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Re: schemaMapping issues breakdown (issue 6)

From: Jacek Kopecky <jacek.kopecky@deri.org>
Date: Mon, 05 Jun 2006 17:49:28 +0200
To: verma@cs.uga.edu
Cc: Rama Akkiraju <akkiraju@us.ibm.com>, public-ws-semann@w3.org
Message-Id: <1149522568.3834.17.camel@localhost>

Hi Kunal, 

I'd say that information necessary for both upcasting and downcasting
(what we call lifting and lowering in WSMO grounding [1]) should be in
the same place.

There is potentially an m:n mapping between various schemata and various
ontologies - data from one ontology can be expressed in various
schemata, and the meaning of one schema can be described by various
ontologies. Each of these links between a single ontology and a single
schema has to describe both directions for data mapping, so we should
put everything in a similar place in SA-WSDL.

Best regards,

Jacek

[1] http://www.wsmo.org/TR/d24/d24.2/v0.1/

On Tue, 2006-05-30 at 15:57 -0400, Kunal Verma wrote:
> Rama,
> 
> We may not have explicity stated it in the paper, but the inherent
> assumption is that schemaMapping is used to store both upcast and
> downcast. From a SAWSDL perspective, you could think of two attributes
> - schemaMapping.upCast and schemaMapping.downCast or some better way
> of achieving this.
> 
> I know that having mapping both ways adds more complexity to the
> spec., but as you correctly pointed out, ontologies are not a good
> place either, so there may be no other option.
> 
> Thanks,
> Kunal
> 
> On 5/30/06, Rama Akkiraju <akkiraju@us.ibm.com> wrote:
> >
> > Kunal,
> >
> > In the paper you referenced below, you talk about upcasting and
> > downcasting. Upcasting information is stored in the WSDL. Where would
> > downcasting information be stored? In the ontology? If so, how can we
> > burden an ontology to have pointers to elements in individual WSDLs? there
> > could many such WSDLs that may need downcasting. By this, may be you are
> > inferring that the concepts in the ontology have to updated to accommodate
> > enough information abou the terms used in WSDLs that are being matched. Is
> > this right? I am just guessing here. Can you please clarify where the
> > downcasting information be stored in your work?
> >
> > Thank you.
> >
> > Regards
> > Rama Akkiraju
> >
> >
> >
> >
> >
> >              "Kunal Verma"
> >              <verma@cs.uga.edu
> >              >                                                          To
> >              Sent by:                  "Jacek Kopecky"
> >              public-ws-semann-         <jacek.kopecky@deri.org>,
> >              request@w3.org            public-ws-semann@w3.org
> >                                                                         cc
> >
> >              05/29/2006 01:45                                      Subject
> >              PM                        Re: schemaMapping issues breakdown
> >                                        (issue 6)
> >
> >              Please respond to
> >              verma@cs.uga.edu
> >
> >
> >
> >
> >
> >
> >
> > Hi all,
> >
> > We worked on this issue when we were writing the WSDL-S spec. I agree with
> > Jacek's comments (especially option 1c). Comments are inline.
> >
> >   Hi all,
> >
> >   here's an attempt to break down what I think are the separate issues in
> >
> >   clarifying schemaMapping (issue 6 [1]). This email is written with my
> >   chair hat off. 8-)
> >
> >   I assume that schemaMapping attribute points to a document that
> >
> >
> >   specifies a transformation. It seems that there are two orthogonal sets
> >
> >   of options that we need to consider. Wherever I use RDF below I mean any
> >   ontological data language (can be RDF, WSML or any such language of
> >
> >
> >   choice).
> >
> >   1) The transformation is a) between an XML Schema on one side and an
> >
> >   ontology on the other side (schema-level mapping) or b) between XML
> >   document conforming to the XML Schema on one side and RDF data that uses
> >
> >
> >   some ontology on the other side (data-level, runtime mapping).
> >
> >
> >   I believe option a) above is not useful because the XML Schema in WSDL
> >   is given and static, the transformation is as static, so the result is
> >
> >   also static, and therefore it can be saved somewhere and pointed to
> >   using modelReference, as opposed to requiring the processor to take the
> >   schema, run the transformation, and arrive at the same result every
> >   time.
> >
> >   herefore I assume 1b for the formulation and discussion of the
> >
> >
> >
> >   following aspect:
> >
> >   2) The transformation goes a) from XML to RDF, b) from RDF to XML, or
> >   c) both ways.
> >
> >   Since I dismissed the option 1a above, schemaMapping cannot be used
> >   easily for discovery, instead it could be used when a service is
> >
> >
> >
> >   discovered to work with the necessary semantic terms, and then the
> >   client that has instances of those terms wants to invoke the service so
> >   it has to transform between its semantic data and the XML that the
> >
> >
> >   service requires.
> >
> >
> >   I believe that we need to consider both directions because the service
> >   both consumes and produces XML messages, so messages for the service
> >   have to be created from semantic data, and messages from the service
> >
> >
> >
> >   need to be parsed back into semantic data.
> >
> >   Depending on whether SAWSDL wants to enable invocation or only discovery
> >   (and composition, which uses similar data), we may keep or drop
> >   schemaMapping, and if we keep it, we may need to talk about which
> >
> >
> >
> >   directions of the mapping it should handle.
> >
> >   The conclusion is that we have to decide whether we want schema-level
> >   mapping and whether we want data-level mapping, then what directions for
> >   the mapping(s) we want to handle. (I'd say "no, yes, both".)
> >
> >
> > I totally agree with this and I think that modelReference is sufficient if
> > providing a semantic match is the only concern. SchemaMapping becomes
> > important only during invocation, when the heterogeneties between the XML
> > data and the OWL instances have to be considered. Hence, I think that
> > option 1c) makes the most sense.
> >
> >
> > We have been working on the issue of providing mapping both ways. We call
> > it upcast (XML to ontological language) and downcast (ontological language
> > to XML).  I would like to share this paper that discusses some of the
> > heterogeneity that may arise and discusses as scenario that uses upcast and
> > downcast.
> >
> > Meenakshi Nagarajan, Kunal Verma, Amit P. Sheth, John A. Miller, Jonathan
> > Lathem, Semantic Interoperability of Web Services - Challenges and
> > Experiences, Proceedings of the 4th IEEE Intl. Conference on Web Services,
> > Chicago, IL, September 2006 (to appear).
> > http://lsdis.cs.uga.edu/library/download/techRep2-15-06.pdf
> >
> > Thanks,
> > Kunal
> >
> > --
> > Kunal Verma,
> > LSDIS Lab, Dept. of Computer Science,
> > University of Georgia.
> > URI: http://lsdis.cs.uga.edu/~kunal
> >
> >
> >
> 
> 
Received on Monday, 5 June 2006 15:49:40 UTC

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