How to sort tuples in DataStream

[Saiph Kappa]

Hi,

I'm trying to do a simple application in Flink Stream to count the top N
words on a window-basis, but I don't know how to sort the words by their
frequency in Flink.

In spark streaming, I would do something like this:
«
val isAscending = true
stream.reduceByKeyAndWindow(reduceFunc, Seconds(10), Seconds
(10)).transform(_.sortByKey(isAscending)).map(_._2)
»

How can I do it in Flink Stream?

This is what I have so far:
«
val reduceFunc = (a: String, b: String) => {

  val aElems = a.split(Separator)
  val bElems = b.split(Separator)
  val result = a(params.aggParams.get.head.aggIndex).toInt +
b(params.aggParams.get.head.aggIndex).toInt
  result.toString
}

stream.keyBy(0).timeWindow(Time.seconds(10),
Time.seconds(10)).reduce(reduceFunc)
»


My stream is just a series of strings like "field1|field2|field3|..."

Thanks.