Package com.streambase.liveview.client

Interface QueryListener

All Superinterfaces:

EventListener

All Known Implementing Classes:

AbstractBatchedQueryListener, AbstractQueryListener, CompositeQueryListener, DeleteQueryListener, LiveResult, QueryListenerWrapper, SnapshotQueryListener

public interface QueryListener
extends EventListener

A query listener interface must be provided when registering a query. The server will make call backs to this interface with query events. If you are only interested in a subset of events consider using the AbstractQueryListener.

All tuple events between snapshotBegin(BeginSnapshotEvent) and snapshotEnd(EndSnapshotEvent) are tupleAdded(TupleAddedEvent) events.

If the LiveViewQueryType of the query is SNAPSHOT_AND_CONTINUOUS, then the QueryListener after the snapshotEnd(EndSnapshotEvent) can receive any number of tupleAdded(TupleAddedEvent), tupleUpdated(TupleUpdatedEvent), and tupleRemoved(TupleRemovedEvent), in any order.

It is also possible that the query results will need to be reset, in which case the QueryListener might receive a new snapshotBegin(BeginSnapshotEvent). This signals that all previous data should be discarded, and the entire process will start fresh. For example, if the query was made through a LiveViewMultiConnection, and the server that was servicing the query has gone down, and a new server has since picked the connection back up, the snapshotBegin(BeginSnapshotEvent) will signal the beginning of a new result set coming from the new server.

At any point the QueryListener might receive a exceptionRaised(QueryExceptionEvent), if some unrecoverable failure has happened. In that case, the query will be closed and no more TupleEvents will happen. If snapshotEnd(EndSnapshotEvent) has not yet been called, it won't be. The exception will be the final callback made to the QueryListener.

Note that callbacks should return quickly. In some situations, long running callbacks can trigger heartbeat failures and/or other connection problems, particularly in the face of high data rates.

Method Summary

Modifier and Type	Method	Description
default void	aggMarkBegin(BeginAggMarkEvent event)	Event to indicate that the set of aggregation results may be changing so some results may be from an older generation while other may be from a newer one.
default void	aggMarkEnd(EndAggMarkEvent event)	Event to indicate that the set of aggregation results since the last aggMarkBegin event are now consistent and will not change until the next aggMarkBegin.
void	deleteBegin(BeginDeleteEvent event)	Event to indicate the start of delete query.
void	deleteEnd(EndDeleteEvent event)	Event to indicate the delete query is complete.
void	exceptionRaised(QueryExceptionEvent event)	Event when an exception occurs during the query.
void	queryClosed(QueryClosedEvent event)	Event when a query being listened to is closed.
void	snapshotBegin(BeginSnapshotEvent event)	Event to indicate the start of the result snapshot.
void	snapshotEnd(EndSnapshotEvent event)	Event to indicate the query snapshot is complete.
void	tupleAdded(TupleAddedEvent event)	Event when a new tuple is added to the result.
void	tupleRemoved(TupleRemovedEvent event)	Event when an existing tuple is removed from the result.
void	tupleUpdated(TupleUpdatedEvent event)	Event when an existing tuple in the result is updated.

Method Details

tupleAdded

void tupleAdded(TupleAddedEvent event)

Event when a new tuple is added to the result.

Parameters:

event - add event

tupleUpdated

void tupleUpdated(TupleUpdatedEvent event)

Event when an existing tuple in the result is updated.

Parameters:

event - update event

tupleRemoved

void tupleRemoved(TupleRemovedEvent event)

Event when an existing tuple is removed from the result.

Parameters:

event - remove event

snapshotBegin

void snapshotBegin(BeginSnapshotEvent event)

Event to indicate the start of the result snapshot. This is the first method called when a query starts returning results, but this method is also called to indicate a reset (a complete restart of the query.)

Parameters:

event - snapshot begin

snapshotEnd

void snapshotEnd(EndSnapshotEvent event)

Event to indicate the query snapshot is complete.

Parameters:

event - snapshot end

deleteBegin

void deleteBegin(BeginDeleteEvent event)

Event to indicate the start of delete query.

Parameters:

event - delete begin

Since:

1.5.2

deleteEnd

void deleteEnd(EndDeleteEvent event)

Event to indicate the delete query is complete.

Parameters:

event - delete end

Since:

1.5.2

aggMarkEnd

default void aggMarkEnd(EndAggMarkEvent event)

Event to indicate that the set of aggregation results since the last aggMarkBegin event are now consistent and will not change until the next aggMarkBegin.

Parameters:

event - the EndAggMarkEvent

Since:

7.7.4

aggMarkBegin

default void aggMarkBegin(BeginAggMarkEvent event)

Event to indicate that the set of aggregation results may be changing so some results may be from an older generation while other may be from a newer one.

Parameters:

event - the BeginAggMarkEvent

Since:

7.7.4

exceptionRaised

void exceptionRaised(QueryExceptionEvent event)

Event when an exception occurs during the query. Since 1.3, reaching the row limit is considered an exception.

Parameters:

event - exception event

Since:

1.3 - this method will be invoked when the query row limit is reached (earlier versions would simply end streaming results)

queryClosed

void queryClosed(QueryClosedEvent event)

Event when a query being listened to is closed.

Parameters:

event - query closed event