Int, b: Int) => a + b,
> (key: Int, window: Window, items: Iterable[Int], out:
> Collector[String]) => s"${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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