Another important point of windowing in Apache Beam concerns triggers. Thanks to them we can freely control when the window results are computed.
Data, especially in streaming applications, can very often arrive on late to the processing pipeline. Despite of that, Apache Beam is able to handle this case pretty easily thanks to watermark mechanism.
As mentioned in one of the first posts about Apache Beam, the concept of window is a key element in its data processing logic. Even for bounded data a default window called global is defined. For the unbounded one the variety of windows is much bigger.
