Package org.zkoss.zk.ui.sys

Interface DesktopCtrl

All Known Implementing Classes:

DesktopImpl

public interface DesktopCtrl

An addition interface to Desktop for implementation.

Note: applications shall never access this interface.

Author:

tomyeh

Method Summary

Modifier and Type	Method	Description
boolean	activateServerPush(long timeout)	Activates the current thread for accessing this desktop by the server push.
void	addComponent(Component comp)	Adds a component to this page.
void	addPage(Page page)	Adds a page to this desktop.
void	afterComponentAttached(Component comp, Page page)	Invokes UiLifeCycle.afterComponentAttached(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.Page).
void	afterComponentDetached(Component comp, Page prevpage)	Invokes UiLifeCycle.afterComponentDetached(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.Page).
void	afterComponentMoved(Component parent, Component child, Component prevparent)	Invokes UiLifeCycle.afterComponentMoved(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.Component, org.zkoss.zk.ui.Component).
void	afterProcessEvent(Event event)	Invokes EventInterceptor.afterProcessEvent(org.zkoss.zk.ui.event.Event) registered by Desktop.addListener(java.lang.Object).
Event	beforePostEvent(Event event)	Invokes EventInterceptor.beforePostEvent(org.zkoss.zk.ui.event.Event) registered by Desktop.addListener(java.lang.Object).
Event	beforeProcessEvent(Event event)	Invokes EventInterceptor.beforeProcessEvent(org.zkoss.zk.ui.event.Event) registered by Desktop.addListener(java.lang.Object).
Event	beforeSendEvent(Event event)	Invokes EventInterceptor.beforeSendEvent(org.zkoss.zk.ui.event.Event) registered by Desktop.addListener(java.lang.Object).
boolean	ceaseSuspendedThread(EventProcessingThread evtthd, String cause)	Ceases the specified event thread.
void	deactivateServerPush()	Deactivates the thread that has invoked activateServerPush(long) successfully.
void	destroy()	Called when the desktop is about to be destroyed.
boolean	enableServerPush(boolean enable, Serializable enabler)	Enable/Disable serverpush using reference counting, so that multiple enablers can use the same serverpush and deregister whenever they want.
boolean	enableServerPush(ServerPush serverpush)	Enables the server-push feature with the specified server-push controller.
Object	getActivationLock()	Returns the lock used to activate an execution.
org.zkoss.util.media.Media	getDownloadMedia(String medId, boolean reserved)	Returns the media that is associated with Desktop.getDownloadMediaURI(org.zkoss.util.media.Media, java.lang.String), or null if not found.
Object	getLastResponse(String reqId)	Returns the response for the last request, or null if no response yet, or the specified request ID doesn't match the last one (passed to responseSent(java.lang.String, java.lang.Object)).
int	getNextKey()	Returns the next available key which is unique in the whole desktop.
String	getNextUuid(Component comp)	Returns the next available UUID for a component.
String	getNextUuid(Page page)	Returns the next available UUID for a page.
RequestQueue	getRequestQueue()	Returns the request queue.
int	getResponseId(boolean advance)	Returns the sequence ID of the response.
ServerPush	getServerPush()	Returns the server-push controller, or null if it is not enabled yet.
Collection<EventProcessingThread>	getSuspendedThreads()	Returns a collection of suspended event processing threads, or empty if no suspended thread at all.
Visualizer	getVisualizer()	Returns the visualizer associated with this desktop.
void	invokeDesktopCleanups()	Invokes DesktopCleanup.cleanup(org.zkoss.zk.ui.Desktop) for each relevant listener registered by Desktop.addListener(java.lang.Object).
void	invokeExecutionCleanups(Execution exec, Execution parent, List<Throwable> errs)	Invokes ExecutionCleanup.cleanup(org.zkoss.zk.ui.Execution, org.zkoss.zk.ui.Execution, java.util.List<java.lang.Throwable>) for each relevant listener registered by Desktop.addListener(java.lang.Object).
void	invokeExecutionInits(Execution exec, Execution parent)	Invokes ExecutionInit.init(org.zkoss.zk.ui.Execution, org.zkoss.zk.ui.Execution) for each relevant listener registered by Desktop.addListener(java.lang.Object).
Component	mapComponent(String uuid, Component comp)	Maps a component associated with the given UUID to this page.
void	onPiggyback()	Called each time when ZK Update Engine retrieves events.
void	onPiggybackListened(Component comp, boolean listen)	Called when a component added or removed a listener for Events.ON_PIGGYBACK.
List<AuResponse>	piggyResponse(Collection<AuResponse> response, boolean reset)	Adds the responses to the so-called piggy-back queue.
void	recoverDidFail(Throwable ex)	Called when the recovering failed.
void	recycle()	Called when the desktop has been recycled.
boolean	removeComponent(Component comp)	Removes a component to this page.
void	removePage(Page page)	Removes a page from this desktop.
void	responseSent(String reqId, Object resInfo)	Called when ZK Update Engine has sent a response to the client.
boolean	scheduledServerPush()	Returns if there is any scheduled task for server push.
<T extends Event> void	scheduleServerPush(EventListener<T> task, T event)	Schedules a task to run under the server push of the given desktop asynchronously.
void	service(AuRequest request, boolean everError)	Processes an AU request.
void	sessionDidActivate(Session sess)	Notification that the session, which owns this desktop, has just been activated (a.k.a., deserialized) by the Web container.
void	sessionWillPassivate(Session sess)	Notification that the session, which owns this desktop, is about to be passivated (a.k.a., serialized) by the Web container.
void	setExecution(Execution exec)	Sets the execution (used to represent a lock).
void	setId(String id)	Sets the desktop identifier.
void	setResponseId(int resId)	Sets the sequence ID of the response.
void	setVisualizer(Visualizer uv)	Sets the visualizer associated with is desktop.

Method Details

getRequestQueue

RequestQueue getRequestQueue()

Returns the request queue.

getNextKey

int getNextKey()

Returns the next available key which is unique in the whole desktop.

getNextUuid

String getNextUuid(Page page)

Returns the next available UUID for a page. The returned UUID is unique in the desktop. You can consider it as unique in the whole session, though it may not be true if RawId is used (developer's responsibility to avoid conflict), integer overflow (too many UUID in one session, which can be considered as impossible), or a custom ID generator (IdGenerator) is used.

Since:

5.0.3

getNextUuid

String getNextUuid(Component comp)

Returns the next available UUID for a component. The returned UUID is unique in the desktop. You can consider it as unique in the whole session, though it may not be true if RawId is used (developer's responsibility to avoid conflict), integer overflow (too many UUID in one session, which can be considered as impossible), or a custom ID generator (IdGenerator) is used.

Since:

5.0.3

addComponent

void addComponent(Component comp)

Adds a component to this page.

It is used internally and developers shall not invoke it explicityly.

Throws:

InternalError - if there is a component associated with the same UUID

mapComponent

Component mapComponent(String uuid,
 Component comp)

Maps a component associated with the given UUID to this page. Notice that the given uuid can be different from comp's UUID (Component.getUuid()).

If the given component is null, the mapping of UUID is removed.

Unlike addComponent(org.zkoss.zk.ui.Component) and removeComponent(org.zkoss.zk.ui.Component), this method simply replaces the mapping if the given UUID is already mapped to the other component.

It is used internally and developers shall not invoke it explicitly.

Parameters:

comp - the component to associate with the given UUID. If not, the association (i.e., mapping) is removed.

Returns:

the previous component that was associated with the given UUID.

Since:

6.0.0

removeComponent

boolean removeComponent(Component comp)

Removes a component to this page.

It is used internally and developers shall not invoke it explicitly.

Returns:

false always since 10.0.0 (Deprecated: whether UUID is recycled. If true, the caller shall reset UUID of the give component.)

Since:

5.0.4

addPage

void addPage(Page page)

Adds a page to this desktop. It must be called when a page is created.

This is one of the only few method you could access before activating an execution.

removePage

void removePage(Page page)

Removes a page from this desktop.

NOTE: once a page is removed, you can NOT add it back. You shall just GC it.

setId

void setId(String id)

Sets the desktop identifier.

It is callable only if it is the recovering phase, i.e., ExecutionCtrl.isRecovering() is true. In other words, callable only in the invocation of FailoverManager.recover(org.zkoss.zk.ui.Session, org.zkoss.zk.ui.Execution, org.zkoss.zk.ui.Desktop).

Throws:

IllegalStateException - if it is NOT in recovering.

recoverDidFail

void recoverDidFail(Throwable ex)

Called when the recovering failed.

sessionWillPassivate

void sessionWillPassivate(Session sess)

Notification that the session, which owns this desktop, is about to be passivated (a.k.a., serialized) by the Web container.

sessionDidActivate

void sessionDidActivate(Session sess)

Notification that the session, which owns this desktop, has just been activated (a.k.a., deserialized) by the Web container.

destroy

void destroy()

Called when the desktop is about to be destroyed.

recycle

void recycle()

Called when the desktop has been recycled. More precisely, it is called when the desktop is no longer used and ready to be re-used later.

Since:

5.0.7

getSuspendedThreads

Collection<EventProcessingThread> getSuspendedThreads()

Returns a collection of suspended event processing threads, or empty if no suspended thread at all.

An event processing thread is an instance of EventProcessingThread

Note: if you access this method NOT in an event listener for the SAME desktop, you have to synchronize the iteration (though the returned collection is synchronized). Of course, it is always safe to test whether it is empty (Collection.isEmpty()).

        //Use the following pattern IF it is not in the SAME desktop's listener
        Collection c = otherDesktop.getSuspendedThreads();
        if (c.isEmpty()) {
        //do something accordingly
        } else {
        synchronized (c) {
        for (Iterator it = c.iterator(); it.hasNext();) {
          //...
        }
        }
        }

ceaseSuspendedThread

boolean ceaseSuspendedThread(EventProcessingThread evtthd,
 String cause)

Ceases the specified event thread.

Parameters:

cause - an arbitrary text to describe the cause. It will be the message of the thrown InterruptedException.

Returns:

true if the event processing thread is ceased successfully; false if no such thread or it is not suspended.

getDownloadMedia

org.zkoss.util.media.Media getDownloadMedia(String medId,
 boolean reserved)

Returns the media that is associated with Desktop.getDownloadMediaURI(org.zkoss.util.media.Media, java.lang.String), or null if not found.

This method is used internally. Developers rarely need to access this method.

Parameters:

reserved - reserved for future use.

Returns:

the media or null if not found.

onPiggybackListened

void onPiggybackListened(Component comp,
 boolean listen)

Called when a component added or removed a listener for Events.ON_PIGGYBACK.

The implementation usually uses it to optimize whether to call the listener when onPiggyback() is called.

Parameters:

comp - the component that adds an listener for Events.ON_PIGGYBACK. The component may or may not be a root component.

listen - whether the listener is added (or removed).

Since:

3.0.0

onPiggyback

void onPiggyback()

Called each time when ZK Update Engine retrieves events. It is used to implement the piggyback feature by posting the events (see Events.ON_PIGGYBACK). The implementation could post events here. It should not process event here (since event thread might be used).

Used only internally. Application developers shall not call it.

Since:

3.0.0

getServerPush

ServerPush getServerPush()

Returns the server-push controller, or null if it is not enabled yet.

enableServerPush

boolean enableServerPush(ServerPush serverpush)

Enables the server-push feature with the specified server-push controller. If you want to use the default serverpush, use Desktop.enableServerPush(boolean) instead. This method allows the caller to provide a server push for more control.

Example:

desktop.enableServerPush(new PollingServerPush(1000,6000,5));

Notice: a server push controller can be used in one desktop. It cannot be shared.

Parameters:

serverpush - the server-push controller. If null, the server-push feature is disabled (for this desktop). Note: this method will invoke ServerPush.start(org.zkoss.zk.ui.Desktop), so the caller doesn't need to do it.

Since:

3.0.0

See Also:

• Desktop.enableServerPush(boolean)

enableServerPush

boolean enableServerPush(boolean enable,
 Serializable enabler)

Enable/Disable serverpush using reference counting, so that multiple enablers can use the same serverpush and deregister whenever they want.

Parameters:

enable - true/false enable/disable serverpush

enabler - the same reference must be used to disable again

Returns:

Currently only used by DesktopEventQueue to enable several eventqueues to use the same ServerPush

Since:

6.5.4

beforeSendEvent

Event beforeSendEvent(Event event)

Invokes EventInterceptor.beforeSendEvent(org.zkoss.zk.ui.event.Event) registered by Desktop.addListener(java.lang.Object).

Note: it invokes Configuration.beforeSendEvent(org.zkoss.zk.ui.event.Event) automatically.

Since:

3.0.0

beforePostEvent

Event beforePostEvent(Event event)

Invokes EventInterceptor.beforePostEvent(org.zkoss.zk.ui.event.Event) registered by Desktop.addListener(java.lang.Object).

Note: it invokes Configuration.beforePostEvent(org.zkoss.zk.ui.event.Event) automatically.

Since:

3.0.0

beforeProcessEvent

Event beforeProcessEvent(Event event)
                  throws Exception

Invokes EventInterceptor.beforeProcessEvent(org.zkoss.zk.ui.event.Event) registered by Desktop.addListener(java.lang.Object).

Note: it invokes Configuration.beforeProcessEvent(org.zkoss.zk.ui.event.Event) automatically.

Throws:

Exception

Since:

3.0.0

afterProcessEvent

void afterProcessEvent(Event event)
                throws Exception

Invokes EventInterceptor.afterProcessEvent(org.zkoss.zk.ui.event.Event) registered by Desktop.addListener(java.lang.Object).

Note: it invokes Configuration.afterProcessEvent(org.zkoss.zk.ui.event.Event) automatically.

Throws:

Exception

Since:

3.0.0

invokeDesktopCleanups

void invokeDesktopCleanups()

Invokes DesktopCleanup.cleanup(org.zkoss.zk.ui.Desktop) for each relevant listener registered by Desktop.addListener(java.lang.Object).

Used only internally.

It never throws an exception.

Since:

3.0.6

invokeExecutionInits

void invokeExecutionInits(Execution exec,
 Execution parent)
                   throws UiException

Invokes ExecutionInit.init(org.zkoss.zk.ui.Execution, org.zkoss.zk.ui.Execution) for each relevant listener registered by Desktop.addListener(java.lang.Object).

Used only internally.

Parameters:

exec - the execution that is created

parent - the previous execution, or null if no previous at all

Throws:

UiException - to prevent an execution from being created

Since:

3.0.6

invokeExecutionCleanups

void invokeExecutionCleanups(Execution exec,
 Execution parent,
 List<Throwable> errs)

Invokes ExecutionCleanup.cleanup(org.zkoss.zk.ui.Execution, org.zkoss.zk.ui.Execution, java.util.List<java.lang.Throwable>) for each relevant listener registered by Desktop.addListener(java.lang.Object).

Used only internally.

It never throws an exception but logs and adds it to the errs argument, if not null.

Parameters:

exec - the execution that is being destroyed

parent - the previous execution, or null if no previous at all

errs - a list of exceptions (java.lang.Throwable) if any exception occurred before this method is called, or null if no exception at all. Note: you can manipulate the list directly to add or clean up exceptions. For example, if exceptions are fixed correctly, you can call errs.clear() such that no error message will be displayed at the client.

Since:

3.0.6

afterComponentAttached

void afterComponentAttached(Component comp,
 Page page)

Invokes UiLifeCycle.afterComponentAttached(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.Page).

Since:

3.0.6

afterComponentDetached

void afterComponentDetached(Component comp,
 Page prevpage)

Invokes UiLifeCycle.afterComponentDetached(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.Page).

Since:

3.0.6

afterComponentMoved

void afterComponentMoved(Component parent,
 Component child,
 Component prevparent)

Invokes UiLifeCycle.afterComponentMoved(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.Component, org.zkoss.zk.ui.Component).

Parameters:

prevparent - the previous parent. If it is the same as comp's Component.getParent(), comp is moved in the same parent.

Since:

3.0.6

responseSent

void responseSent(String reqId,
 Object resInfo)

Called when ZK Update Engine has sent a response to the client.

Parameters:

reqId - the request ID that the response is generated for. Ignore if null.

resInfo - the response. Ignored if reqId is null.

Since:

5.0.0

getLastResponse

Object getLastResponse(String reqId)

Returns the response for the last request, or null if no response yet, or the specified request ID doesn't match the last one (passed to responseSent(java.lang.String, java.lang.Object)).

The return value is the value passed to resInfo when calling responseSent(java.lang.String, java.lang.Object).

Since:

5.0.0

getResponseId

int getResponseId(boolean advance)

Returns the sequence ID of the response. The client and server uses the sequence ID to make sure the responses are processed in the correct order.

The range of the sequence IDs is 1~999.

Parameters:

advance - whether to advance the number before returning. If true, the ID is increased and then returned. If false, the previous value is returned

Since:

3.5.0

setResponseId

void setResponseId(int resId)

Sets the sequence ID of the response.

It is rarely called other than in the recovering mode, i.e., ExecutionCtrl.isRecovering() is true.

Parameters:

resId - a value between 1 and 999. You can reset the ID by passing a non-positive value.

Since:

3.5.0

piggyResponse

List<AuResponse> piggyResponse(Collection<AuResponse> response,
 boolean reset)

Adds the responses to the so-called piggy-back queue. The responses in the piggy-back queue will be sent in the next AU request.

This method is useful for working thread that wants to sent the responses back to the client. A typical example is the Comet-based server push.

Parameters:

response - the responses to be appended to the piggy-back queue.

reset - whether to reset the piggy-back queue after returning the queued responses.

Returns:

all responses in the piggy-back queue, or null if nothing in the queue.

Since:

5.0.0

scheduleServerPush

<T extends Event> void scheduleServerPush(EventListener<T> task,
 T event)

Schedules a task to run under the server push of the given desktop asynchronously. It is called by Executions.schedule(org.zkoss.zk.ui.Desktop, org.zkoss.zk.ui.event.EventListener<T>, T). Don't call it directly.

Like activateServerPush(long) and deactivateServerPush(), this method could be called in any thread, so the implementation of this method has to be safe for concurrent access.

Parameters:

task - the task to execute

event - the event to be passed to the task (i.e., the event listener). It could null or any instance as long as the task recognizes it.

Throws:

IllegalStateException - if the server push is not enabled.

DesktopUnavailableException - if the desktop is removed (when activating).

Since:

5.0.6

scheduledServerPush

boolean scheduledServerPush()

Returns if there is any scheduled task for server push.

Since:

5.0.6

activateServerPush

boolean activateServerPush(long timeout)
                    throws InterruptedException

Activates the current thread for accessing this desktop by the server push. It is called by Executions.activate(org.zkoss.zk.ui.Desktop). Don't call it directly.

Like scheduleServerPush(org.zkoss.zk.ui.event.EventListener<T>, T), this method could be called in any thread, so it has to be safe for concurrent access.

Note: the server push must be enabled first (by use of Desktop.enableServerPush(boolean)).

Parameters:

timeout - the maximum time to wait in milliseconds. Ignored (i.e., never timeout) if non-positive.

Throws:

IllegalStateException - if the server push is not enabled.

InterruptedException

Since:

3.5.2

deactivateServerPush

void deactivateServerPush()

Deactivates the thread that has invoked activateServerPush(long) successfully. It is called by Executions.deactivate(org.zkoss.zk.ui.Desktop). Don't call it directly.

Since:

3.5.2

service

void service(AuRequest request,
 boolean everError)

Processes an AU request. Notice that not only the requests for a desktop but also the requests for any component in the desktop will go thru this method.

To override the default processing, register an AU request service AuService by invoking Desktop.addListener(java.lang.Object).

1. This method first invokes the registered AU request service (AuService) one-by-one, until the first one returns true.
2. If none of them returns true or no AU service at all, it checks if the request is targeting a component (i.e., AuRequest.getComponent() is not null).
3. If it is targeting a component, it invokes ComponentCtrl.service(org.zkoss.zk.au.AuRequest, boolean) to handle the service.
4. If it is not targeting a component (i.e., targeting to this desktop), it handles as follows.
   • It handles the recognized requests, including onBookmarkChange, onURIChange and onClientInfo.
   • If the request is not one of above, it converts the request to an event (by Event.getEvent(org.zkoss.zk.au.AuRequest)) and then posts the event (by Events.postEvent(org.zkoss.zk.ui.event.Event)).

Notice that the registered AU request service (AuService) will be called, no matter the request is targeting a component or a desktop. And, it can 'intercept' or 'filter' it by returning false.

To send responses to the client, use AbstractComponent.smartUpdate(java.lang.String, java.lang.Object), AbstractComponent.response(org.zkoss.zk.au.AuResponse) or Component.invalidate().

If you want to intercept events, you can register a listener implementing EventInterceptor, or overriding afterProcessEvent(org.zkoss.zk.ui.event.Event).

Parameters:

everError - if any error ever occurred before processing this request. In other words, indicates if the previous request causes any exception.

Since:

5.0.0

setExecution

void setExecution(Execution exec)

Sets the execution (used to represent a lock).

Used only to implement UiEngine.

getVisualizer

Visualizer getVisualizer()

Returns the visualizer associated with this desktop.

Used only to implement UiEngine.

Since:

3.6.2

setVisualizer

void setVisualizer(Visualizer uv)

Sets the visualizer associated with is desktop.

Used only to implement UiEngine.

Since:

3.6.2

getActivationLock

Object getActivationLock()

Returns the lock used to activate an execution. Before calling setVisualizer(org.zkoss.zk.ui.sys.Visualizer), this object returned by this method must be locked first.

Used only to implement UiEngine.

Since:

3.6.2