Asynchronous Tasks"

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Notice that <javadoc method="schedule(org.zkoss.zk.ui.Desktop, org.zkoss.zk.ui.event.EventListener, org.zkoss.zk.ui.event.Event)">org.zkoss.zk.ui.Executions</javadoc> can be called anywhere, including another event listener or a working thread. In other words, you don't have to fork a working thread to use this feature.
 
Notice that <javadoc method="schedule(org.zkoss.zk.ui.Desktop, org.zkoss.zk.ui.event.EventListener, org.zkoss.zk.ui.event.Event)">org.zkoss.zk.ui.Executions</javadoc> can be called anywhere, including another event listener or a working thread. In other words, you don't have to fork a working thread to use this feature.
  
Notice that, since there is at most one thread to access the UI of a given desktop, the event listener's performance shall be good. If you have a long operation to do, you could use [[ZK_Developer's_Reference/Event_Handling/Event_Queues#Asynchronous_Event_Listener|event queue's asynchronous event listener]], or implement it as [[ZK Developer's Reference/Server Push/Synchronous Tasks|a synchronous task]] and handle lengthy operation outside of the activation block.
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Notice that, since there is at most one thread to access the UI of a given desktop, the event listener's performance shall be good. Otherwise, it will block other event listeners from execution. Thus, if you have a long operation to do, you could use [[ZK_Developer's_Reference/Event_Handling/Event_Queues#Asynchronous_Event_Listener|event queue's asynchronous event listener]], or implement it as [[ZK Developer's Reference/Server Push/Synchronous Tasks|a synchronous task]] and handle lengthy operation outside of the activation block.
  
 
=Version History=
 
=Version History=

Revision as of 09:14, 2 December 2010


Asynchronous Tasks


If the task of updating UI can be represented as a method, the push can be done easily. All you need to do is

  1. Implement the UI updates in an event listener (implementing EventListener or SerializableEventListener).
  2. Then, schedule it for executed asynchronously by use of Executions.schedule(Desktop, EventListener, Event).

Here is the pseudo code:

Executions.schedule(desktop,
    new EventListener() {
        public void onEvent(Event event) {
            updateUI(); //whatever you like
        }
    }, event);

You could manipulate UI whatever you want in EventListener.onEvent(Event). It is no different from any other event listener.

Notice that Executions.schedule(Desktop, EventListener, Event) can be called anywhere, including another event listener or a working thread. In other words, you don't have to fork a working thread to use this feature.

Notice that, since there is at most one thread to access the UI of a given desktop, the event listener's performance shall be good. Otherwise, it will block other event listeners from execution. Thus, if you have a long operation to do, you could use event queue's asynchronous event listener, or implement it as a synchronous task and handle lengthy operation outside of the activation block.

Version History

Last Update : 2010/12/02


Version Date Content
5.0.6 November 2010 This feature was introduced. With 5.0.5 or prior, you have to use Event Queues or Synchronous Tasks.



Last Update : 2010/12/02

Copyright © Potix Corporation. This article is licensed under GNU Free Documentation License.