UiEngine (zk 9.5.1.3 API)

All Known Implementing Classes:

UiEngineImpl
```
public interface UiEngine
```
UI engine is responsible to process requests from the client, sends the response back to the client with the assistance of ExecutionCtrl.
ExecutionCtrl encapsulates protocol-dependent codes, such that UiEngine works independent of any protocol (such as HTTP).
Note: each application (a ServletContext in HTTP) has its own UI Engine (Singleton per app).

Author:

tomyeh

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`activate(Execution exec)` Activates an execution such that you can access a component.
`boolean`	`activate(Execution exec, int timeout)` Activates an execution such that you can access a component.
`void`	`addInvalidate(Component comp)` Invalidates a component to cause redrawing.
`void`	`addInvalidate(Page page)` Invalidates the page to cause all of its components to redraw.
`void`	`addMoved(Component comp, Component oldparent, Page oldpg, Page newpg)` Called to update (redraw) a component, when a component is moved.
`void`	`addResponse(AuResponse response)` Adds a response directly by using `AuResponse.getOverrideKey()` as the override key.
`void`	`addResponse(java.lang.String key, AuResponse response)` Adds a response which will be sent to client at the end of the execution.
`void`	`addResponse(java.lang.String key, AuResponse response, int priority)` Adds a response with the given priority.
`void`	`addSmartUpdate(Component comp, java.lang.String attr, java.lang.Object value, boolean append)` Smart-updates a property of the peer widget.
`void`	`addSmartUpdate(Component comp, java.lang.String attr, java.lang.Object value, int priority)` Adds a smart update that will be executed at the given priority.
`void`	`addUuidChanged(Component comp)` Called before changing the component's UUID.
`void`	`beginUpdate(Execution exec)` Activates and prepare for asynchronous update
`boolean`	`ceaseSuspendedThread(Desktop desktop, EventProcessingThread evtthd, java.lang.String cause)` Ceases the specified event thread.
`void`	`closeUpdate(java.lang.Object ctx)` Deactivates the execution and cleans up.
`Component[]`	`createComponents(Execution exec, PageDefinition pagedef, Page page, Component parent, Component insertBefore, VariableResolver resolver, java.util.Map<?,?> arg)` Creates components from the specified page and definition.
`void`	`deactivate(Execution exec)` Deactivates an execution, such that other threads could activate and access components.
`void`	`desktopDestroyed(Desktop desktop)` Called when a desktop is being removed.
`boolean`	`disableClientUpdate(Component comp, boolean disable)` Sets whether to disable the update of the client widget.
`void`	`endUpdate(Execution exec)` Executes posted events, deactivate and ends the asynchronous update.
`void`	`execNewPage(Execution exec, PageDefinition pagedef, Page page, java.io.Writer out)` Creates components specified in the given page definition.
`void`	`execNewPage(Execution exec, Richlet richlet, Page page, java.io.Writer out)` Invoke `Richlet.service(org.zkoss.zk.ui.Page)`, when a new page is creates upon visiting a richlet.
`void`	`execRecover(Execution exec, FailoverManager failover)` Executes the recovering.
`void`	`execUpdate(Execution exec, java.util.List<AuRequest> requests, AuWriter out)` Executes an asynchronous update to a component (or page).
`JSONArray`	`finishUpdate(java.lang.Object ctx)` Finishes the update and returns the result in an array of JSON object.
`java.lang.String`	`getNativeContent(Component comp, java.util.List<NodeInfo> children, Native.Helper helper)` Retrieve the native content for a property of the specified component.
`java.util.Collection<EventProcessingThread>`	`getSuspendedThreads(Desktop desktop)` Returns a collection of suspended event processing threads belonging to the specified desktop, or empty if no suspended thread at all.
`boolean`	`hasSuspendedThread()` Returns if any suspended event processing thread in the whole system.
`boolean`	`isInvalidated(Component comp)` Returns if this component needs to be redrawn.
`void`	`notify(Desktop desktop, java.lang.Object obj)` Wakes up a single event processing thread for the specified desktop that is waiting on the specified object.
`void`	`notify(java.lang.Object obj)` Wakes up a single event processing thread that is waiting on the specified object.
`void`	`notifyAll(Desktop desktop, java.lang.Object obj)` Wakes up all event processing threads for the specified desktop that are waiting on the specified object.
`void`	`notifyAll(java.lang.Object obj)` Wakes up all event processing thread that are waiting on the specified object.
`void`	`recycleDesktop(Execution exec, Page page, java.io.Writer out)` Reuse the desktop and generate the output.
`void`	`sendRedirect(java.lang.String uri, java.lang.String target)` Sends a temporary redirect response to the client using the specified redirect location URL.
`void`	`setAbortingReason(AbortingReason aborting)` Aborts the current execution.
`Component`	`setOwner(Component comp)` Called before a component redraws itself if the component might include another page.
`void`	`start(WebApp wapp)` Starts the engine.
`java.lang.Object`	`startUpdate(Execution exec)` Activates an execution that will allow developers to update the state of components.
`void`	`stop(WebApp wapp)` Stops the engine.
`void`	`wait(java.lang.Object obj)` Suspends the current processing of an event and wait until the other thread invokes `notify(Object)`, `notifyAll(Object)`, `notify(Desktop, Object)` or `notifyAll(Desktop, Object)` for the specified object.

- Method Detail
  - start
```
void start(WebApp wapp)
```
    Starts the engine.
  - stop
```
void stop(WebApp wapp)
```
    Stops the engine. Called only if the server is about to stop.
  - desktopDestroyed
```
void desktopDestroyed(Desktop desktop)
```
    Called when a desktop is being removed.
    Application developers don't need to remove pages and desktops. They are removed and cleaned up automatically.
  - setOwner
```
Component setOwner(Component comp)
```
    Called before a component redraws itself if the component might include another page.
    If a new page is created, the specified component will become the owner of the new page.
    It must reset the owner in the finally clause.
```
old = ue.setOwner(this);
try{
  ...
} finally {
  ue.setOwner(old);
}
```
    Since 5.0.6, the owner must implement Includer.
    Returns:
    
    the previous owner
    
    Since:
    
    5.0.0
  - isInvalidated
```
boolean isInvalidated(Component comp)
```
    Returns if this component needs to be redrawn.
    Note:
    1. It always returns true if the current execution is not an asynchronous update.
    2. If its parent is invalidated, this component will be redrawn too, but this method returns false since addInvalidate(Component) was not called against this component.
    Since:
    
    3.0.5
  - addInvalidate
```
void addInvalidate(Page page)
```
    Invalidates the page to cause all of its components to redraw.
  - addInvalidate
```
void addInvalidate(Component comp)
```
    Invalidates a component to cause redrawing. Called when Component.invalidate() is called.
  - addSmartUpdate
```
void addSmartUpdate(Component comp,
                    java.lang.String attr,
                    java.lang.Object value,
                    boolean append)
```
    Smart-updates a property of the peer widget.
    
    Parameters:
    
    append - whether to append the updates of properties with the same name. If false, only the last value of the same property will be sent to the client.
    
    Since:
    
    5.0.2
  - addSmartUpdate
```
void addSmartUpdate(Component comp,
                    java.lang.String attr,
                    java.lang.Object value,
                    int priority)
```
    Adds a smart update that will be executed at the given priority. The higher priority, the earlier the update is executed. If addSmartUpdate(Component, String, Object, boolean) is invoked, the priority is assumed to 0.
    If the priority is the same, the update is executed in the order of first-in-first out. You rarely need to control the sequence, unless the update is used to instantiate client-side widgets that other updates might depend on. In this case, it is suggested to specify the priority as 10000 (and not to use priority higher than 10000 for other situation).
    
    Since:
    
    6.0.0
  - addResponse
```
void addResponse(AuResponse response)
```
    Adds a response directly by using AuResponse.getOverrideKey() as the override key. In other words, it is the same as addResponse(resposne.getOverrideKey(), response)
    If the response is component-dependent, AuResponse.getDepends() must return a component. And, if the component is removed, the response is removed, too.
    
    Since:
    
    5.0.2
    
    See Also:
    
    addResponse(String, AuResponse)
  - addResponse
```
void addResponse(java.lang.String key,
                 AuResponse response)
```
    Adds a response which will be sent to client at the end of the execution. Called by AbstractComponent.response(org.zkoss.zk.au.AuResponse).
    Note: Execution.addAuResponse(org.zkoss.zk.au.AuResponse) is a shortcut to this method, and it is used by application developers.
    If AuResponse.getDepends() is not null, the response depends on the returned component. In other words, the response is removed if the component is removed. If it is null, the response is component-independent.
    
    Parameters:
    
    key - could be anything. If null, the response is appended. If not null, the second invocation of this method in the same execution with the same key and the same depends (AuResponse.getDepends()) will override the previous one.
    
    See Also:
    
    addResponse(AuResponse)
  - addResponse
```
void addResponse(java.lang.String key,
                 AuResponse response,
                 int priority)
```
    Adds a response with the given priority. The higher priority, the earlier the update is executed. The priority of addResponse(String, AuResponse) and addResponse(AuResponse) is assumed to be 0.
    If the priority is the same, the update is executed in the order of first-in-first out.
    
    Since:
    
    6.0.1
  - addMoved
```
void addMoved(Component comp,
              Component oldparent,
              Page oldpg,
              Page newpg)
```
    Called to update (redraw) a component, when a component is moved. If a component's page or parent is changed, this method need to be called only once for the top one.
    
    Parameters:
    
    oldparent - the parent before moved
    
    oldpg - the page before moved
    
    newpg - the page after moved
  - addUuidChanged
```
void addUuidChanged(Component comp)
```
    Called before changing the component's UUID.
    
    Since:
    
    5.0.3
  - execNewPage
```
void execNewPage(Execution exec,
                 PageDefinition pagedef,
                 Page page,
                 java.io.Writer out)
          throws java.io.IOException
```
    Creates components specified in the given page definition. Called when a new page is creates.
    
    Throws:
    
    java.io.IOException
  - execNewPage
```
void execNewPage(Execution exec,
                 Richlet richlet,
                 Page page,
                 java.io.Writer out)
          throws java.io.IOException
```
    Invoke Richlet.service(org.zkoss.zk.ui.Page), when a new page is creates upon visiting a richlet.
    
    Throws:
    
    java.io.IOException
  - recycleDesktop
```
void recycleDesktop(Execution exec,
                    Page page,
                    java.io.Writer out)
             throws java.io.IOException
```
    Reuse the desktop and generate the output.
    
    Throws:
    
    java.io.IOException
    
    Since:
    
    5.0.0
  - execUpdate
```
void execUpdate(Execution exec,
                java.util.List<AuRequest> requests,
                AuWriter out)
         throws java.io.IOException
```
    Executes an asynchronous update to a component (or page). It is the same as execUpdate(exec, requests, null, out).
    Note: the output must be XML and UTF-8.
    
    Parameters:
    
    requests - a list of AuRequest.
    
    Throws:
    
    java.io.IOException
  - startUpdate
```
java.lang.Object startUpdate(Execution exec)
                      throws java.io.IOException
```
    Activates an execution that will allow developers to update the state of components.
    It is designed to implement Bridge.
    
    Returns:
    
    a context that shall be passed to finishUpdate(java.lang.Object).
    
    Throws:
    
    java.io.IOException
    
    Since:
    
    5.0.5
    
    See Also:
    
    finishUpdate(java.lang.Object), closeUpdate(java.lang.Object)
  - finishUpdate
```
JSONArray finishUpdate(java.lang.Object ctx)
                throws java.io.IOException
```
    Finishes the update and returns the result in an array of JSON object. Notice it does not deactivate the execution. Rather, the caller has to invoke closeUpdate(java.lang.Object).
    It is designed to implement Bridge.
    
    Parameters:
    
    ctx - the context returned by the previous call to startUpdate(org.zkoss.zk.ui.Execution)
    
    Throws:
    
    java.io.IOException
    
    Since:
    
    5.0.5
    
    See Also:
    
    startUpdate(org.zkoss.zk.ui.Execution), closeUpdate(java.lang.Object)
  - closeUpdate
```
void closeUpdate(java.lang.Object ctx)
          throws java.io.IOException
```
    Deactivates the execution and cleans up.
    It is designed to implement Bridge.
    
    Throws:
    
    java.io.IOException
    
    Since:
    
    5.0.5
    
    See Also:
    
    startUpdate(org.zkoss.zk.ui.Execution), finishUpdate(java.lang.Object)
  - execRecover
```
void execRecover(Execution exec,
                 FailoverManager failover)
```
    Executes the recovering.
  - createComponents
```
Component[] createComponents(Execution exec,
                             PageDefinition pagedef,
                             Page page,
                             Component parent,
                             Component insertBefore,
                             VariableResolver resolver,
                             java.util.Map<?,?> arg)
```
    Creates components from the specified page and definition. It can be called when execNewPage(org.zkoss.zk.ui.Execution, org.zkoss.zk.ui.metainfo.PageDefinition, org.zkoss.zk.ui.Page, java.io.Writer) or execUpdate(org.zkoss.zk.ui.Execution, java.util.List<org.zkoss.zk.au.AuRequest>, org.zkoss.zk.au.AuWriter) was called. It assumes the execution is already locked to this desktop.
    Note: if both page and parent are null, the created components don't belong to any page/parent.
    
    Parameters:
    
    exec - the execution (never null).
    
    pagedef - the page definition (never null).
    
    page - the page. Ignored if parent is specified and parent's page is not null (parent's page will be used). If both page and parent are null, the created components won't belong to any page.
    
    parent - the parent component, or null if no parent component. If parent is specified, page is ignored.
    
    insertBefore - the sibling component that new components will be inserted before. Ignored if null (i.e., append as last children).
    
    resolver - the variable resolver used to resolve variables. Ignored if null.
    
    arg - a map of parameters that is accessible by the arg variable in EL, or by Execution.getArg(). Ignored if null.
    
    Returns:
    
    the components being created.
    
    Since:
    
    6.0.0
  - sendRedirect
```
void sendRedirect(java.lang.String uri,
                  java.lang.String target)
```
    Sends a temporary redirect response to the client using the specified redirect location URL.
    After calling this method, the caller shall end the processing immediately (by returning). All pending requests and events will be dropped.
    
    Parameters:
    
    uri - the URI to redirect to, or null to reload the same page
    
    target - the new target, or null to denote the same browser window
  - setAbortingReason
```
void setAbortingReason(AbortingReason aborting)
```
    Aborts the current execution. if not null, it means the current execution is aborting
    Note: if setAbortingReason is ever set with non-null, you CANNOT set it back to null.
    After call this method, you shall not keep processing the page because the rendering is dropped and the client is out-of-sync with the server.
    
    Parameters:
    
    aborting - the aborting reason.
  - wait
```
void wait(java.lang.Object obj)
   throws java.lang.InterruptedException,
          SuspendNotAllowedException
```
    Suspends the current processing of an event and wait until the other thread invokes notify(Object), notifyAll(Object), notify(Desktop, Object) or notifyAll(Desktop, Object) for the specified object.
    It can only be called when the current thread is processing an event. And, when called, the current processing is suspended and ZK continues to process the next event and finally render the result.
    It is typical use to implement a modal dialog where it won't return until the modal dialog ends.
    
    Parameters:
    
    obj - any non-null object to identify what to wait, such that notify(Object) and notify(Desktop, Object) knows which object to notify.
    
    Throws:
    
    UiException - if it is called not during event processing.
    
    SuspendNotAllowedException - if there are too many suspended exceptions. Deployers can control the maximal allowed number of suspended exceptions by specifying max-suspended-thread in zk.xml, or invoking Configuration.setMaxSuspendedThreads(int).
    
    java.lang.InterruptedException
  - notify
```
void notify(java.lang.Object obj)
```
    Wakes up a single event processing thread that is waiting on the specified object.
    Unlike notify(Desktop, Object), this method can be invoked only if the same desktop is locked for processing requests.
    
    Parameters:
    
    obj - any non-null object to identify what to notify. It must be same object passed to wait(java.lang.Object).
    
    Throws:
    
    UiException - if it is called not during event processing.
    
    See Also:
    
    notify(Desktop, Object), notifyAll(Object)
  - notify
```
void notify(Desktop desktop,
            java.lang.Object obj)
```
    Wakes up a single event processing thread for the specified desktop that is waiting on the specified object.
    Unlike notify(Object), this method can be called any time. It is designed to let working threads resume an event processing thread.
    Notice: if this method is NOT called in an event processing thread, the resumed thread won't execute until the next request is received. To enforce it happen, you might use the timer component (found in ZUL).
    
    Parameters:
    
    desktop - the desktop which the suspended thread is processing. It must be the same desktop of the suspended thread.
    
    obj - any non-null object to identify what to notify. It must be same object passed to wait(java.lang.Object).
    
    See Also:
    
    notify(Object), notifyAll(Desktop, Object)
  - notifyAll
```
void notifyAll(java.lang.Object obj)
```
    Wakes up all event processing thread that are waiting on the specified object.
    Unlike notify(Desktop, Object), this method can be invoked only if the same desktop is locked for processing requests.
    
    Parameters:
    
    obj - any non-null object to identify what to notify. It must be same object passed to wait(java.lang.Object).
    
    Throws:
    
    UiException - if it is called not during event processing.
    
    See Also:
    
    notify(Desktop, Object), notifyAll(Object)
  - notifyAll
```
void notifyAll(Desktop desktop,
               java.lang.Object obj)
```
    Wakes up all event processing threads for the specified desktop that are waiting on the specified object.
    Unlike notifyAll(Object), this method can be called any time. It is designed to let working threads resume an event processing thread.
    If this method is NOT called in an event processing thread, the resumed thread won't execute until the next request is received. To enforce it happen, you might use the timer component (found in ZUL).
    
    Parameters:
    
    desktop - the desktop which the suspended thread is processing. It must be the same desktop of the suspended thread.
    
    obj - any non-null object to identify what to notify. It must be same object passed to wait(java.lang.Object).
    
    See Also:
    
    notify(Object), notifyAll(Desktop, Object)
  - activate
```
void activate(Execution exec)
```
    Activates an execution such that you can access a component. You must call deactivate(org.zkoss.zk.ui.Execution) in the finally clause.
    Note: you RARELY need to invoke this method because execNewPage(org.zkoss.zk.ui.Execution, org.zkoss.zk.ui.metainfo.PageDefinition, org.zkoss.zk.ui.Page, java.io.Writer) and execUpdate(org.zkoss.zk.ui.Execution, java.util.List<org.zkoss.zk.au.AuRequest>, org.zkoss.zk.au.AuWriter) will activate and deactivate automatically.
    Note: this method can be called only when processing a client request (e.g., HTTP) other than creating a new page and processing async-update.
    Also, even if you use this method to grant the right to access components of the specified page, don't post events, create, remove, invalidate and do any smart updates. In other words, READ ONLY.
  - activate
```
boolean activate(Execution exec,
                 int timeout)
```
    Activates an execution such that you can access a component. Unlike activate(Execution), you could specify an amount of time (timeout), and it returns false if it takes longer than the given amount of time before granted.
    
    Parameters:
    
    timeout - the number of milliseconds to wait before giving up. It is ignored if negative, i.e., it waits until granted if negative.
    
    Returns:
    
    whether the activation succeeds
    
    Since:
    
    5.0.6
  - deactivate
```
void deactivate(Execution exec)
```
    Deactivates an execution, such that other threads could activate and access components.
  - beginUpdate
```
void beginUpdate(Execution exec)
```
    Activates and prepare for asynchronous update
    
    Since:
    
    3.5.0
  - endUpdate
```
void endUpdate(Execution exec)
        throws java.io.IOException
```
    Executes posted events, deactivate and ends the asynchronous update.
    
    Throws:
    
    java.io.IOException
    
    Since:
    
    5.0.0
  - getNativeContent
```
java.lang.String getNativeContent(Component comp,
                                  java.util.List<NodeInfo> children,
                                  Native.Helper helper)
```
    Retrieve the native content for a property of the specified component. The native content is a value of a property that is represented by a XML fragment (actually NativeInfo).
    Example:
```
<html>
 <attribute name="content">
  <br/>
 </attribute>
</html>
```
    Parameters:
    
    comp - the component that the native content will be assigned to. It is the object that the self variable is assigned when evaluating EL expressions.
    
    children - a list of NativeInfo, TextInfo and others. This method evaluates them one-by-one and returns the result which is the value that will be assigned.
    
    helper - the helper used to generate the content.
    
    Since:
    
    3.5.0
    
    See Also:
    
    Property
  - hasSuspendedThread
```
boolean hasSuspendedThread()
```
    Returns if any suspended event processing thread in the whole system.
  - getSuspendedThreads
```
java.util.Collection<EventProcessingThread> getSuspendedThreads(Desktop desktop)
```
    Returns a collection of suspended event processing threads belonging to the specified desktop, or empty if no suspended thread at all.
    An event processing thread is an instance of EventProcessingThread
    
    Parameters:
    
    desktop - the desktop that the suspended event processing threads belong to (never null).
  - ceaseSuspendedThread
```
boolean ceaseSuspendedThread(Desktop desktop,
                             EventProcessingThread evtthd,
                             java.lang.String cause)
```
    Ceases the specified event thread.
    
    Parameters:
    
    desktop - which desktop the event thread belongs to
    
    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.
  - disableClientUpdate
```
boolean disableClientUpdate(Component comp,
                            boolean disable)
```
    Sets whether to disable the update of the client widget. By default, if a component is attached to a page, modifications that change the visual representation will be sent to the client to ensure the consistency.
    
    Returns:
    
    whether it has been disabled before this invocation, i.e., the previous disable status
    
    Since:
    
    3.6.2

Interface UiEngine

Method Summary

Method Detail

start

stop

desktopDestroyed

setOwner

isInvalidated

addInvalidate

addInvalidate

addSmartUpdate

addSmartUpdate

addResponse

addResponse

addResponse

addMoved

addUuidChanged

execNewPage

execNewPage

recycleDesktop

execUpdate

startUpdate

finishUpdate

closeUpdate

execRecover

createComponents

sendRedirect

setAbortingReason

wait

notify

notify

notifyAll

notifyAll

activate

activate

deactivate

beginUpdate

endUpdate

getNativeContent

hasSuspendedThread

getSuspendedThreads

ceaseSuspendedThread

disableClientUpdate