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Resolution for issue 2133: Schema-informed Element and Type

From: Carine Bournez <carine@w3.org>
Date: Wed, 29 Oct 2008 13:28:55 -0400
To: public-exi-comments@w3.org
Cc: Yuri Delendik <yury_exi@yahoo.com>
Message-ID: <20081029172855.GN31685@homer.w3.org>


The EXI Working Group has discussed the issue that you raised about
Schema-informed grammars [1].

The XML Schema mapping to EXI grammar terms described in section 8.5.4
[2] is a normative mapping. A conformant EXI decoder must support this
specified mapping, as stated in the conformance section [3]. As noted
in your comment, it is possible to specify mappings from other
schema languages. Requiring all conformant EXI processors to implement the
W3C XML Schema mapping feature will facilitate interoperability, and 
we picked XML Schema because it is a W3C Recommendation. We do not 
intend to make any judgement or preference over various schema languages.
Other mappings might be done by the EXI Working Group (or another
group) in the future but it is not planned at this time. 
For those reasons, as well as since we do not see real semantic benefit by
the changes, we feel that this section is worth staying in the main body of
the specification.

A second part of your comment suggests that we use EXI grammar terms
to describe EXI Options. We will make it clear that the XML schema for
Options is provided for clarity of the specification, and it is not required
for the EXI processors to read an Options schema. Therefore we think
that adding an equivalent EXI grammar, which would be more verbose, is 
not needed.

The last part of your issue is about the use of "strict" mode. The Working
Group believes that the use of the strict vs. non-strict mode is not
equivalent to the use of a different schema. The processor uses the same
schema but handles deviations from that schema when in non-strict mode.
This enables an use case where sender and receiver agrees to a schema,
and still the encoder has a liberty of arbitrarily using "strict" option 
instance-by-instance basis, without pre-agreed schemaID.

If you are not satisfied with this resolution, please let us know as
soon as possible. Thank you.

[2] http://www.w3.org/TR/exi/#informedElemGrammars
[3] http://www.w3.org/TR/exi/#processorConformance

Carine Bournez -+- W3C Europe
Received on Wednesday, 29 October 2008 17:29:05 UTC

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