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From Christopher Oliver <>
Subject Improving the Woody Flowscript API
Date Wed, 28 Jan 2004 19:05:47 GMT
I've just checked in some experimental improvements to the Woody 
Flowscript API and an associated sample. Because the changes are not 
backward compatible I've placed the files in a new package.

The idea is to try to remove the duplication present in the current API 
in two places:

1) The original JavaScript wrapper of the Woody widget exposed very 
limited functionality. As a result someone chose to also expose the Java 
Widget objects directly. The new ScriptableWidget should be able to 
support all of the functionality of the Java objects (and more) allowing 
us to remove this duplication.
2) Since the JavaScript wrapper's of the widgets are full-fledged 
JavaScript objects you can assign additional properties (not found in 
the form definition) to them which can then be accessed in your pipeline 
(e.g. in JXTemplate's). In addition, you can access the widgets 
themselves more easily via this wrapper, i.e. instead of

   #{getWidget(getWidget(form, 'foo'), 'bar'))}

you can do


Therefore I've removed the additional "bizData" argument from showForm() 
(which seemed like an another unnecessary duplication)

Here is a summary:

1) All widgets are fully modelled. Previously leaf-nodes in the widget 
tree were treated as simple values (String, Number, etc). Leaf widgets 
like Field's now have a 'value' property to assign or access their values.
2) Initialization of complex widgets is possible.
3) I added some basic support for event handling (onClick() for Action's 
and onChange() for fields). I know Sylvain intentionally chose not to 
follow this approach (and instead to place the event handlers in the 
form definition) but there is an advantage to having these in the 
flowscript: namely that you have access to the rest of your application 
data there. In addition, using the new API it is quite easy to add and 
remove repeater rows and to set event handlers on them (see the sample).
4) You can programatically set validation errors on widgets, via the 
setValidationError() function.
5) You can set selection lists on widgets via the setSelectionList() 
6) The implementation of showForm() uses a "bookmark" continuation to 
implement the validation loop (instead of a while loop). The sample 
takes advantage of this to implement a multipage form with a back button 
(in a hackish way, but hopefully you'll get the idea).

Here are some of the problems:
1) Locale handling is broken at the moment
2) Event handling seems a bit flaky (not sure why...)
3) I didn't support Choice/Union/Class (because I don't really know how 
to use them yet).
4) I didn't experiment with or test the Binding stuff but just left it 
the same as before.

Note this is not intended to be a final solution, but rather to just to 
spur discussion and hopefully progress toward a better API for Woody.



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