Re: [Bug 12184] Circularity in xs:override

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C. M. Sperberg-McQueen writes:

> On Mar 10, 2011, at 8:38 AM, Henry S. Thompson wrote:
>
>> [Still working on clearing away the underbrush to try to get at the
>> underlying principles]
>> 
>> ...
>> So, a thought experiment.  Instead of converting includes into
>> overrides, why not start by _eliminating_ includes, thereby reducing
>> the complexity of the situation we have to get our heads around, and
>> exploiting our existing understanding of how to manage re-entrancy and
>> circularity in the include graph?
>
> The most obvious initial reason is that include is defined on
> the component level, not the schema document level.
>
> Are you proposing that we change it to operate on the
> schema-document level?
>
> What do we do about processors which use includes to incorporate
> components stored in other forms?

I am confused, as usual (you're fallable, I'm confused, it's chronic :-)

I read 4.2.3 [1] as being very much expressed in terms of schema
documents.  At the information level, as always, but _not_ at the
component level.  For example, [2] says

 1 If *actual value* of the schemaLocation [attribute] successfully
 resolves one or more of the following is true:

   1.1 It resolves to (a fragment of) a resource which is an XML
   document (of type application/xml or text/xml with an XML
   declaration for preference, but this is not required), which in
   turn corresponds to a <schema> element information item in a
   well-formed information set.

   1.2 It resolves to a <schema> element information item in a
   well-formed information set.

and immediately thereafter we see

 "It is not an error for *actual value* of the schemaLocation
 [attribute] to fail to resolve at all, in which case the
 corresponding inclusion must not be performed."

_However_ I agree we don't what to re-open the whole schema assembly
semantics issue if at all possible, so if that's where we're headed, I
agree not to go there.

In any case, the algorithm in the document attached to my message will
actually work regardless, if you replace references to the URI of
the schema document to some other unique identifier for the
corresponding schema component.

ht

[1] http://www.w3.org/XML/Group/2004/06/xmlschema-1/structures.html#compound-schema
[2] http://www.w3.org/XML/Group/2004/06/xmlschema-1/structures.html#src-include
- -- 
       Henry S. Thompson, School of Informatics, University of Edinburgh
      10 Crichton Street, Edinburgh EH8 9AB, SCOTLAND -- (44) 131 650-4440
                Fax: (44) 131 651-1426, e-mail: ht@inf.ed.ac.uk
                       URL: http://www.ltg.ed.ac.uk/~ht/
 [mail from me _always_ has a .sig like this -- mail without it is forged spam]
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Received on Thursday, 10 March 2011 18:32:41 UTC