Quick update: I created a branch where I make the result type of WindowedStream operations more specific: https://github.com/aljoscha/flink/blob/windowed-stream-result-specific/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/datastream/WindowedStream.java
We would need this for the "lateStream()" API without the explicit OutputTag. It seems the backwards compatibility checker doesn't like this and complains about breaking binary backwards compatibility. +Robert Metzger <rmetz...@apache.org> Do you have an idea what we could do there? On Tue, 28 Feb 2017 at 12:39 Ufuk Celebi <u...@apache.org> wrote: > On Tue, Feb 28, 2017 at 11:38 AM, Aljoscha Krettek <aljos...@apache.org> > wrote: > > I see the ProcessFunction as a bit of the generalised future of FlatMap, > so > > to me it makes sense to only allow side outputs on the ProcessFunction > but > > I'm open for anything. If we decide for this I'm happy with an additional > > method on Collector. > > I think it's best to restrict this to ProcessFunction after all (given > that we allow it for non-keyed streams, etc.). ;-) >