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Re: Annotations and metadata in RIF

From: Jos de Bruijn <debruijn@inf.unibz.it>
Date: Tue, 29 Jan 2008 17:13:02 +0100
Message-ID: <479F508E.6040108@inf.unibz.it>
To: Dave Reynolds <der@hplb.hpl.hp.com>
CC: RIF WG <public-rif-wg@w3.org>
>> == prelude ==
>>
>> We distinguish between two kinds of annotations:
>> 1 annotations which can be ignored for rule set processing (e.g., 
>> author, date, title, natural language description); we call these 
>> annotations *metadata*
>> 2 annotations which cannot be ignored for rule set processing (e.g., 
>> imports, data set references); we call these annotations *attributes* 
>> [this name is not very good; suggestions are welcome]
> 
> I agree we have this distinction at present, and your proposal cleanly 
> separates them.
> 
> [We could choose to only support metadata and move everything else of 
> semantic significance into the language - specifically imports and 
> required datasets. I'm not sure this is the right approach but we should 
> at least consider it.]
> 
> A possible alternative to the name "attributes" might be "processing 
> instructions", not sure I like it but it's the only plausible option 
> that has sprung to mind so far.

I'm not really comfortable with the term "processing instruction".  For 
example, a data set reference is not necessarily a processing 
instruction.

> 
>> Annotations can be written about any rule set or rule.
>>
>> Since metadata can be ignored for rule set processing, we do not 
>> restrict the metadata properties which can be used in any dialect.
> 
> For interoperability purposes I believe we should recommend a core 
> vocabulary for metadata terms. In particular, I think that it will be 
> quite common to want to give rules and rulesets a name, a longer 
> descriptive comment (possibly multi-lingual), author attribution, 
> creation dates and references to external documentation. If people in 
> general use the same vocabulary for these then editors, viewers and 
> other tools will be more functional and practical interoperation often 
> benefits from being able to find things like comments.
> 
> Specifically for these meatadata terms I suggest:
>    rdfs:label
>    rdfs:comment
>    dc:creator
>    dc:date
>    rdfs:seeAlso

I agreed that we can recommend a core vocabulary.  However, I'm not so 
sure whether the RDFS metadata vocabulary is the best way to go. 
Personally, I prefer using Dublin core (e.g. title, description).  To be 
honest, I never understood why RDFS does not simply use of Dublin core.

> 
>> Attribute properties cannot be ignored; in fact, all attribute 
>> properties must be understood by anyone who processes rule sets of a 
>> particular dialect.  Therefore, every dialect has a fixed set of 
>> attributes properties which may be used.
>> Suggested attribute properties for BLD: rif:imports, 
>> rif:requiresDataSet, rif:dataModel (see [1] for a description of the 
>> rif:requiresDataSet and rif:dataModel properties).
>>
>> == Extension of the presentation syntax ==
>>
>> The syntax for rule sets and rules needs to be extended to allow for 
>> rule set and rule identification.  Furthermore, it is convenient to 
>> group annotations together with rule sets and rules. Finally, it is 
>> currently foreseen that rule sets can have both metadata and 
>> attributes, and rules can only have metadata.  We propose the 
>> following modification of the grammar:
>>
>>   Ruleset  ::= ' Ruleset( ' iri? Attribute* Metadata* RULE* ' ) '
>>   Attribute ::= ' Attribute ( ' iri Const ' ) '
>>   Metadata ::= ' Metadata ( ' iri Const ' ) '
>>   RULE     ::= ' Rule( ' iri? Metadata* RuleContent ' ) '
>>   RuleContent ::= ' Forall ' Var+ ' ( ' RULE ' ) ' | Implies | ATOMIC
>>   Implies  ::= ATOMIC ' :- ' CONDITION
>>
>> Metadata properties can be any IRI; each RIF dialect prescribes a 
>> fixed list of attributes properties.
> 
> A nice simple approach but ...
> 
> (1) It would be useful to enable metadata property values to be 
> structured. Specifically the proposal in [1] uses RDF resources and 
> bNodes for this.

I agree.  I think we can simply use turtle syntax.  I will put my 
proposal on a wiki page and update it.

> 
> (2) I would like to have a documented mapping from our metadata syntax 
> to RDF. This would *not* require an implementer to process the metadata 
> as RDF nor be able to understand RDF syntax but would help (a) forestall 
> questions at Last Call on the relationship, (b) allow us to use RDFS as 
> in [1] to document the intended domain/ranges of the metadata 
> properties. This mapping could be informative rather than normative.

Agreed.  I will add this to my proposal.

Best, Jos

> 
>> Neither attributes nor metadata are reflected in the model theory.
>>
>> If it is deemed necessary that arbitrary metadata statements (not only 
>> about rule sets and rules) can be added, the following change could be 
>> made to the Ruleset production:
>>
>>   Ruleset  ::= ' Ruleset( ' iri? Attribute* Metadata* (RULE | 
>> MetadataStatement)* ' ) '
>>   MetadataStatement  ::= ' MetadataStatement ( ' Const iri Const ' ) '
>>
>> == Extension of the XML syntax ==
>>
>> Ruleset(  rs1
>>   Attribute("a1"^^rif:iri "v1"^^rif:iri)
>>   Attribute("a2"^^rif:iri "v2"^^xsd:string)
>>   Metadata("a3"^^rif:iri  "v3"^^xsd:string)
>>   Metadata("a4"^^rif:iri  "v4"^^rif:iri)
>>   Rule( r1
>>     Metadata("a5"^^rif:iri  "v5"^^xsd:string)
>>   ....
>>   )
>> )
>>
>> translates to
>>
>> <Ruleset rif:identifier="rs1">
>>   <Attribute rif:identifier="a1" type="rif:iri">v1</Attribute>
>>   <Attribute rif:identifier="a2" type="xsd:string">v2</Attribute>
>>   <Metadata rif:identifier="a3" type="xsd:string">v3</Metadata>
>>   <Metadata rif:identifier="a4" type="rif:iri">v4</Metadata>
>>   <Rule rif:identifier="r1">
>>     <Metadata rif:identifier="a5" type="xsd:string">v5</Metadata>
>>     ....
>>   </Rule>
>> </Ruleset>
>>
>>
>> best, Jos
>>
>> [1] http://www.w3.org/2005/rules/wg/wiki/Arch/Data_Sets
> 
> 
> Dave

-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
----------------------------------------------
Doubt is not a pleasant condition, but
certainty is absurd.
   - Voltaire


Received on Tuesday, 29 January 2008 16:13:17 GMT

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