Package com.espertech.esper.common.internal.view.core

Interface DataWindowView

All Superinterfaces:
Iterable<EventBean>, View, Viewable, ViewDataVisitable
All Known Implementing Classes:
ExpressionBatchView, ExpressionViewBase, ExpressionWindowView, ExternallyTimedBatchView, ExternallyTimedWindowView, FirstEventView, FirstLengthWindowView, FirstTimeView, FirstUniqueByPropertyView, IntersectAsymetricView, IntersectBatchView, IntersectDefaultView, KeepAllView, LastEventView, LengthBatchView, LengthBatchViewRStream, LengthWindowView, LengthWindowViewRStream, RankWindowView, SortWindowView, TimeAccumView, TimeAccumViewRStream, TimeBatchView, TimeBatchViewRStream, TimeLengthBatchView, TimeOrderView, TimeWindowView, UnionAsymetricView, UnionView, UniqueByPropertyView
public interface DataWindowView extends View, ViewDataVisitable
Tag interface for data window views. Data window views follow the view interface but keep a window over the data received by their parent view. Data window view may keep length windows or time windows or other windows.

Data window views generally follow the following behavior:

They publish the data that was received as new data from their parent view directly or at a later time as new data to child views.

They publish the data that expires out of the window (for length or time reasons or other reasons) as old data to their child views.

They do not change event type compared to their parent view, since they only hold events temporarily.

They remove the data they receive as old data from their parent view out of the window and report the data removed as old data to child views (this is an optional capability for performance reasons).

Certain views may decide to attach only to data window views directly. One reason for this is that window limit the number of event instances kept in a collection. Without this limitation some views may not work correctly over time as events accumulate but are not removed from the view by means old data updates received from a parent data window.