On Fri, Jun 3, 2016 at 6:47 AM, Kostas Kloudas <k.klou...@data-artisans.com> wrote:
> To see a relatively more complex example of such a trigger and how to > implement it, > you can have a look at this implementation: > https://github.com/dataArtisans/beam_comp/blob/master/src/main/java/com/dataartisans/beam_comparison/customTriggers/EventTimeTriggerWithEarlyAndLateFiring.java > I've modified this trigger so that firing are suppressed unless there are new events between timers. This can significantly reduce the outputted events, which could mean much reduced writes to a downstream data store. See https://gist.github.com/eliaslevy/ec840444607b9a5dd5aa3eb2cdd77932. Also, I find the accumulating behavior somewhat unintuitive as when disabled it only purges when the time window ends. When discarding is in effect, it seems more natural for purging it to occur at each firing, whether early, at the windows event time end, or late. Otherwise, you may end up with output events of different semantics. E.g. with the current behavior if you are implementing a counter early firing will result on partial counts until the window end, after that late will give you partial counts of the delta from the window end count. It would be more consistent to either generate partial counts at all firing or deltas at all firing, so that the output of the operator can be processes the same downstream.
