Re: [e4-dev] how to contribute to toolkit model ?

[yves.yang@xxxxxxxxxxx]

Hi Mingjian,

XWT relies on a model defined by IMetaclass. At the low level, XWT is
mapped to SWT/JFace by default. You can change the mapping by replacing
the metaclass. For instance, you have a button:

  <Button text=""/>

By default, it is mapped org.eclipse.swt.widget.Button. You can override
it by your own Button: org.custom.Button.

XML isn't humain readable than JSON. But it is good for model-to-model
transformation. XAML tries to keep it as more readable as possible.

The difference between JSON and XML is the extensibility. With JSON, you
have a parser, which is hard to extend. With XML, it is very easy. You
need just to add a new namespace. We use this concept to handle the CSS:

<Composite xmlns="http://www.eclipse.org/xwt/presentation";
	xmlns:x="http://www.eclipse.org/xwt";
	xmlns:css="http://www.eclipse.org/css";>
	<Composite.layout>
		<GridLayout numColumns="3" />
	</Composite.layout>

	<Label text="General" css:id="SeparatorLabel" />
</Composite>

The CSS speficication is handled by a CSS engine. You can define your
namspace handler.

Regards
yves
> Hi, Yves,
>
> I understand your viewpoint. I hand your idea of "separation between
> concept
> and implementation". And your works at e4 0.9 new features are pretty
> nice.
> For the name of "XWT", I guess it is XML-based? However, the strong
> binding
> UI to XML is not very suitable. One advantage of EMF is that EMF defined
> in
> a higher level, and then the way persistence of EMF could be changed to
> anything if someone like.
>
> For instance, (assumed) I like JSON or Google protocol buffers more than
> XML. Did XWT provide this kind of implementation?(or say, is there a full
> "separation between concept and implementation" for XWT?). If XWT can give
> me this choice, I think it is acceptable as well:)
>
>
> ps: I am not familiar with the XWT, If I am wrong, correct me:)
>
> best regards,
> Jin
>
>
> 2009/9/2 <yves.yang@xxxxxxxxxxx>
>
>> Hi Jin,
>>
>> A declarative UI is very important for e4 to simple UI development for
>> enterprise SI presentation. It provides a separation between concept and
>> implementation, and unify all UI frameworks and data frameworks
>> (including
>> EMF) to work together. It should be the foundation of eclipse for all UI
>> Tools such as VE, MDA like PMF/EGF. So the standardization of
>> declarative
>> UI in e4 is absolutly necessary for the success of e4.
>>
>> Without this standard, it will be a masse. We are already in this
>> situation in Java. There are XUL, Xform, XSWT and others, but no
>> standard.
>> Who dare to use it? Which tool support it?
>>
>> Best regards
>> Yves YANG
>> > EMF seem higher level technology than XML. EMF provide many advanced
>> tools
>> > to solve the actual world's problem. A XML file is a data aggregation.
>> > But,
>> > it is simple to understand. However  parsing many XMLs or one big XML
>> is
>> > not
>> > lightweight absolutely. And so I don't much like the idea of "XML
>> > Everywhere". But, One question is that, is it possible to make all
>> > additional technologies as the options for e4? we don't need be forced
>> to
>> > choose one specific technology?
>> > best regards,
>> > Jin Mingjian
>> > _______________________________________________
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>> >
>>
>>
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