Package org.a2aproject.sdk.examples.streamlifecycle.server

Class CloseStreamsHook

java.lang.Object

org.a2aproject.sdk.examples.streamlifecycle.server.CloseStreamsHook

All Implemented Interfaces:

TaskStreamLifecycleHook

@ApplicationScoped
@Alternative
@Priority(1)
public class CloseStreamsHook
extends Object
implements TaskStreamLifecycleHook

Demonstrates closing all streams for a task when the subscriber count reaches a threshold.

When 3 subscribers are connected to the same task, this hook calls StreamCloseHandle.closeStreams() to gracefully close all active streams. The agent executor continues running, but disconnected clients can resubscribe later.

Constructor Summary

Constructors

Constructor	Description
CloseStreamsHook()

Method Summary

Modifier and Type	Method	Description
void	onEvent(String taskId, Event event, StreamCloseHandle handle)	Called after an event has been persisted and distributed to all ChildQueues.
void	onSubscribe(String taskId, StreamCloseHandle handle)	Called when a new ChildQueue is created for a task (a client subscribes to the stream).
void	onUnsubscribe(String taskId, StreamCloseHandle handle)	Called when a ChildQueue closes for a task (a client disconnects or streams are closed).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

CloseStreamsHook

public CloseStreamsHook()

Method Details

onSubscribe

public void onSubscribe(String taskId,
 StreamCloseHandle handle)

Description copied from interface: TaskStreamLifecycleHook

Called when a new ChildQueue is created for a task (a client subscribes to the stream).

If this method calls StreamCloseHandle.closeStreams(), the ChildQueue being created will be closed before tap() returns it to the caller. The caller will receive a closed queue whose dequeueEventItem() throws EventQueueClosedException immediately.

Specified by:

onSubscribe in interface TaskStreamLifecycleHook

Parameters:

taskId - the task identifier

handle - handle to close streams and query subscriber count

onUnsubscribe

public void onUnsubscribe(String taskId,
 StreamCloseHandle handle)

Description copied from interface: TaskStreamLifecycleHook

Called when a ChildQueue closes for a task (a client disconnects or streams are closed).

Calling StreamCloseHandle.closeStreams() from within this callback is safe but has no effect — a reentrancy guard prevents recursive iteration over the children list. To close remaining streams in response to an unsubscription, schedule the call asynchronously or handle it in TaskStreamLifecycleHook.onEvent(java.lang.String, org.a2aproject.sdk.spec.Event, org.a2aproject.sdk.server.events.StreamCloseHandle).

Specified by:

onUnsubscribe in interface TaskStreamLifecycleHook

Parameters:

taskId - the task identifier

handle - handle to close streams and query subscriber count

onEvent

public void onEvent(String taskId,
 Event event,
 StreamCloseHandle handle)

Description copied from interface: TaskStreamLifecycleHook

Called after an event has been persisted and distributed to all ChildQueues.

Specified by:

onEvent in interface TaskStreamLifecycleHook

Parameters:

taskId - the task identifier

event - the event that was processed

handle - handle to close streams and query subscriber count