Re: Choreography and the Semantic Web

Mark,

Please see below.

Cheers,

Christopher Ferris
Architect, Emerging e-business Industry Architecture
email: chrisfer@us.ibm.com
phone: +1 508 234 3624

Mark Baker <distobj@acm.org> wrote on 08/11/2002 03:11:35 PM:

<snip/>
> 
> A machine processable version of a form should work the same way.  The
> difference is that there's no human to punt to, so the server has to
> declare the type of document that it wants in return, rather than
> expecting a user to infer the type.  For example, it should say "send
> me a description of a person" (where "description of a person" is an
> RDF type identified by a URI), instead of "send me data", where the
> type of data is expressed only in a human-processable manner.

Huh? I don't understand your point here. Are you implying that WSDL
can only say "send me data"? 

> 
> The main difference between this approach and WSDL is that WSDL
> focuses on operations *and* data types, whereas the REST approach
> focuses on just data types, and fixes the operation.  Another way to
> look at that, is that receiving some WSDL lists the methods, but it
> doesn't tell you which method to invoke, meaning that the agent is
> expected to know that a priori.  Or as Paul has said, WSDL is
> principally a design-time artifact, not a runtime one like a form.

Right. The key point of the phrase being 'design time'. Personally,
I think that design-time and runtime aspects of WSDL should be more 
clearly
delineated and preferably separated, but that's another issue. The
key point is that, for many, it is the absence of design-time artifacts
that make it difficult to write software that replaces the human/user 
agent
element. 

By providing a) an ability to standardize on semantic expression of a 
service
and b) the ability of a service to expose to the world "here's what I 
do/understand, 
here's how you can interact with me" that can be used at design-time is an
important aspect currently missing from the Web.

> 
> > HTML, by virtue of being a very general format for human consumption
> > (i.e. all resources can have an HTML representation), solved this
> > problem for humans because there came an expectation that if you said
> > "Accept: text/html", you'd get something for the vast majority of
> > resources.  What we need, is a similar format/model for machines, such
> > as RDF.
> > 
> > <cbf>
> > So, what I read into this is you are saying "throw out WSDL and SOAP
> > and use RDF instead". What's wrong with replacing the 
application/rdf+xml
> > you suggest above with application/soap+xml and/or 
application/wsdl+xml?
> > </cbf>
> 
> SOAP and WSDL do very different things than RDF does.  SOAP and WSDL
> can't be used to express the state of any resource; you can't use them
> to say "the temperature is 33 degress celsius", for example.

Nonsense! 

> 
> I think that should answer Mike's question too.
> 
> MB
> -- 
> Mark Baker, CTO, Idokorro Mobile (formerly Planetfred)
> Ottawa, Ontario, CANADA.               distobj@acm.org
> http://www.markbaker.ca        http://www.idokorro.com