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Re: XML Schemata for RIF-FLD

From: Chris Welty <cawelty@gmail.com>
Date: Fri, 28 Aug 2009 09:41:34 -0400
Message-ID: <4A97DE8E.3050101@gmail.com>
To: Nick Bassiliades <nbassili@csd.auth.gr>
CC: public-rif-comments@w3.org
Nick,

Hi, thanks for the feedback and actually checking the schema.

Nick Bassiliades wrote:
 > Hi,
 >
 > I would like to congratulate the WG for a thorough and careful work
 > on defining a rule standard for the web. It is important that the
 > current standard is based on previous attempts, such as RuleML, so
 > that interoperability with existing systems/prototypes is maintained.
 >
 > Mostly, I would like to comment on the XML Schema for RIF-FLD (this may
 > be present on other RIF-related Schemata; I didn't check).
 >
 > Specifically, in the FLDSkyline.xsd file there are two lines:
 >
 >    <xs:include schemaLocation="FLDBaseline.xsd"/>
 >    <xs:redefine schemaLocation="FLDBaseline.xsd">
 >
 > which actually should not co-exist, because xs:redefine implies that an
 > external schema file is included, but some of the definitions in there
 > are redefined. As a consequence, the above XML Schema file does not
 > validate in e.g. XMLSpy. Actually, only the redefine is needed.

Thanks for catching this bug. While it validated in XSV, there were warnings. We 
thus dropped the xs:include and merged the two xs:redefine's in v. 1.4 of 
FLDSkyline.xsd (http://www.w3.org/2005/rules/wiki/FLD#Skyline_Schema_Module).

 > Furthermore, I would like to remark that currently the XML Schema
 > definitions for various elements are not opted for modularity and
 > extensibility. For example, the definition of the element "Implies"
 > encapsulates its complex data type, not allowing for redefinition by an
 > extension of FLD.
 >
 > For example, I'm working on a defeasible logic extension of RIF-FLD,
 > where I would like to add some attributes to indicate the rule type
 > (strict, defeasible, defeater). However, since the complexType of
 > "Implies" is not named, I cannot redefine it, including an attribute list.
 >
 > I believe that since RIF is supposed to be a family of languages,
 > extending one another, this extensibility should be taken into account
 > for the XML Schemata.

The current XML Schema started with two top-level modules (FLDBaseline.xsd and 
FLDSkyline.xsd). Further modularization, possibly including the fine-grained 
modularity you are proposing, is a topic of upcoming efforts.

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-The RIF WG
Received on Friday, 28 August 2009 13:42:16 GMT

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