public class ExternallyTimedWindowView extends ViewSupport implements DataWindowView, CloneableView
The view is completely driven by timestamp values that are supplied by the events it receives, and does not use the schedule service time. It requires a field name as parameter for a field that returns ascending long-type timestamp values. It also requires a long-type parameter setting the time length in milliseconds of the time window. Events are expected to provide long-type timestamp values in natural order. The view does itself not use the current system time for keeping track of the time window, but just the timestamp values supplied by the events sent in.
The arrival of new events with a newer timestamp then past events causes the window to be re-evaluated and the oldest events pushed out of the window. Ie. Assume event X1 with timestamp T1 is in the window. When event Xn with timestamp Tn arrives, and the window time length in milliseconds is t, then if ((Tn - T1) > t == true) then event X1 is pushed as oldData out of the window. It is assumed that events are sent in in their natural order and the timestamp values are ascending.
| Modifier and Type | Field and Description |
|---|---|
protected AgentInstanceViewFactoryChainContext |
agentInstanceViewFactoryContext |
protected TimeWindow |
timeWindow |
EMPTY_VIEW_ARRAY, parent| Constructor and Description |
|---|
ExternallyTimedWindowView(ExternallyTimedWindowViewFactory externallyTimedWindowViewFactory,
ExprNode timestampExpression,
ExprEvaluator timestampExpressionEval,
ExprTimePeriodEvalDeltaConst timeDeltaComputation,
ViewUpdatedCollection viewUpdatedCollection,
AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext)
Constructor.
|
| Modifier and Type | Method and Description |
|---|---|
View |
cloneView()
Duplicates the view.
|
EventType |
getEventType()
Provides metadata information about the type of object the event collection contains.
|
ExprTimePeriodEvalDeltaConst |
getTimeDeltaComputation() |
ExprNode |
getTimestampExpression()
Returns the field name to get timestamp values from.
|
ViewFactory |
getViewFactory() |
ViewUpdatedCollection |
getViewUpdatedCollection() |
boolean |
isEmpty()
Returns true to indicate the window is empty, or false if the view is not empty.
|
Iterator<EventBean> |
iterator()
Allows iteration through all elements in this event collection.
|
String |
toString() |
void |
update(EventBean[] newData,
EventBean[] oldData)
Notify that data has been added or removed from the Viewable parent.
|
void |
visitView(ViewDataVisitor viewDataVisitor) |
addView, addView, dumpChildViews, dumpUpdateParams, dumpUpdateParams, findDescendent, findViewIndex, getParent, getViews, hasViews, removeAllViews, removeView, removeView, setParent, updateChildren, updateChildrenclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitaddView, getViews, hasViews, removeAllViews, removeViewforEach, spliteratorprotected final TimeWindow timeWindow
protected AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext
public ExternallyTimedWindowView(ExternallyTimedWindowViewFactory externallyTimedWindowViewFactory, ExprNode timestampExpression, ExprEvaluator timestampExpressionEval, ExprTimePeriodEvalDeltaConst timeDeltaComputation, ViewUpdatedCollection viewUpdatedCollection, AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext)
timestampExpression - is the field name containing a long timestamp value
that should be in ascending order for the natural order of events and is intended to reflect
System.currentTimeInMillis but does not necessarily have to.
out of the window as oldData in the update method. The view compares
each events timestamp against the newest event timestamp and those with a delta
greater then secondsBeforeExpiry are pushed out of the window.viewUpdatedCollection - is a collection that the view must update when receiving eventsexternallyTimedWindowViewFactory - for copying this view in a group-byagentInstanceViewFactoryContext - context for expression evalauationtimeDeltaComputation - delta computationtimestampExpressionEval - timestamp expr evalpublic View cloneView()
CloneableViewExpected to return a same view in initialized state for grouping.
cloneView in interface CloneableViewpublic final ExprNode getTimestampExpression()
public ExprTimePeriodEvalDeltaConst getTimeDeltaComputation()
public final EventType getEventType()
EventCollectiongetEventType in interface EventCollectionpublic final void update(EventBean[] newData, EventBean[] oldData)
ViewIf 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.
public final Iterator<EventBean> iterator()
EventCollectioniterator in interface EventCollectioniterator in interface Iterable<EventBean>public void visitView(ViewDataVisitor viewDataVisitor)
visitView in interface ViewDataVisitablepublic boolean isEmpty()
public ViewUpdatedCollection getViewUpdatedCollection()
public ViewFactory getViewFactory()
getViewFactory in interface GroupableView