org.lsst.ccs.gconsole.services.aggregator

Interface AgentStatusListener

All Known Subinterfaces:

MonitorView, PersistableMonitorView

All Known Implementing Classes:

AbstractMonitorView, CellTableView, CellView, ComboGroupView, CompoundView, ConfigurationView, ConfigView, DefaultView, GroupView, ImageView, LazyTreeView, SectionedTableView, SummaryTableView, TabbedGroupView, TabbedView, TreeView

public interface AgentStatusListener

Classes that implement this interface can be registered with AgentStatusAggregator to receive notifications when an agent connects or disconnects from the buses, or when there are changes in data channels published by one of the connected agents. Typically, a listener is registered with an AgentChannelsFilter or with explicit sets of agents and channels to limit events that trigger notifications. See AgentStatusAggregator for details on how the notifications are filtered. Note that due to asynchronous nature of communication over the buses, agents are not guaranteed to remain in the reported state by the time listeners are notified.

For every remote agent, the listener will receive events in the following order:

• connect(event) - when the agent is first seen on the buses.
• configure(event) - when the agent is OPERATIONAL, and all its dictionaries are available.
• zero or more statusChanged(event) - whenever the data this listener is interested in changes.
• disconnect(event) - when the agent disconnects from the buses or goes into OFFLINE state.

This sequence may be interrupted if the listener is removed from the status aggregator.

All methods are called consecutively on a dedicated thread. Implementations of these methods should return quickly. Any time consuming or potentially blocking operations should be scheduled on separate threads.

Empty default implementations are provided for all methods.

Author:

onoprien

Method Summary

Modifier and Type	Method and Description
default void	configure(AgentStatusEvent event) Called when the source agent reaches OPERATIONAL state and its all static information (including channels dictionary) becomes available.
default void	connect(AgentStatusEvent event) Called when a new agent connects to the buses.
default void	disconnect(AgentStatusEvent event) Called when an agent disconnects from the buses or goes into OFFLINE state.
default void	statusChanged(AgentStatusEvent event) Called on data change.

Method Detail

connect

default void connect(AgentStatusEvent event)

Called when a new agent connects to the buses. Newly registered listeners are notified immediately if the agent is already connected.

The event passed to this method does not contain any information on channels (corresponding methods return empty collections) or a reference to a status message. The event can only be used to retrieve AgentInfo descriptor and a reference to the AgentStatusAggregator instance.

Parameters:

event - Event.

configure

default void configure(AgentStatusEvent event)

Called when the source agent reaches OPERATIONAL state and its all static information (including channels dictionary) becomes available. Newly registered listeners are notified immediately if the information is already available.

The event passed to this method contains a list of added channels. Methods accessing lists of changed and removed channels will return empty collections. Since the configuration event is not necessarily triggered by a status message, getMessage() method returns null.

Parameters:

event - Event.

disconnect

default void disconnect(AgentStatusEvent event)

Called when an agent disconnects from the buses or goes into OFFLINE state.

The event passed to this method does not have any added or modified channels, but all previously existing channels are listed as removed. Since the disconnection event might or might not be triggered by a status message, getMessage() method might return null.

Parameters:

event - Event.

statusChanged

default void statusChanged(AgentStatusEvent event)

Called on data change.

Parameters:

event - event Event.