I resolved this issue. I captured it as issue #19 in the RDF/XML section: http://open-services.net/bin/view/Main/OslcCoreV1Issues
I added added OSLC Core spec text that specifies the scheme you proposed: http://open-services.net/bin/view/Main/OSLCCoreSpecDRAFT#Three_options_for_RDF_XML For those catching up: the basic idea is this: OSLC specs can allow either abbreviated RDF/XML, full RTDF/XML or both forms and use content-negotiation to determine what is returned. This will allow specs to require abbreviated RDF/XML now and later add full RDF/XML without breaking clients. The new spec text describes these three options, how content negotiation works and how to do abbreviated RDF/XML with Jena. This shouldn't change anything for provider implementations, but XML-only consumers will need to know to ask for application/xml or risk breakage later. As always feedback is most welcome. Thanks, - Dave On Fri, Jul 9, 2010 at 1:36 PM, Arthur Ryman <[email protected]> wrote: > Dave, > > Seems like we are making good progress. Here are the points we need to > settle. > > 1. Be more formal about the OSLC subset so that RDF folks can easily > generate it e.g. using RDF/XML-ABBREV rules, and so XML processors can > create more robust code. > 2. Use HTTP content negotiation to differentiate between full W3C RDF/XML > and the OSLC subset. > > 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 > Twitter | Facebook | YouTube > > > > > > > > From: > Dave <[email protected]> > To: > [email protected] > Date: > 07/09/2010 11:18 AM > Subject: > Re: [oslc-core] Meeting notes and using rdf:RDF as root element > Sent by: > [email protected] > > > > Arthur, this is starting to sound pretty good and it addresses my main > concern with the RDF/XML subset approach, which is: what do we do if > sometime in the future we decide to allow full RDF/XML? > > With your approach, clients that want the subset ask for it with > application/xml and that will always work no matter what we decide to > return for application/rdf+xml > > - Dave > > > On Fri, Jul 9, 2010 at 9:15 AM, Arthur Ryman <[email protected]> wrote: >> >> I suggest that the "correct" way to serve each community is to: >> 1. not alter the meaning of application/rdf+xml, and >> 2. allow domains to define "real" XML formats and use application/xml > for >> them. We could regard the OSLC RDF/XML subset as a "default" >> application/xml representation. >> >> We can handle this situation satisfactorily through standard HTTP > content >> negotiation. Let's confine the discussion to the XML-based >> representations. Here are the principles: >> >> 1. Use application/rdf+xml for content that conforms to the W3C RDF/XML >> standard, without any restrictions >> 2. Use application/xml for content that is well-formed W3C XML. A > special >> case of this is an XML document that starts with <rdf:RDF> and conforms > to >> the OSLC RDF/XML subset. >> 3. If a consumer (client or service) cannot process W3C RDF/XML, then it >> MUST NOT use application/rdf+xml in its HTTP Accept header. >> 4. If a provider (client or service) cannot generate OSLC RDF/XML, then > it >> MUST NOT return application/xml content. >> >> Here are the cases: >> 1. The client can process incoming W3C RDF/XML. This is the maximally >> interoperable case since OSLC RDF/XML is a subset of W3C RDF/XML. The >> client sends >> >> Accept: application/rdf+xml >> >> The server can return either OSLC RDF/XML or W3C RDF/XML and gives it >> >> Content-type: application/rdf+xml. >> >> 2. The client can only process incoming OSLC RDF/XML. The client sends >> >> Accept: application/xml >> >> If the server can generate OSLC RDF/XML then it returns it >> >> Content-type: application/xml >> >> Otherwise the server responds with >> >> 406 Not Acceptable. >> >> -------- >> >> Instead of using application/xml as sugested above, another way to > handle >> this is to use the quality indicator on the Accept header. The quality >> indicator (from 0 to 1) says how well the client can process the media >> type. Since OSLC RDF/XML is valid W3C RDF/XML, we could assign a quality >> level to it, e.g. 0.5. The way to indicate that you can process only > the >> OSLC subset of RDF/XML would be: >> >> Accept: application/rdf+xml; q=0.5 >> >> The OSLC subset would then use >> >> Content-type: application/rdf+xml >> >> 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 >> Twitter | Facebook | YouTube >> >> >> >> >> >> >> >> From: >> Jim des Rivieres/Ottawa/IBM@IBMCA >> To: >> [email protected] >> Date: >> 07/08/2010 05:34 PM >> Subject: >> Re: [oslc-core] Meeting notes and using rdf:RDF as root element >> Sent by: >> [email protected] >> >> >> >> Arthur, >> >>> The OSLC subset and generation rules result in RDF/XML documents that >> are a subset of all possible valid RDF/XML documents. >> >>> If we supported full RDF/XML I wouldn't need to spend time on the >> syntactic details. >> >> This is quite deliberate. If OSLC swallows RDF whole, we end up in a >> position where everyone consuming and providing OSLC domain specs will >> only be able to do so using full-fledged RDF/XML parsers. No consumer >> would ever be able to parse a resource with a regular XML parser, or use >> simple XML tools like xpath to extract a couple of values of interest. >> >> This is explained in >> > http://open-services.net/bin/view/Main/OSLCCoreSpecDRAFT#OSLC_Defined_Resource_Representa > >> >> Here's the relevant passage: >> >> RDF/XML defines an extensive set of XML elements and attributes for >> representing an RDF data model. RDF/XML provides a lot of flexibility > and >> if we allowed each OSLC workgroup to decide now to serialize OSLC >> resources to and from RDF/XML, we would require each workgroup to master >> RDF-XML, we would end-up with different serializations for each domain, >> the XML produced would not be XML-tool friendly and in the end >> interoperability would suffer. >> >> To ensure that the RDF/XML produced by OSLC services is uniform, easy to >> understand and as simple as possible, we define a set of step-by-step >> rules for generating the RDF/XML. We use a very limited set of RDF >> elements and attributes, the rdf:type element and attributes rdf:about, >> rdf:resource= and =rdf:nodeID. >> >> I, for one, think this was the right direction for OSLC Core to go. >> >> Regards, >> >> Jim des Rivieres >> Rational AMC Technical Lead >> >> ----- Forwarded by Jim des Rivieres/Ottawa/IBM on 07/08/2010 04:17 PM >> ----- >> >> From: >> Arthur Ryman/Toronto/IBM@IBMCA >> To: >> Steve K Speicher <[email protected]> >> Cc: >> oslc-core <[email protected]>, >> [email protected] >> Date: >> 07/08/2010 03:46 PM >> Subject: >> Re: [oslc-core] Meeting notes and using rdf:RDF as root element >> Sent by: >> [email protected] >> >> >> >> Steve, >> >> I am not referring to the use of <rdf:RDF> element since that is a part > of >> >> >> RDF/XML. I am referring to the exclusion of those features of RDF/XML > that >> >> >> are not part of the OSLC subset. The OSLC subset and generation rules >> result in RDF/XML documents that are a subset of all possible valid >> RDF/XML documents. There is no guarantee that when I serialize an RDF >> graph using some toolkit that the result will fall within the subset >> defined by OSLC. >> >> For example, the document might contain multiple <rdf:Description> >> elements for the subject nodes instead of "inlining" the triples under >> some main subject node, or a subject node might not use the expected >> rdf:type abbreviation if it had multiple types. There are other > features, >> such as rdf:parseType="Resource" and rdf:parseType="Collection" that are >> not in the OSLC subset, but that might get generated. Those are simply >> abbreviations that produce more compact and readable documents, but that >> are not in the OSLC subset. A serializer could generate them. >> >> On a related thought, consider the issue of "enforcing" conformance to > the >> >> >> OSLC subset. >> >> Currently, the OSLC subset is described implicitly, i.e. as the result > of >> applying the representation rules. This means there is no programmatic > way >> >> >> to check conformance of an RDF/XML document with the OSLC rules. > However, >> I don't think it would be a good use of our time to create an OSLC >> validator. We don't want to enshrine this subset since it's very likely > to >> >> >> change (and probably coincide with RDF/XML eventually). >> >> Here's a real-world example. Today I reviewed a design for calendar >> events, based on the RDF representation of the iCal standard. Here's a >> sample RDF/XML representation: >> >> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"; >> xmlns:jc="http://jazz.net/xmlns/prod/jazz/calendar#"; xmlns=" >> http://www.w3.org/2002/12/cal/icaltzd#"; >> xmlns:foaf="http://xmlns.com/foaf/0.1/";> >> <VCalendar> >> <jc:calendar_owner rdf:parseType="Resource"> >> <foaf:mbox rdf:resource="mailto:[email protected]"; > /> >> <foaf:nick>user</foaf:nick> >> </jc:calendar_owner> >> <component> >> <Vevent> >> <jc:ownerResource > rdf:parseType="Resource" >>> >> <foaf:nick>user</foaf:nick> >> </jc:ownerResource> >> <dtstart rdf:datatype=" >> http://www.w3.org/2002/12/cal/icaltzd#dateTime";>2010-01-01T09:00:00Z</ >> dtstart> >> <dtend rdf:datatype=" >> http://www.w3.org/2002/12/cal/icaltzd#dateTime";>2010-03-31T18:00:00Z</ >> dtend> >> <transp>TRANSPARENT</transp> >> <rrule rdf:parseType="Resource"> >> <freq>WEEKLY</freq> >> <byday>MO,TU,WE,TH,FR</byday> >> </rrule> >> </Vevent> >> </component> >> </VCalendar> >> </rdf:RDF> >> >> This is valid RDF/XML. It uses standards like iCal and FOAF. However, it >> is invalid wrt to OSLC subset. Note the use of rdf:parseType="Resource". >> Also note the use of the iCal dateTime datatype, which is not on the >> approved list of datatypes. I don't think it's a good use of anyone's >> time to try to hammer this into a shape that matches the OSCL subset. > I'd >> rather just focus on the data and interface. If we supported full > RDF/XML >> I wouldn't need to spend time on the syntactic details. >> >> 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 >> Twitter | Facebook | YouTube >> >> >> >> >> >> >> >> From: >> Steve K Speicher <[email protected]> >> To: >> Dave <[email protected]> >> Cc: >> oslc-core <[email protected]> >> Date: >> 07/08/2010 02:39 PM >> Subject: >> Re: [oslc-core] Meeting notes and using rdf:RDF as root element >> Sent by: >> [email protected] >> >> >> >>> > Furthermore, when I try to generate RDF using >>> > the toolkit, it will not conform to the OSLC subset so I'll have to >> write >>> > my own serializer. We are therefore in the paradoxical situation of >>> > embracing RDF as our data model yet making life more difficult for >>> > implementers that want to use RDF toolkits. >>> >>> This could be a real issue and probably warrants some testing with >>> Jena and other RDF serializers. Can anybody comment in this issue? >>> >> >> I inquired on this to a team that I know has been using RDF/XML (Jena) > for >> >> >> >> some time, they said they didn't have this issue. In fact, they had to > do >> >> >> >> some unnatural acts to remove <rdf:RDF> root element, so adding that > back >> has made things much simpler. >> >> - Steve >> >> >> _______________________________________________ >> 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 >> >> >> >> _______________________________________________ >> 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 >> > > _______________________________________________ > Oslc-Core mailing list > [email protected] > http://open-services.net/mailman/listinfo/oslc-core_open-services.net > > > >
