Dave, I think we need to follow the guidance in the RDF specs about the meaning of reified Statements. The purpose of reification is so that you can make statements about statements, e.g. do you believe a statement, who made the statement, for what time period is the statement valid, etc. [1]
RDF applications sometimes need to describe other RDF statements using RDF, for instance, to record information about when statements were made, who made them, or other similar information (this is sometimes referred to as "provenance" information). Granted that there is no sharp boundary, but the example proposed in the guidance seems to be well on the other side. The example is really about properties of a very natural domain model resource, Subscription, not about the subscribesTo link. [1] http://www.w3.org/TR/rdf-primer/#reification Regards, ___________________________________________________________________________ Arthur Ryman, PhD, DE Chief Architect, Project and Portfolio Management IBM Software, Rational Markham, ON, Canada | Office: 905-413-3077, Cell: 416-939-5063 From: Dave <[email protected]> To: Arthur Ryman/Toronto/IBM@IBMCA Cc: oslc-core <[email protected]>, [email protected] Date: 09/17/2010 01:05 PM Subject: Re: [oslc-core] REMINDER: OSLC Core WG meeting tomorrow 10am US/ET On Fri, Sep 17, 2010 at 11:48 AM, Arthur Ryman <[email protected]> wrote: > Thx for improving the example. But now I find myself asking another > question. Why are we using magazine subscriptions? Because, at the time we came up with the examples, we did not have real domain examples yet. > This example looks technically correct, but it looks very contrived. If I > was designing a data model that involved magazine subscriptions, I would > certainly make a Subscription a first-class resource, and I would define > all the usual properties on it. In this example, somehow we have elevated > the subscribesTo property to a higher importance than the subscription > itself, and we have in effect turned the reified Statement into a > substitute for a Subscription resource. In practice, I would use a > hasSubscription property to relate the Customer to a Subscription. We don't really provide guidance on how you decide whether to model a relationship as an intermediate resource or as a link with property values. Perhaps you must do this on a case-by-case basis but what is the thought process? I assume it is based on use cases and attempting to understand the queries needed to support those use cases. > I think an example should be more than technically correct. It should also > show how a technique is motivated in practice. I have to believe that > there is a more compelling example for the introduction of link > properties. We need a real-world, OSLC domain example where it becomes > natural to add properties to the link. If we can't find a convincing > example, perhaps this link guidance is not needed. I believe we have some real examples now and perhaps we should consider adding them to later editions of this guidance. Thanks, Dave > > Regards, > ___________________________________________________________________________ > > Arthur Ryman, PhD, DE > > Chief Architect, Project and Portfolio Management > IBM Software, Rational > Markham, ON, Canada | Office: 905-413-3077, Cell: 416-939-5063 > > > > > > From: > Dave <[email protected]> > To: > oslc-core <[email protected]> > Date: > 09/16/2010 12:58 PM > Subject: > Re: [oslc-core] REMINDER: OSLC Core WG meeting tomorrow 10am US/ET > Sent by: > [email protected] > > > > Thanks, Jim. That looks much better. I just made the fixes you suggested > in the link guidance. > > re: formatting dates, I think we should handle that in the Representation > Guidance, which perhaps we need to formally finalize as well. > > - Dave > > > > On Wed, Sep 15, 2010 at 2:03 PM, James Conallen <[email protected]> > wrote: > Some quick comments. I think Example #2 should be simplified with: > <rdf:RDF > xmlns:terms="http://example.com/terms/"; > xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";> > > <terms:Customer rdf:about="http://example.com/customers/4321";> > <terms:subscribesTo rdf:resource=" > http://example.com/magazines/Field_and_Stream"; /> > </terms:Customer> > > <terms:Customer rdf:about="http://example.com/customers/4321";> > <terms:subscribesTo rdf:resource="http://example.com/magazines/Cat_Fancy " > /> > </terms:Customer> > > <rdf:Statement rdf:about=""> > <terms:expirationDate>2010-06-03</terms:expirationDate> > <terms:annualPriceUSD>23.95</terms:annualPriceUSD> > <rdf:subject rdf:resource="http://example.com/customers/4321"/> > <terms:delivery rdf:resource="http://example.com/terms/online"; /> > <rdf:subject rdf:resource="http://example.com/customers/4321"/> > <rdf:object rdf:resource="http://example.com/magazines/Field_and_Stream "/> > <rdf:predicate rdf:resource="http://example.com/terms/subscribesTo"; /> > </rdf:Statement> > > <rdf:Statement rdf:about=""> > <terms:expirationDate>2010-01-22</terms:expirationDate> > <terms:annualPriceUSD>15.95</terms:annualPriceUSD> > <terms:delivery rdf:resource="http://example.com/terms/mail"; /> > <rdf:subject rdf:resource="http://example.com/customers/4321"/> > <rdf:object rdf:resource="http://example.com/magazines/Cat_Fancy"/> > <rdf:predicate rdf:resource="http://example.com/terms/subscribesTo"; /> > </rdf:Statement> > > </rdf:RDF> > > Note I corrected the small typo (copy-paste error) with the actual values > for the expiration date and annual price for the Cat Fancy link. Also to > be consistent with the JSON version I corrected the delivery value. > > I think you'll also want to correct in Example #3 the delivery method for > the cat fancy link to mail (to be consistent with JSON representation). > > Finally looking at this example, especially with the JSON format, have we > given any consideration to formatting dates. For example is the first date > June 3rd, or March 6th? In RDF formats we can specify the datetime format > explicitly (i.e. ^^xsd:dateTime ). Not sure about JSON. > > <jim/> > > jim conallen > CAM Lead Architect > [email protected] > Rational Software, IBM Software Group > > > > Dave ---09/15/2010 01:48:38 PM---Minutes have been posted here: > http://open-services.net/bin/view/Main/OslcCoreMeetings20100915 > > From: Dave <[email protected]> > To: oslc-core <[email protected]> > Date: 09/15/2010 01:48 PM > Subject: Re: [oslc-core] REMINDER: OSLC Core WG meeting tomorrow 10am > US/ET > Sent by: [email protected] > > > > > Minutes have been posted here: > http://open-services.net/bin/view/Main/OslcCoreMeetings20100915 > > As always, feedback is most welcome. > > Thanks, > Dave > > > On Tue, Sep 14, 2010 at 8:56 PM, Dave <[email protected]> wrote: >> We will have a Core WG meeting tomorrow Wednesday September 15 at 10AM >> US/ET. Here's the info: >> >> Agenda: >> http://open-services.net/bin/view/Main/OslcCoreMeetings20100915 >> >> If you have additional agenda items, please speak up. >> >> Telecon: >> * Participant passcode: 558663 >> * Toll free: 1-866-423-8350 >> * Toll: 1-719-387-8273 >> >> Online meeting: >> * For people outside IBM >> https://www.lotuslive.com/join?schedid=4446009 >> * For IBM employees >> https://wedc.lotus.com/meeting/join/?schedid=4446009 > >> (IBM intranet authentication required) >> >> Thanks, >> Dave >> > > _______________________________________________ > Oslc-Core mailing list > [email protected] > http://open-services.net/mailman/listinfo/oslc-core_open-services.net > > _______________________________________________ > Oslc-Core mailing list > [email protected] > http://open-services.net/mailman/listinfo/oslc-core_open-services.net > > > >
