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Re: schemaMapping issues breakdown (issue 6)

From: Kunal Verma <verma@cs.uga.edu>
Date: Tue, 30 May 2006 15:57:24 -0400
Message-ID: <8f9ef0aa0605301257k6780e728k52f10ccaccbb1ed6@mail.gmail.com>
To: "Rama Akkiraju" <akkiraju@us.ibm.com>
Cc: public-ws-semann@w3.org

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
>
>
>


-- 
Kunal Verma,
LSDIS Lab, Dept. of Computer Science,
University of Georgia.
URI: http://lsdis.cs.uga.edu/~kunal
Received on Tuesday, 30 May 2006 19:57:43 GMT

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