net.esper.view.window
Class TimeBatchView

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

public final class TimeBatchView
extends ViewSupport
implements ContextAwareView

A data view that aggregates events in a stream and releases them in one batch at every specified time interval. The view works similar to a time_window but in not continuous. The view releases the batched events after the interval as new data to child views. The prior batch if not empty is released as old data to child view. The view doesn't release intervals with no old or new data. It also does not getSelectListEvents old data published by a parent view. For example, we want to calculate the average of IBM stock every hour, for the last hour. The view accepts 2 parameter combinations. (1) A time interval is supplied with a reference point - based on this point the intervals are set. (1) A time interval is supplied but no reference point - the reference point is set when the first event arrives. If there are no events in the current and prior batch, the view will not invoke the update method of child views. In that case also, no next callback is scheduled with the scheduling service until the next event arrives.


Field Summary
 
Fields inherited from class net.esper.view.ViewSupport
parent
 
Constructor Summary
TimeBatchView()
          Default constructor - required by all views to adhere to the Java bean specification.
TimeBatchView(double secIntervalSize)
          Constructor.
TimeBatchView(double secIntervalSize, java.lang.Long referencePoint)
          Constructor.
TimeBatchView(int secIntervalSize)
          Constructor.
TimeBatchView(int secIntervalSize, java.lang.Long referencePoint)
          Constructor.
 
Method Summary
 java.lang.String attachesTo(Viewable parentView)
          Return null if the view will accept being attached to a particular object.
protected static long computeWaitMSec(long current, long reference, long interval)
          Given a current time and a reference time and an interval size, compute the amount of milliseconds till the next interval.
 EventType getEventType()
          Provides metadata information about the type of object the event collection contains.
 java.lang.Long getInitialReferencePoint()
          Gets the reference point to use to anchor interval start and end dates to.
 long getMsecIntervalSize()
          Returns the interval size in milliseconds.
 ViewServiceContext getViewServiceContext()
          Returns the context instances used by the view.
 java.util.Iterator<EventBean> iterator()
          Allows iteration through all elements in this event collection.
protected  void sendBatch()
          This method updates child views and clears the batch of events.
 void setInitialReferencePoint(java.lang.Long initialReferencePoint)
          Sets the reference point to use to anchor interval start and end dates to.
 void setMsecIntervalSize(long msecIntervalSize)
          Sets the interval size in milliseconds.
 void setViewServiceContext(ViewServiceContext viewServiceContext)
          Set the services context containing service handles.
 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
 

Constructor Detail

TimeBatchView

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


TimeBatchView

public TimeBatchView(int secIntervalSize)
Constructor.

Parameters:
secIntervalSize - is the number of seconds to batch events for.

TimeBatchView

public TimeBatchView(int secIntervalSize,
                     java.lang.Long referencePoint)
Constructor.

Parameters:
secIntervalSize - is the number of milliseconds to batch events for
referencePoint - is the reference point onto which to base intervals.

TimeBatchView

public TimeBatchView(double secIntervalSize)
Constructor.

Parameters:
secIntervalSize - is the number of seconds to batch events for.

TimeBatchView

public TimeBatchView(double secIntervalSize,
                     java.lang.Long referencePoint)
Constructor.

Parameters:
secIntervalSize - is the number of seconds to batch events for
referencePoint - is the reference point onto which to base intervals.
Method Detail

getMsecIntervalSize

public final long getMsecIntervalSize()
Returns the interval size in milliseconds.

Returns:
batch size

setMsecIntervalSize

public final void setMsecIntervalSize(long msecIntervalSize)
Sets the interval size in milliseconds.

Parameters:
msecIntervalSize - batch size

getInitialReferencePoint

public final java.lang.Long getInitialReferencePoint()
Gets the reference point to use to anchor interval start and end dates to.

Returns:
is the millisecond reference point.

setInitialReferencePoint

public final void setInitialReferencePoint(java.lang.Long initialReferencePoint)
Sets the reference point to use to anchor interval start and end dates to.

Parameters:
initialReferencePoint - is the millisecond reference point.

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

getViewServiceContext

public ViewServiceContext getViewServiceContext()
Description copied from interface: ContextAwareView
Returns the context instances used by the view.

Specified by:
getViewServiceContext in interface ContextAwareView
Returns:
context instance

setViewServiceContext

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

Specified by:
setViewServiceContext in interface ContextAwareView
Parameters:
viewServiceContext - with service handles

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

sendBatch

protected final void sendBatch()
This method updates child views and clears the batch of events. We schedule a new callback at this time if there were events in the batch.


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

computeWaitMSec

protected static long computeWaitMSec(long current,
                                      long reference,
                                      long interval)
Given a current time and a reference time and an interval size, compute the amount of milliseconds till the next interval.

Parameters:
current - is the current time
reference - is the reference point
interval - is the interval size
Returns:
milliseconds after current time that marks the end of the current interval