Re: Choreography and the Semantic Web

I should have qualified 'nonsense'. I was specifically referring to SOAP 
which
you included in your pronouncement that I found to be absurd.

I know very well what RDF can and cannot do. By itself, it can do nothing. 
With a highly
sophisticated inference engine, and enough assertions about stuff to make 
some
sense of it, RDF can do what you say. The problem of course is that RDF is 
typeless
and much of what people want to plug into Web services is strongly typed. 
RDF
could just as easily say '%$#@ is the temperature', because it isn't 
typed, there's
not much that you can do to prevent this unfortunate occurance.

Then, there's also the issue of trust. Who's statements do you trust?

My point remains. SOAP can be used to express the state of a resource and 
WSDL can
be used at design time to prepare the software to receive that state (a 
priori knowledge
if you will). Sometimes, a priori knowledge is a "good thing".

Cheers,

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

www-ws-arch-request@w3.org wrote on 08/13/2002 09:37:09 AM:

> 
> On Mon, Aug 12, 2002 at 10:40:58AM -0400, Christopher B Ferris wrote:
> > > 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! 
> 
> All WSDL can do is describe the *interface* to a service that can return
> the temperature.  That is an entirely different thing than what RDF
> does, which is to provide a model that allows data to assert that the
> temperature is such-and-such a value.
> 
> WSDL is typically used (and principally supports) an early-binding mode
> of operation, so the client knows it's dealing with a thermometer, and
> therefore any data returned is known to be a temperature value.  REST,
> by virtue of being late bound, wouldn't know what the string "33" meant
> because the URI it invoked GET on is opaque to it, and it doesn't have
> any other info to go on.  So the data returned has to describe the type
> (and value, and relationships, etc...), which "33" doesn't.  This is
> what RDF does, and why it (or something similar, right Frank 8-) is
> critically required for machine processing on the Web.
> 
> As I said, it's no wonder Web services proponents don't generally see
> the value in RDF, because so much information about what you're
> interacting with is already known a priori.
> 
> MB
> -- 
> Mark Baker, CTO, Idokorro Mobile (formerly Planetfred)
> Ottawa, Ontario, CANADA.               distobj@acm.org
> http://www.markbaker.ca        http://www.idokorro.com
>