ZK Developer's Guide

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Chapter 1
It depends on the component whether an event is supported or not. It's noteworthy
to say that an event is sent after the content of the component is updated.
ZUML – ZK User Interface Markup Language
The first thing a new ZK developer is confronted with is the ZUML (ZK User
Interface Markup Language). It's noteworthy to say that this is not a new proprietary
language; it's just an XML with namespace.
There are at least three namespaces that are important for working with ZK:
http://www.zkoss.org/2005/zul The XUL component set
http://www.w3.org/1999/xhtml The XHTML component set
http://www.zkoss.org/2005/zk ZK-specific attributes
Inside a ZUML page, we can use for example: EL expressions, Java, JavaScript, Ruby,
and Groovy.
Where is the session?
In some situations it could be faster to place some zscripts into the page,
and for that we may want to access the session or some other object (for
example the page itself).
In such situations there are some implicit objects that can be
accessed in the pages. The objects are: self, spaceOwner,
page, desktop, session, componentScope, spaceScope,
pageScope, desktopScope, sessionScope, applicationScope,
requestScope, arg, each, forEachStatus, and event.
You can use these objects in a zscript block, or in an element ().
If you need information about the current execution you could use the org.
zkoss.zk.ui.Execution interface. If you are in a component use getDesktop().
getExecution(). When you don't have any component reference use the static
method, getCurrent() from the class org.zkoss.zk.ui.Executions. After this
introduction to ZUML, we present some important points in ZUML.