public interface CellSetListener
NOTE: This functionality is experimental and is subject to change or removal without notice.
The client can ask the server to provide the listener with a specific
granularity of events, but the server can decline to
provide that granularity.
Fine granularity deals with changes such as cell values changing (and reports the before and after value, before and after formatted value), positions being deleted, positions being changed.
When an atomic change happens on the server (say a cache flush, if the
server is mondrian) then an event will arrive on the client containing all of
those changes. Although
CellSetListener.CellSetChange.getAxisChanges() return lists, the client should assume
that all of the events in these lists simultaneously.
At any point, the server is free to throw up its hands and say 'there are
too many changes' by sending null values for
getAxisChanges. This prevents situations where there are huge numbers
of changes that might overwhelm the server, the network link, or the client,
such as might happen if a large axis is re-sorted.
The client should always be ready for that to happen (even for providers that claim to provide fine granularity events), and should re-execute the query to get the cell set. In fact, we recommend that clients re-execute the query to get a new cellset whenever they get an event. Then the client can use the details in the event to highlight cells that have changed.
The purpose of registering a listener before creating a cell set is to ensure that no events "leak out" between creating a cell set and registering a listener, or while a statement is being re-executed to produce a new cell set.
methods are provided so that the listener knows what is going on when a
statement is re-executed. In particular, suppose a statement receives an
change event decides to re-execute. The listener is attached to the
statement, so receives notifications about both old and new cell sets. The
driver implicitls closes the previous cell set and calls
cellSetClosed, then calls
cellSetOpened with the new cell
If changes are occurring regularly on the server, there will soon be a
cellSetChanged(org.olap4j.CellSetListener.CellSetChange). It is important to note that this event
contains only changes that have occurred since the new cell set was opened.
The granularity parameter is provided to
for the server's benefit. If granularity is only
the server may be able to store less information in order to track the cell
|Modifier and Type||Interface and Description|
Description of changes that have occurred to the cell set.
Granularity of notifications that should be sent to a cellset listener.
|Modifier and Type||Method and Description|
Invoked when a cell set has changed.
Invoked when a cell set is closed.
Invoked when a cell set is opened.
void cellSetOpened(CellSet cellSet)
cellSet- Cell set
void cellSetClosed(CellSet cellSet)
cellSet- Cell set