Martin, Thx. Next time I'll scroll. :-)
Since Example #2 is verbose and Example #3 is the preferred way (using rdf:ID), why do we include Example #2 - just to make the triples explicit? 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: Martin Nally/Raleigh/IBM@IBMUS To: Arthur Ryman <[email protected]> Cc: [email protected], [email protected] Date: 12/06/2010 06:24 PM Subject: Re: [oslc-core] Bug in the core spec Yes, we know this. The spec already includes exactly the syntax you suggest, further down the page - if you had read further you would have seen it. Best regards, Martin Martin Nally, IBM Fellow CTO and VP, IBM Rational tel: +1 (714)472-2690 From: Arthur Ryman <[email protected]> To: Martin Nally/Raleigh/IBM@IBMUS Cc: [email protected], [email protected] Date: 12/06/2010 12:18 PM Subject: Re: [oslc-core] Bug in the core spec Martin/Dave, FYI, RDF.XML also has an abbreviation for reifying statements. You put rdf:ID on the predicate of the Statement and this expands to the usual four triples (Statement, subject, predicate, object). You can then explicitly add more triples about the Statement. I think that this use of rdf:ID makes the document more readable since it identifies the Statement at its point of definition. The alternate of explicity reifying the Statement is more verbose. Also, it's easier to find the unreified Statement if you want to understand its context. The example becomes the following which produces exactly the same set of triples as Martin's corrected example: <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:ID="n1" rdf:resource=" http://example.com/magazines/Field_and_Stream"; /> </terms:Customer> <terms:Customer rdf:about="http://example.com/customers/4321";> <terms:subscribesTo rdf:ID="n2" rdf:resource=" http://example.com/magazines/Cat_Fancy"; /> </terms:Customer> <rdf:Description rdf:about="#n1"> <terms:expirationDate>2010-06-03</terms:expirationDate> <terms:annualPriceUSD>23.95</terms:annualPriceUSD> <terms:delivery rdf:resource=" http://example.com/terms/online"; /> </rdf:Description> <rdf:Description rdf:about="#n2"> <terms:expirationDate>2010-01-22</terms:expirationDate> <terms:annualPriceUSD>15.95</terms:annualPriceUSD> <terms:delivery rdf:resource=" http://example.com/terms/mail"; /> </rdf:Description> </rdf:RDF> 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: Martin Nally <[email protected]> To: [email protected] Date: 12/05/2010 01:43 AM Subject: [oslc-core] Bug in the core spec Sent by: [email protected] I noticed a bug in the core spec (http://open-services.net/bin/view/Main/OslcCoreSpecAppendixLinks). It contains the following XML <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> <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> I believe the lines that begin with <rdf:Statement about="" are wrong. About is used to specify the subject of a group of triples. The empty string is a relative URL, relative to the base. Since no explicit base has been provided, this means the implicit base provided by the enclosing document. Both of the Statement XML elements are thus providing RDF information about the document this RDF is found in. This XML asserts that the enclosing document is an RDF Statement (twice), and also specifies two different subjects, two different objects and two different predicates for it, along with some other properties. I believe the intention was that the statements be blank nodes, or possibly resources with fragment identifiers in their URLs. Since the next example, using rdf:id, creates URLs with fragment identifiers, the better fix might be the following: <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="#n1"> <terms:expirationDate>2010-06-03</terms:expirationDate> <terms:annualPriceUSD>23.95</terms:annualPriceUSD> <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="#n2"> <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> These are still relative URLs, so the URLs of the new statements are <enclosing document URL>#ns1 and <enclosing document URL>#ns2. Best regards, Martin Martin Nally, IBM Fellow CTO and VP, IBM Rational tel: +1 (714)472-2690 _______________________________________________ Oslc-Core mailing list [email protected] http://open-services.net/mailman/listinfo/oslc-core_open-services.net
