Re: [xml-dev] Content Assembly Mechanism (CAM)

[Philippe Poulard <philippe.poulard@sophia.inria.fr>]

rjelliffe@allette.com.au a écrit :
>> could you elaborate on that relax NG + schematron?
>> i can understand that chaining relax validation and schematron
>> processing is definitely possible.
>>
>> but as far as i understand, they are no integration effort between them.

IMHO, Schematron is not intended to be integrated; even if you embed it 
in RelaxNG (as mentioned below by Rick), the embedded part of Schematron 
will be ignored from the host language (each will ignore the other).

For example, consider an XML editor within which the user is invited to 
insert a new element under a <purchase-order>; a schema processor will 
be able to propose the authorized elements, say <item> and <free-item>, 
as indicated by a RelaxNG schema; unfortunately, some additional 
constraints are not expressible with RelaxNG, say "a <free-item> element 
is allowed only if the total amount of the order is more than 500€", so 
they are expressed with Schematron; then the user select <free-item> 
since it is proposed by RelaxNG, but after insertion it will have a 
warning from Schematron: "you are not allowed to insert this element 
because..."

The Active Schema Language (ASL) figures out elegantly this kind of 
issues by computing dynamically content models instead of serving them 
statically. Concretely, it can compute the content model mentioned above 
exactly as it is expressed: "a <purchase-order> is a sequence of 
<item>s, and if the total amount of the order is more than 500€, 
<free-item> is part of the sequence". So simple, so natural.

ASL:
http://ns.inria.fr/active-tags/active-schema/active-schema.html
The engine is available here:
http://reflex.gforge.inria.fr/
You can run various examples here:
http://reflex.gforge.inria.fr/tutorial-schemas.html

It was the topic of my talk at Balisage last year: "Properties of schema 
mashups: dynamicity, semantic, mixins, hyperschemas"
http://www.balisage.net/Proceedings/vol1/html/Poulard01/BalisageVol1-Poulard01.html
The slides:
http://hal.inria.fr/docs/00/32/26/61/ANNEX/Bal2008poul061003.pdf

> 
> Eddie Robertsson's software to embed Schematron rules in RELAX NG has been
> around since about 2001.
> 
> Also both Schematron and RELAX NG are part of ISO DSDL: one
> long-time-coming part of DSDL is a pipelining execution framework, with
> XProc the candidate. The challenge I see with DSDL is not so much to
> integrate RELAX NG and Schematron (why dilute one?)  as to integrate the
> other parts of DSDL with them.
> 
> Cheers
> Rick Jelliffe
> 
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-- 
Cordialement,

               ///
              (. .)
  --------ooO--(_)--Ooo--------
|      Philippe Poulard       |
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  http://reflex.gforge.inria.fr/
        Have the RefleX !