org.lsst.ccs.gconsole.agent

Interface AgentStatusListener

All Known Subinterfaces:

MonitorView

All Known Implementing Classes:

AbstractMonitorView1, AbstractMonitorView2, CellTableView, CellView, CompoundView, ConfigView, DefaultView, ImageView, SectionedTableView, TabbedView, TreeTableView, 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 agent, the listener will receive events in the following order:

• connect(event)
• configure(event)
• zero or more statusChanged(event)
• disconnect(event)

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 complete static information on the source agent (including channels dictionary) becomes available for the first time, and when it changes.
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 status 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.

The implementation should return quickly. Any blocking operations should be scheduled on a separate thread.

Parameters:

event - Event.

configure

default void configure(AgentStatusEvent event)

Called when the complete static information on the source agent (including channels dictionary) becomes available for the first time, and when it changes. 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 contain any information on channels status - corresponding methods return empty collections. Since the disconnection event might or might not be triggered by a status message, getMessage() method might return null.

The implementation should return quickly. Any blocking operations should be scheduled on a separate thread.

Parameters:

event - Event.

statusChanged

default void statusChanged(AgentStatusEvent event)

Called on status change.

Parameters:

event - event Event.