[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: RE: Caution using XML Schema backward- or forward-compatib
Interestingly this already exists. I easily found it with a search on OWL WSDL http://www.daml.org/services/owl-s/1.0/owl-s-wsdl.html http://www.daml.org/services/owl-s/1.0/ OWL-S On 04/01/2008, Stephen Green <stephengreenubl@g...> wrote: > I'm thinking of something along either of these lines: > Plan (A): > Just as there are advocates of dual purpose urls for semantic web > - a single url which the server detects as being called by human or > by machine and returns either the human-readable content or the > machine-readable metadata (e.g. RDF/S) accordingly, so I would > envisage a special case, perhaps, for WSDL. There might be an > HTTP header attribute, say, that says 'give me WSDL' and another > which say (perhaps in the same header) 'I can also understand > RDF/S' (or OWL-DS or OWL-Lite, say). The semantically equipped > server might return WSDL (or even SOAP at runtime) along with, > perhaps in the HTTP header (until WSDL/SOAP acquire the right > semantics, say), a pointer to a semantic metadata resource or > somehow the resource itself. That resource might be like this > > RDF/S classes and properties > RDF/S descriptions - perhaps 'graphs' of endpoint + XPath + metadata > - perhaps a pointer to or inclusion of Schematron > or OWL or genericode (for, say, code values) > With some kind of profile or ontology limiting all this for web service > capabilities (perhaps one for WSDL/design time and another for SOAP > /runtime) similar order of complexity to Dublin Core, say, it should > be (am I wrong?) feasible to have tools detect semantic changes > such as the addition of a new code value so the consuming software > 'knows' to look out for it or throw an error if it can't handle new codes. > Phew! Sorry for long sentences (no time for shorter ones!). > > Plan (B): use BPSS with CPPA - ingredients already there in standards > - just add software. > > In both cases, I don't know enough about it but maybe a semantic > reasoner is needed. So combine knowledgebase and WS software > and some kind of profile and special stuff on servers for HTTP. > > Plan (C): find something like this but doable now, e.g. just using > WSDL + SOAP + XML Schema + Schematron and some codelists > defined in Schematron with a way to interpret new code values (like > UBL proposes) without breaking anything (using XSLT to trim stuff > not understood too). > > Plan (D): extend both WSDL and SOAP to include a url to a particular > type of RDF or OWL or Schematron metadata file > (e.g. with codes/values) which can be updated at any time without > new schema or new url - where updates can be detected by equipped > consumer software if need be and exceptions or appropriate action > taken. > > On 04/01/2008, Fraser Goffin <goffinf@g...> wrote: > > > - each specifying within the WSDL the meaning of the distance > > > > What mechanism in WSDL are you expecting to be able to define semantics ? > > > > Accepting the idea that it might be possible to define schemata that > > provide sufficient meta-data to ensure that semantics are [less] > > ambiguous (i.e. your idea that the introduction of the 'method' > > attribute') is fair enough, but we also need to consider the case that > > Michael [Kay] outlined, that of 'semantic drift'. An information item > > that starts out with one purpose and over time drifts into other uses, > > and of course that very often we don't create a perfect schema in > > version 1.0 with all future needs catered for :-) > > > > As far as the approach of creating a new URL for what in some cases > > should be considered as minor revision changes (note: I don't include > > a semantic change as one of those), I agree, this seems to be an > > un-necessary overhead. Thats why I prefer to categorize changes as > > breaking and non-breaking where non-breaking should provide at least > > backwards compatibility and ideally forwards as well. > > > > Fraser. > > > > On 04/01/2008, Stephen Green <stephengreenubl@g...> wrote: > > > > Not using a codelist but using a method attribute seems to solve > > > > the problem with no need for new url. That seems to be the key. > > > > Add metadata everywhere in version 1. I still wonder: Is RDF/S > > > > going to be a valid way to do this? Would it work? It does seem > > > > to be becoming the standard way to add metadata for semantics. > > > > > > > P.S. > > > > > > With example > > > <distance>100</distance> > > > what meaning does this have? If it isn't clear what distance is meant > > > then maybe there is a need for *two* new web services: > > > - each specifying within the WSDL the meaning of the distance > > > - one for the first meaning and another for the second > > > - both being a distinct improvement on the first > > > - the original being preserved for consumer compatibility where > > > an attribute like 'method' might break the WSDL consumers > > > This just isn't likely to happen though because there might be > > > all sorts of similarly vague elements throughout the WSDL, each > > > perhaps needing new versions at some point - and a new url > > > or several new urls for each case just doesn't seem acceptable. > > > > > > Maybe if the attribute was not added in the first place then there > > > is a way to add the metadata it would have contained in another > > > way which doesn't break the WSDL consumers. The missing > > > piece seems to me to be 'tool support'. > > > > > > Maybe if OWL were used to add the metadata (as an afterthought > > > if an attribute like 'method' was missed from version 1) there might > > > be a way for a change in such metadata to trigger a signal in the > > > web service consumer. Perhaps that needs to be added to tools > > > and maybe standardization is needed too. I would love to be on the > > > committee deciding what to call any possible extension of WSDL > > > or combination of WSDL and OWL say - maybe there is a way > > > to call it WSDL-OWL and switch letters to make it WS-LD-OWL, > > > pronounced 'wise-old-owl' :-) > > > > > > I don't know enough about WSDL but when working with ebXML > > > I asked for an attribute 'externalDocumentDefRef' to be added to > > > ebXML BPSS. This, were there the tool support, could perhaps > > > allow a pointer to semantic metadata to be linked to a web service > > > via CPP/A and ebBP definitions. I would think tools would have to > > > detect any changes in the metadata and signal that something has > > > to be looked into as a thrown exception (fatal or otherwise). So > > > with the right ingredients in the web service, it is possible for > > > semantic changes to be automatically picked up by suitable tools. > > > > > > -- > > > Stephen Green > > > > > > Partner > > > SystML, http://www.systml.co.uk > > > Tel: +44 (0) 117 9541606 > > > > > > http://www.biblegateway.com/passage/?search=matthew+22:37 .. and voice > > > > > > _______________________________________________________________________ > > > > > > XML-DEV is a publicly archived, unmoderated list hosted by OASIS > > > to support XML implementation and development. To minimize > > > spam in the archives, you must subscribe before posting. > > > > > > [Un]Subscribe/change address: http://www.oasis-open.org/mlmanage/ > > > Or unsubscribe: xml-dev-unsubscribe@l... > > > subscribe: xml-dev-subscribe@l... > > > List archive: http://lists.xml.org/archives/xml-dev/ > > > List Guidelines: http://www.oasis-open.org/maillists/guidelines.php > > > > > > > > > > > -- > Stephen Green > > Partner > SystML, http://www.systml.co.uk > Tel: +44 (0) 117 9541606 > > http://www.biblegateway.com/passage/?search=matthew+22:37 .. and voice > -- Stephen D. Green Partner SystML, http://www.systml.co.uk Tel: +44 (0) 117 9541606 http://www.biblegateway.com/passage/?search=matthew+22:37 .. and voice
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