Hi Yassine, regarding 1. The close() method of the RichFoldFunction will only be called at the very end of your streaming job, so in practise it will never be called. This is there because of batch jobs, where you have an actual end in your processing.
regarding 2. I'm afraid you came across a bug: https://issues.apache.org/jira/browse/FLINK-3869. We can't change this right now because we cannot break API instability but right at the end of this issue I'm proposing a different solution that we'll hopefully get in for the next release. Cheers, Aljoscha On Wed, 2 Nov 2016 at 10:42 Yassine MARZOUGUI <y.marzou...@mindlytix.com> wrote: > Hi all, > > I have a couple questions about FoldFunction and WindowFunction: > > 1. When using a RichFoldFunction after a window as in > keyedStream.window().fold(new > RichFoldFunction()), is the close() method called after each window or > after all the windows for that key are fired? > > 2. When applying a FoldFunction to a window followed by a WindowFunction > via apply > <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/datastream/WindowedStream.html#apply-R-org.apache.flink.api.common.functions.FoldFunction-org.apache.flink.streaming.api.functions.windowing.WindowFunction->(R > initialValue, > FoldFunction > <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/api/common/functions/FoldFunction.html> > <T > <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/datastream/WindowedStream.html>,R> > foldFunction, > WindowFunction > <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/functions/windowing/WindowFunction.html> > <R,R,K > <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/datastream/WindowedStream.html> > ,W > <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/datastream/WindowedStream.html> > > function), why should the output of the WindowFunction be of the same > type as the input? It would be practical to have a different output type > sometimes, for example one would fold tuples in the FoldFunction and then > process the (only) aggregated tuple in the Window function and emit an > Integer. > > Best, > Yassine >
