Hi,
this is what we should have as soon as possible if i am tasting the area
here around JavaOne.
What i call ajax rendering is this, a component knows his state (much
more then it did now!!) and if
he sees a change in his request he will print this out as a javascript
statement that will be send to the browser
and executed with eval()
I will get this javascript of the ajax enabled components on a ajax
request after dispatching to the listener first.
(just like a normal doRender after a component listener call)
So what we don't think we want is subclasses every component that we
have now to get ajax rendering on it.
Because then if you want to use a component that you want to tweak or
implement like a link you have to subclass
2 components the normal one or the ajax enabled one.. So you have to
choose at that time what you want..
What we could do is add 3 methods to Component:
1> final public setAjaxRendering(boolean)
2> non final protected createAjaxRenderer() returns a instanceof a yet
to make interface IAjaxRenderer
3> final public getAjaxRenderer() returns the instance that was made by
2 or null..
that interface can or will have the following methods:
render() The render method that is called when it should render itself
through an ajax call
setCssId(String) // this is really needed because if the component
doesn't have a css id then ajax rendering will be disabled
setVisible(boolean) // component.setVisible() will redirect its boolean
to this object if it has ajax rendering because the component must
render itself, but be made non visible at the client side..
setModelValue(Object value) // ajax rendering will cost more. Because we
have to track changes so that we can generate the right javascript
statements on the server to send to the client.
setStyleClass(String) the style it should use (for example an TextField
could have a normal style and a error style (field turns red))
And i think there will be a lot more set methods for all kind of
properties. We just have to figure out how for we want to go..
Component should bne altered a bit:
by it rendering (real rendering) it should look for its Tag's attribute
map and set the cssid to the above implementation of the IAjaxRender because
the css tag is specified in the html (maybe we should be able to
generate or alter them if css tags are in a listview/repeating components)
als the setVisible method should test for the ajaxrenderer and if it is
there it shouldn't set its own visibililty flag but redirect that to the
ajaxrenderer
So that the component will render itself (and then set though some css
class or javascript to non visible) so that we can alter its state
afterwards
(set it visible, set its value)
So when this is in place this happens if a ajax call is coming in:
the event is dispatched.
then all the components are visited and if they have a ajaxrenderer call
render on it.
the components checks if he has changes that he should set to the
browser (like the model value: document.getElementById(cssid).value = xxxx)
what all the components did return is send to the client and with a
simple javascript eval evaluted and everything is updated.
2 things to look for:
1> we must have a javascript generating class that generate above pieces
of code (i already had some prototype checked in)
2> for example that value =xxxx a few lines above... that xxxx what is
that? Normally the value could go through converters/formatters etc.
And how do we get the model object there. how to really test for a
change.....
any comments?
johan
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