[jsdl-wg] Proposed Extension draft document

[Michel Drescher]

Donal K. Fellows wrote:
> Michel Drescher wrote:
>> here's a write-up of the parameter sweep extension.
>>
>> If possible, I'd like to have a discussion about it on the upcoming call.
> 
> A few comments.
> 
>  It's possible to structure the Assignment stuff so that the xsi:type
>  arguments may be omitted. The key is that you have to declare elements
>  and a substitution group as well. Given that, there's no ambiguity in
>  the resulting documents and tooling like Axis does the right thing,
>  generating an inheritance hierarchy.

Yes I know. Both alternatives -- abstract types and substitutionGroups 
-- are functionally equivalent. So whichever fits best current tooling 
(the draft is in quite early stage, though) should be used in the 
extension. I have no preference, really.

On the other hand, the substitutionGroup technique requires you to 
define a default assignment function. I think there is no default 
assignment function that would be applicable here.

>  Your example (Appendix 2) omits required SweepGroup elements. This
>  leads me to ask which is actually definitive about your proposal; the
>  example or the schema/spec.

Actually, it doesn't. I tried to write the draft proposal in the style 
of element information sets, but I obviously failed. ;-)
In fact, the schema came into existence first; I hacked the document 
yesterday -- which seem quite obvious regarding the language used. ;-)

Hence the example does not omit the SweepGroup element -- "SweepGroup" 
is an XML Schema group that does not render element start and end tags.
Again, if tooling does not support that very well if at all, it is a 
matter of seconds to change that to a plain old contain er element.

>  It would be nice to be able to attach some kind of way of restricting
>  the space being swept; I might want to sweep an even grid of points
>  excepting omitting a few where I know there are singularities (e.g. the
>  origin, a fairly common case!)

I think I know what you mean. Let's talk about it (and have some schema 
fun?) today at FLE.

>  Will it be possible to sweep over non-string content (e.g. element
>  content)? Like this, it would be easy to sweep over, say, EPRs...

The "Parameter" element's value is a XPath expression. So it may 
evaluate to an attribute's value or element value. If the assignment 
function is chosen wisely, then it yields strings that contain XML 
snippets. This way, you can sweep over EPRs...


As I said, the draft proposal is in a fairly early stage. While this 
implies a nice amount of work yet uncompleted it also has nice 
opportunities, like "plug in your use case here!(TM)" ;-)

Cheers,
Michel

-- 
Michel <dot> Drescher <at> uk <dot> fujitsu <dot> com
Fujitsu Laboratories of Europe
+44 20 8606 4834