Small Talks/2012/December/New Features of ZK 6.5.1

Author
Timothy Clare, Potix Corporation

Date
December 4, 2012

Version
ZK 6.5.1

The Default Command for MVVM

• Available for ZK:
• 

ZK 6.5.1 brings a default command for MVVM. When a binder receives a command, it starts to find ViewModel's command methods by matching its name. If the binder cannot find a matched method, it invokes default command method.

Assume that there are only two command methos in the below ViewModel. If we trigger a command "exit", a binder invokes the default command method defaultAction() because it cannot find a command method named "exit".

public class OrderVM {

    @Command
    public void newOrder(){
    ...
    }
  
    @DefaultCommand
    public void defaultAction(){
    ...
    }
}

Control Page visibility with HTML 5 API in ZK

• Available for ZK:
• 

In order to develop power and CPU efficient web applications, W3C publishes a specification named Page Visibility in HTML 5 which defines a means for site developers to programmatically determine the current visibility state of the page. In this specification, there are two attributes defined: hidden and visibilityState, where hidden is a boolean value representing whether the current page is visible or not and visibilityState represents that the current page have four states: hidden, visible, prerender, and unloaded.

In ZK 6.5.1, the API with onVisibilityChange event was implemented which provides the ability to find out when a page is visible or hidden. This has a lot of benefit as it enables saving of CPU cycles as well as bandwidth. The following is a very simple example:

<window title="window" border="normal">
    <attribute name="onVisibilityChange">
        if (!event.isHidden())
            lbl.setValue("Welcome back");
    </attribute>
    <label id="lbl"></label>
</window>

For more information please check the blog post here and the ZK Developer's Reference.

Comet Server push support

• Available for ZK:
• 

The visibility functionality has also been extended to comet server push to reduce the server loading by default.

Download & other resources

• Download ZK 6.5 here
• Take a look at ZK 6.5.1's release notes here

Comments

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