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Re: PROV-ISSUE-493: prov:type has type Value; valid values too general, include number, datetime, boolean, etc. [prov-dm]

From: Curt Tilmes <Curt.Tilmes@nasa.gov>
Date: Wed, 12 Sep 2012 09:27:41 -0400
Message-ID: <50508DCD.20002@nasa.gov>
To: <public-prov-wg@w3.org>
I see your point -- by design the data model itself should be very
general.

Could we leave the DM itself open, but constrain the type of prov:type
within PROV-O and/or PROV-XML?  In translating the examples where
they have free text, we can simply impose a namespace to qualify the
types in the more concrete representations.

Curt

On 09/12/2012 09:22 AM, Luc Moreau wrote:
> Hi Curt and Stephan,
>
> I am less certain about this change.
>
> First, do you mean QName as in xsd:QName?
> Why not use the prov:QualifiedName, which we already have (and can be
> transformed into uris).
>
> But then, why just prov:QualifiedName , and why not URI (xsd:anyURI)?
>
> The reason why this was left unspecified is that PROV, intentionally,
> refrained from defining
> what a type system is, and therefore, a consequence, was that we didn't
> define how to
> represent a given type value.
>
> Luc
>
> On 09/12/2012 01:27 PM, Curt Tilmes wrote:
>>
>> I agree with Stephan.  The real reason for having prov:type at all is
>> to encourage consistency.  Qnames encourage capturing semantic meaning
>> beyond free text.
>>
>> The types we've defined
>>    http://www.w3.org/TR/prov-dm/#term-attribute-type
>> set a precedent for the type of types we think should fill prov:type,
>> and the discussion of prov:type in the extensibility points section:
>>    http://www.w3.org/TR/prov-dm/#extensibility-section
>> shows examples defining new prov:types as qnames in other namespaces.
>>
>> This would require some rework of examples, but I think the change
>> would be valuable in the long term.
>>
>> Curt
>>
>> On 09/12/2012 02:19 AM, Stephan Zednik wrote:
>>> A quick reminder about this issue.
>>>
>>> Looking at the PROV-DM document again I see a few examples where simple
>>> non-qname strings are used for prov:type values.
>>>
>>>   From example 21 (http://www.w3.org/TR/prov-dm/#anexample-communication)
>>>
>>> prov:type="fine paying, check writing, and mailing"
>>>
>>> I think in most if not all of these cases the prov:type value could be
>>> simplified to a qname.
>>>
>>> I understand this change is significant due to the timing of the
>>> suggestion, but I believe the benefit of making this change is
>>> worthwhile.
>>>
>>> Thanks,
>>> --Stephan
>>>
>>> On Sep 4, 2012, at 11:18 AM, Provenance Working Group Issue Tracker
>>> <sysbot+tracker@w3.org <mailto:sysbot+tracker@w3.org>> wrote:
>>>
>>>> PROV-ISSUE-493: prov:type has type Value; valid values too general,
>>>> include number, datetime, boolean, etc. [prov-dm]
>>>>
>>>> http://www.w3.org/2011/prov/track/issues/493
>>>>
>>>> Raised by: Stephan Zednik
>>>> On product: prov-dm
>>>>
>>>> The value of prov:type is a Value
>>>> (http://www.w3.org/TR/prov-dm/#term-value) which has the following
>>>> definition:
>>>>
>>>> A value ◊ is a constant such as a string, number, time, qualified
>>>> name, IRI, and encoded binary data, whose interpretation is outside
>>>> the scope of PROV. Values can occur in attribute-value pairs.
>>>>
>>>> Each kind of such values is called a datatype. Use of the following
>>>> data types is recommended.
>>>>
>>>> The RDF-compatible [RDF-CONCEPTS] types, including those taken from
>>>> the set of XML Schema Datatypes [XMLSCHEMA11-2];
>>>> Qualified names introduced in this specification.
>>>> The normative definitions of these datatypes are provided by their
>>>> respective specifications.
>>>>
>>>> This means that numbers, datetimes, booleans, and unstructured strings
>>>> are valid values of prov:type.  The prov value section on RDF
>>>> compliance also seems to suggest there should be a prov:type datatype
>>>> property in prov-o, which to my knowledge does not currently exist.
>>>>
>>>> So my question is, are we ok with numbers, datetimes, booleans as
>>>> valid values of prov:type?  All of the examples in the DM document
>>>> appear to use qnames for values of prov:type.
>>>>
>>>> Second, is there support for a proposal to restrict values of
>>>> prov:type to qnames?
>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>


-- 
Curt Tilmes, Ph.D.
U.S. Global Change Research Program
1717 Pennsylvania Avenue NW, Suite 250
Washington, D.C. 20006, USA

+1 202-419-3479 (office)
+1 443-987-6228 (cell)
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Received on Wednesday, 12 September 2012 13:28:07 GMT

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