/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
***************************************************************************************
*/
package com.espertech.esper.view;
/**
* 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.
* <p>
* Data window views generally follow the following behavior:
* <p>
* 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.
* <p>
* 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.
* <p>
* They do not change event type compared to their parent view, since they only hold events temporarily.
* <p>
* 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).
* <p>
* 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.
*/
public interface DataWindowView extends View, ViewDataVisitable, GroupableView {
}