All Packages  Class Hierarchy  This Package  Previous  Next  Index

Interface javax.infobus.InfoBusDataController

public interface InfoBusDataController

Internally, an InfoBus maintains a set of InfoBusDataControllers that are active on the bus and passes an incoming request to each of them until notified that further distribution is unnecessary (via getStopFlag). The set of controllers will always contain a DefaultController, which is always the last to receive requests that have not been handled by another controller.

Version:

$Revision: 1.8 $ $Date: 24 Feb 1998 17:04:34 $

See Also:

InfoBusEventListener, InfoBus

addDataConsumer(InfoBusDataConsumer)

Called by the InfoBus each time an InfoBusDataConsumer joins the InfoBus after the DataController did, to update the DataController of the addition of the consumer.

addDataProducer(InfoBusDataProducer)

Called by the InfoBus each time an InfoBusDataProducer joins the InfoBus after the DataController did, to update the DataController of the addition of the producer.

findDataItem(String, DataFlavor[], InfoBusDataConsumer, Vector)

Called by the InfoBus when a consumer wishes to find a DataItem matching the given dataItemName.

findMultipleDataItems(String, DataFlavor[], InfoBusDataConsumer, Vector)

Called by the InfoBus when a consumer wishes to find ALL DataItems matching the given dataItemName.

fireItemAvailable(String, DataFlavor[], InfoBusDataProducer)

Called by the InfoBus when the producer "source" requests the distribution of an InfoBusItemAvailable event to consumers on the InfoBus.

fireItemRevoked(String, InfoBusDataProducer)

Called by the InfoBus when a producer requests the distribution of an InfoBusItemRevoked event to consumers on the InfoBus.

removeDataConsumer(InfoBusDataConsumer)

Called by the InfoBus each time an InfoBusDataConsumer leaves the InfoBus to alert the DataController of the change.

removeDataProducer(InfoBusDataProducer)

Called by the InfoBus each time an InfoBusDataProducer leaves the InfoBus to alert the DataController of the change.

setConsumerList(Vector)

Called once by the InfoBus when the DataController adds itself.

setProducerList(Vector)

Called once by the InfoBus when the DataController adds itself.

 public abstract void setConsumerList(Vector consumers)

Called once by the InfoBus when the DataController adds itself. Presents the DataController with the InfoBus's consumer list, which at that point contains the consumers that joined the bus before the controller did. The DataController should make a copy reference to any consumers that it wishes to manage.

Parameters:

consumers - the Vector of InfoBusDataConsumers held by the InfoBus when the DataController added itself to the bus

 public abstract void setProducerList(Vector producers)

Called once by the InfoBus when the DataController adds itself. Presents the DataController with the InfoBus's producer list, which at that point contains the producers that joined the bus before the controller did. The DataController should make a copy reference to any producers that it wishes to manage.

Parameters:

producers - the Vector of InfoBusDataProducers held by the InfoBus when the DataController added itself to the bus

 public abstract void addDataConsumer(InfoBusDataConsumer consumer)

Called by the InfoBus each time an InfoBusDataConsumer joins the InfoBus after the DataController did, to update the DataController of the addition of the consumer. If the DataController wishes to manage the new consumer it should add a reference to its own private consumer list.

Parameters:

consumer - the DataConsumer now joining the InfoBus

 public abstract void addDataProducer(InfoBusDataProducer producer)

Called by the InfoBus each time an InfoBusDataProducer joins the InfoBus after the DataController did, to update the DataController of the addition of the producer. If the DataController wishes to manage the new producer it should add a reference to its own private producer list.

Parameters:

producer - the DataProducer now joining the InfoBus

 public abstract void removeDataConsumer(InfoBusDataConsumer consumer)

Called by the InfoBus each time an InfoBusDataConsumer leaves the InfoBus to alert the DataController of the change. The DataController must remove all references to the consumer from its private lists and ensure that the controller sends no further InfoBusEvents to the consumer.

Parameters:

consumer - the DataConsumer that is leaving the InfoBus

 public abstract void removeDataProducer(InfoBusDataProducer producer)

Called by the InfoBus each time an InfoBusDataProducer leaves the InfoBus to alert the DataController of the change. The DataController must remove all references to the producer from its private lists and ensure that the controller sends no further InfoBusEvents to the producer.

Parameters:

producer - the DataProducer that is leaving the InfoBus

 public abstract boolean fireItemAvailable(String dataItemName,
                                           DataFlavor flavors[],
                                           InfoBusDataProducer source)

Called by the InfoBus when the producer "source" requests the distribution of an InfoBusItemAvailable event to consumers on the InfoBus. The DataController decides whether any of the consumers it is managing are potential targets for the Available event, and calls one of the two target-specific fireItemAvailable methods on its InfoBus to create and send the event to those consumers.

Note that the DataController should copy the source field it receives to any target-specific method that the controller calls

Parameters:

dataItemName - the name of the DataItem made available by source

flavors - the DataFlavors the source makes available (optional, possibly null)

source - the Producer offering the DataItem

Returns:

Stop Code: if true, do not process this request further; if false, continue to next DataController

See Also:

javax.infobus.InfoBus.fireItemAvailable, javax.infobus.InfoBus.fireItemAvailable

 public abstract boolean fireItemRevoked(String dataItemName,
                                         InfoBusDataProducer producer)

Called by the InfoBus when a producer requests the distribution of an InfoBusItemRevoked event to consumers on the InfoBus. The DataController decides whether any of the consumers it is managing are potential targets for the Revoked event, and calls one of the two target-specific fireItemRevoked methods on its InfoBus to create and send the event to those consumers.

Note that the DataController should copy the source field it receives to any target-specific method that the controller calls

Parameters:

dataItemName - the name of the DataItem being revoked by source

producer - the Producer no longer offering the DataItem

Returns:

Stop Code: if true, do not process this request further; if false, continue to next DataController

See Also:

javax.infobus.InfoBus.fireItemRevoked, javax.infobus.InfoBus.fireItemRevoked

 public abstract boolean findDataItem(String dataItemName,
                                      DataFlavor flavors[],
                                      InfoBusDataConsumer consumer,
                                      Vector foundItem)

Called by the InfoBus when a consumer wishes to find a DataItem matching the given dataItemName. The DataController decides whether any of the producers it is managing are potential sources for the requested data, and issues an InfoBusItemRequestedEvent to them by calling one of the target-specific findDataItem methods on its InfoBus. The first non-null response should be stored in foundItem; the InfoBus only retrieves element 0 from foundItem; any other objects stored there are ignored.

If the DataController returns a DataItem from this method, the InfoBus will stop seeking the data and return that DataItem (calling no other controllers). If foundItem is empty when the call completes, the InfoBus uses the boolean return value to determine whether to continue polling controllers: if true, polling stops and null is returned to the consumer.

Parameters:

dataItemName - the name of the DataItem that the consumer is seeking

flavors - the DataFlavors the consumer prefers (optional, possibly null)

consumer - the Consumer seeking the data

foundItem - a Vector for storing the result which will be empty when the method is called

Returns:

Stop Code: if true, do not process this request further; if false, continue to next DataController. Ignored if foundDataItem is not empty.

See Also:

javax.infobus.InfoBus.findDataItem, javax.infobus.InfoBus.findDataItem

 public abstract boolean findMultipleDataItems(String dataItemName,
                                               DataFlavor flavors[],
                                               InfoBusDataConsumer consumer,
                                               Vector foundItems)

Called by the InfoBus when a consumer wishes to find ALL DataItems matching the given dataItemName. The DataController decides whether any of the producers it is managing are potential sources for the requested data, and issues an InfoBusItemRequestedEvent to each by calling a target-specific findDataItem method on its InfoBus.

All non-null responses should be stored in the foundItems Vector. The responses returned by this controller will be concatenated with those of the controllers called before and after this one. If the return value is true, no further controllers will be polled.

Parameters:

dataItemName - the name of the DataItem that the consumer is seeking

flavors - the DataFlavors the consumer prefers (optional, possibly null)

consumer - the Consumer seeking the data

foundItems - a Vector for storing all non-null results; will be empty when the method is called

Returns:

Stop Code: if true, do not process this request further; if false, continue to next DataController.

See Also:

javax.infobus.InfoBus.findDataItem, javax.infobus.InfoBus.findDataItem

All Packages  Class Hierarchy  This Package  Previous  Next  Index