Application plug-in interface for handling continuous query events after they occur. The listener
has two methods, one that is called when there is an event satisfied by the CQ and the other
called when there is an error during CQ processing.
This method is invoked when an event is occurred on the region that satisfied the query
condition of this CQ. This event does not contain an error. If CQ is executed using
ExecuteWithInitialResults the returned result may already include the changes with respect to
this event. This could arise when updates are happening on the region while CQ registration is
in progress. The CQ does not block any region operation as it could affect the performance of
region operation. Its up to the application to synchronize between the region operation and CQ
registration to avoid duplicate event being delivered.
This method is invoked when there is an error during CQ processing. The error can appear while
applying query condition on the event. e.g if the event doesn't has attributes as specified in
the CQ query. This event does contain an error. The newValue may or may not be available, and
will be null if not available.