I have a tumbling window that aggregates into a process window function. Downstream there is a keyed process function.
[window aggregate into process function] -> keyed process function I am not quite sure how the keyed process knows which elements are at the boundary of the window. Is there a means to communicate that? Are watermarks the means by which we signal that either processing time or event time has finished an interval? Is it a watermark, that can be used to signal to the downstream operators the demarcating events? Are there other ways to do that?
