net.esper.view.window
Class TimeWindowView

java.lang.Object
  extended by net.esper.view.ViewSupport
      extended by net.esper.view.window.TimeWindowView
All Implemented Interfaces:
java.lang.Iterable<EventBean>, ContextAwareView, EventCollection, View, Viewable, DataWindowView

public final class TimeWindowView
extends ViewSupport
implements ContextAwareView, DataWindowView

This view is a moving timeWindow extending the specified amount of milliseconds into the past. The view bases the timeWindow on the time obtained from the scheduling service. All incoming events receive a timestamp and are placed in a sorted map by timestamp. The view does not care about old data published by the parent view to this view. Events leave or expire from the time timeWindow by means of a scheduled callback registered with the scheduling service. Thus child views receive updates containing old data only asynchronously as the system-time-based timeWindow moves on. However child views receive updates containing new data as soon as the new data arrives.


Field Summary
 
Fields inherited from class net.esper.view.ViewSupport
parent
 
Constructor Summary
TimeWindowView()
          Default constructor - required by all views to adhere to the Java bean specification.
TimeWindowView(double secondsBeforeExpiry)
          Constructor.
TimeWindowView(int secondsBeforeExpiry)
          Constructor.
 
Method Summary
 java.lang.String attachesTo(Viewable parentView)
          Return null if the view will accept being attached to a particular object.
protected  void expire()
          This method removes (expires) objects from the window and schedules a new callback for the time when the next oldest message would expire from the window.
 ViewServiceContext getContext()
          Returns context holder.
 EventType getEventType()
          Provides metadata information about the type of object the event collection contains.
 long getMillisecondsBeforeExpiry()
          Returns the size of the time window in millisecond.
 java.util.Iterator<EventBean> iterator()
          Allows iteration through all elements in this event collection.
 void setContextAware(ViewServiceContext context)
          Set the services context containing service handles.
 void setMillisecondsBeforeExpiry(long millisecondsBeforeExpiry)
          Sets the size of the time window in millisecond.
 java.lang.String toString()
           
 void update(EventBean[] newData, EventBean[] oldData)
          Notify that data has been added or removed from the Viewable parent.
 
Methods inherited from class net.esper.view.ViewSupport
addView, dumpChildViews, dumpUpdateParams, findDescendent, getParent, getViews, hasViews, removeView, setParent, shallowCopyView, updateChildren, updateChildren
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface net.esper.view.View
getParent, setParent
 
Methods inherited from interface net.esper.view.Viewable
addView, getViews, hasViews, removeView
 

Constructor Detail

TimeWindowView

public TimeWindowView()
Default constructor - required by all views to adhere to the Java bean specification.


TimeWindowView

public TimeWindowView(int secondsBeforeExpiry)
Constructor.

Parameters:
secondsBeforeExpiry - is the number of seconds before events gets pushed out of the timeWindow as oldData in the update method.

TimeWindowView

public TimeWindowView(double secondsBeforeExpiry)
Constructor.

Parameters:
secondsBeforeExpiry - is the number of seconds before events gets pushed out of the timeWindow as oldData in the update method.
Method Detail

getMillisecondsBeforeExpiry

public final long getMillisecondsBeforeExpiry()
Returns the size of the time window in millisecond.

Returns:
size of window

setMillisecondsBeforeExpiry

public final void setMillisecondsBeforeExpiry(long millisecondsBeforeExpiry)
Sets the size of the time window in millisecond.

Parameters:
millisecondsBeforeExpiry - size of window

attachesTo

public final java.lang.String attachesTo(Viewable parentView)
Description copied from interface: View
Return null if the view will accept being attached to a particular object.

Specified by:
attachesTo in interface View
Parameters:
parentView - is the potential parent for this view
Returns:
null if this view can successfully attach to the parent, an error message if it cannot.

getEventType

public final EventType getEventType()
Description copied from interface: EventCollection
Provides metadata information about the type of object the event collection contains.

Specified by:
getEventType in interface EventCollection
Returns:
metadata for the objects in the collection

update

public final void update(EventBean[] newData,
                         EventBean[] oldData)
Description copied from interface: View
Notify that data has been added or removed from the Viewable parent. The last object in the newData array of objects would be the newest object added to the parent view. The first object of the oldData array of objects would be the oldest object removed from the parent view. If the call to update contains new (inserted) data, then the first argument will be a non-empty list and the second will be empty. Similarly, if the call is a notification of deleted data, then the first argument will be empty and the second will be non-empty. Either the newData or oldData will be non-null. This method won't be called with both arguments being null, but either one could be null. The same is true for zero-length arrays. Either newData or oldData will be non-empty. If both are non-empty, then the update is a modification notification. When update() is called on a view by the parent object, the data in newData will be in the collection of the parent, and its data structures will be arranged to reflect that. The data in oldData will not be in the parent's data structures, and any access to the parent will indicate that that data is no longer there.

Specified by:
update in interface View
Parameters:
newData - is the new data that has been added to the parent view
oldData - is the old data that has been removed from the parent view

expire

protected final void expire()
This method removes (expires) objects from the window and schedules a new callback for the time when the next oldest message would expire from the window.


iterator

public final java.util.Iterator<EventBean> iterator()
Description copied from interface: EventCollection
Allows iteration through all elements in this event collection. The iterator will return the elements in the collection in their natural order, or, if there is no natural ordering, in some unpredictable order.

Specified by:
iterator in interface java.lang.Iterable<EventBean>
Specified by:
iterator in interface EventCollection
Returns:
an iterator which will go through all current elements in the collection.

toString

public final java.lang.String toString()
Overrides:
toString in class java.lang.Object

setContextAware

public final void setContextAware(ViewServiceContext context)
Description copied from interface: ContextAwareView
Set the services context containing service handles.

Specified by:
setContextAware in interface ContextAwareView
Parameters:
context - with service handles

getContext

public final ViewServiceContext getContext()
Returns context holder.

Returns:
context