Re: [xml-dev] RE: Caution using XML Schema backward- or forward-compatib

["Stephen Green" <stephengreenubl@gmail.com>]

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@gmail.com> 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@googlemail.com> 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@gmail.com> 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
> > >
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> >
>
>
> --
> 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