W3C home > Mailing lists > Public > www-ws-desc@w3.org > January 2007

RE: operation safety as semantic annotation?

From: Jacek Kopecky <jacek.kopecky@deri.org>
Date: Wed, 31 Jan 2007 22:34:22 +0100
To: Jonathan Marsh <jonathan@wso2.com>
Cc: 'WS-Description WG' <www-ws-desc@w3.org>
Message-Id: <1170279262.28268.203.camel@localhost>

Hi Jonathan, 

I was prepared to be OK with the duplicate information, having both
{safety} and {model reference} there. But I can easily see how I would
be against such duplication in cases where I didn't care about having
the information available in my favorite form. 8-) And you're right that
requiring understanding would be complicated.

I think {safety} is a bit of an oddster in WSDL - the whole spec is
about messages and here we have a statement about what operations do
(well, don't do). But, if the HTTP binding binds an operation to GET, it
would be making the same statement indirectly. And the missing
indication that an operation is safe might make somebody think about it
and check whether GET is really appropriate.

So I can see how the HTTP binding should have a reference to operation
safety, whether it is modeled as {safety} or {model reference} with
SafeInteraction in it.

To be frank, as the chair of the SAWSDL WG, I would very much welcome if
the WSDL group wanted to give us this annotation, and change the HTTP
binding to use that information instead of {safety}.

Understanding {model reference} as a WSDL extension is not a problem at
all in practice, it's such a simple thing. But it can be harder to

Thanks for putting it on the issues list, 8-)


On Wed, 2007-01-31 at 13:06 -0800, Jonathan Marsh wrote:
> AIUI, adding such an attribute would result in a {model reference} property
> being added to the WSDL, along with the {safety} attribute.  Are you OK with
> having duplicate information in the component model?
> Currently, the HTTP binding requires the wsdlx:safe extension be supported
> for interoperability.  Will it be clear that
> sawsdl:modelReference="http://www.w3.org/2006/01/wsdl-extensions#SafeInterac
> tion" is still required to be supported, but that the whole sawsdl
> extension, including any {model reference} properties, need not be?
> Right now we declare in the interchange format which extensions are
> supported, by URI (usually the namespace URI).  We would be unable to use
> the SAWSDL namespace URI to indicate this "safe sawsdl profile" extension is
> engaged - I guess we would continue to use the wsdlx namespace for this
> purpose.
> It all seems kind of messy.  My ideal would be to simply remove the
> wsdlx:safe and the {safety} attribute from WSDL and rely wholly on SAWSDL
> for this functionality.  The interaction between {safety} and the HTTP
> method selection is artificial IMO.  If one's intention is to use GET, then
> marking something as safe is no harder, and in fact one level more abstract
> and therefore tricky, than marking the whttp:method as GET. 
> Anyway, this will be issue CR147.
> Jonathan Marsh - http://www.wso2.com - http://auburnmarshes.spaces.live.com
> > -----Original Message-----
> > From: www-ws-desc-request@w3.org [mailto:www-ws-desc-request@w3.org] On
> > Behalf Of Jacek Kopecky
> > Sent: Monday, January 29, 2007 7:04 AM
> > To: WS-Description WG
> > Subject: RFC: operation safety as semantic annotation?
> > 
> > 
> > Dear all,
> > 
> > as you may know, the specification for Semantic Annotations for WSDL and
> > XML Schema [1] (SAWSDL) moving to CR. In our institute (my W3C hats are
> > off), we work on Semantic Web Services, and we plan to use SAWSDL as the
> > glue between our semantic description language and WSDL.
> > 
> > For my work, I will need to know the semantic description, i.e. what the
> > various service operations and data mean and do. One piece that I need
> > is operation safety. Currently, that is realized in WSDL as an extension
> > attribute, wsdlx:safe="boolean", with the default being false.
> > 
> > Operation safety is, at least to me, a clear semantic annotation. It
> > says nothing about the structure of the interface, instead it indicates
> > what the operation does (or rather, what it doesn't do - any side
> > effects or additional obligations in Web Architecture speak).
> > 
> > I would propose that we change the syntax from wsdlx:safe="true"  to
> > sawsdl:modelReference="http://www.w3.org/2006/01/wsdl-
> > extensions#SafeInteraction"
> > I know it's much longer, but please bear with me. 8-)
> > 
> > The WSDL Interface Operation {safety} property can stay as it is, only
> > its XML representation would change to "the IRI for SafeInteraction (as
> > above) will be included among the IRIs that are the value of
> > sawsdl:modelReference". The URI above is currently used in the RDF
> > mapping of WSDL to represent the safety property.
> > 
> > At worst, the people hand-writing and reading WSDL would have their
> > lives just a bit harder. At best, this would blend right in with the
> > plethora of other semantic annotations. Certainly, from my own point of
> > view, having safety as a semantic annotation as opposed to an extension
> > attribute would make my life just a bit easier.
> > 
> > Thanks for your consideration,
> > Jacek
> > 
> > [1] http://w3.org/tr/sawsdl
Received on Wednesday, 31 January 2007 21:41:11 UTC

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