W3C home > Mailing lists > Public > www-ws-arch@w3.org > December 2003

Re: new resource model

From: Mark Baker <distobj@acm.org>
Date: Fri, 19 Dec 2003 11:11:00 -0500
To: "Champion, Mike" <Mike.Champion@SoftwareAG-USA.com>
Cc: www-ws-arch@w3.org
Message-ID: <20031219111100.K7952@www.markbaker.ca>

I just wanted to say up front that I wasn't aware that the purpose of
this diagram was to relate the different models.  I thought it was
just to describe the model in its own terms.  So with that in mind ...

On Fri, Dec 19, 2003 at 01:03:07AM -0500, Champion, Mike wrote:
> > I wouldn't think that a resource model needs a separate 
> > discovery service.  Representations facilitate discovery.
> I think we in the WG generally see Google, etc. as well as UDDI registries
> (and ebXML registries?), not to mention the Semantic Web, as  discovery
> services.  It's hard for me to see how we could ignore all that and just say
> that somehow "representations facilitate discovery".  Sure, discovery
> happens by all sorts of means, manual and automatic, semantically aware and
> not, but it *does* happen, and agents that facilitate it are "discovery
> services."

Agreed.  But I also see my home page as a discovery service, as I can
link to anything with a URI from it.  So IMO, all resource-model services
can be discovery services.
> A Web server is a particular kind of service that provides representation
> transfer services, IMHO.

That's one way to look at it, sure, and a very useful way in some
contexts.  But here, I think it might be too confusing, as I think you
want to be able to distinguish between, say, a stock quote service
and a weather service on the same Web server.

As we're trying to relate diagrams here, I think it's probably
better to say something like;

service - is a - graph of resources
Web server - proxies for - resources
Web server - provides - representations
Web server - accepts - representations

> Recall that we've
> abandoned all hope of writing a W3C Recommendation and fitting this
> rigorously in with the Webarch, and are now trying to write down what *we*
> have learned from the exercise so that future travellers into this tar pit
> know where the really sticky places are.  

Ok, gotcha.  I don't want to get in the way of you folks documenting
what you've learned as a group.

> > BTW, I'd also suggest that the agent discovers the URI rather 
> > than the resource.
> Has the TAG said anything relevant to this point?  If not, and unless this
> is well established in linguistic philosophy or whatever,  I would prefer
> not to get into such a fine distinction.  In common language, one discovers
> the thing itself, not the identity of the thing.  In Web services, one
> probably wants to discover all the information about a service to see if it
> really does what one needs to do, not simply the URI of a service that is
> purported to do what one thinks one wants to do.  Just posing the issue
> makes my head hurt! 

I didn't think that would be controversial, as any software agent can
never know of me (a resource), only an identifier for me, and
representations of me.  But if you disagree, than I suppose that's
controversial by definition. 8-)

Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Received on Friday, 19 December 2003 11:13:05 UTC

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