W3C home > Mailing lists > Public > www-ws-desc@w3.org > June 2003

Comments on the pretty pictures

From: Amelia A. Lewis <alewis@tibco.com>
Date: Thu, 12 Jun 2003 12:25:56 -0400
To: WS Description List <www-ws-desc@w3.org>
Message-Id: <20030612122556.4e912177.alewis@tibco.com>

In brief,

The nice pretty pictures in part 1, section 1.1 (figure 1-1 and 1-2) are
certainly *pretty*.  The definitions embedded in them are completely
innovative, however, and innovative in a way I would argue encourages
maximum incomprehension.

The use of "resource" as a larger thing than "service" is a reversal of
common use.  Commonest-of-all use of "resource" is in the terms "uniform
resource locator" or "uniform resource identifier"; these terms
implicitly define a resource as being an endpoint and an interface; the
fact that multiple resources may point at the same abstract [something],
or share its state, indicates that the general use of the term
"resource" is to indicate a subset of an interface on a service.

Possibly something could be recovered by using a different term. 
Redefining "resource" to be big-big-big in direct contradiction to its
common usage is likely to produce massive email and teleconference
discussions, due to confusion over the actual meaning of the term. 
Among other things.

The definition of "service" in these graphics is that a service is a
subset of a (web) service.  Again, innovative language.  Possibly,
though, it is not best to define a service (element) to be a subset of a
(web) service.  Service is a subset of a service is less than ... ideal.
 At best.

These linguistic issues show up a fundamental conceptual problem.  If we
have an element called "service", then it is sensible, reasonable, and
intuitive that the element represent a web service; this interpretation
is commonly applied to WSDL 1.1 documents, even though the service
element is underspecified in that specification.

Use of the term "service" to mean something other-than, smaller-than,
a-subset-of, related-to a web service is necessarily unreasonable,
non-intuitive, and ... nonsense, in a word.  Making life harder for
folks who have to train the folks who will be using WSDL ("Well, a
service *element* isn't an actual *web* service.  It's ... umm, well, it
may be a *part* of a web service, and we'll call that web service a
"resource", so now we can find all the parts of a web service by
relating them with a "target resource" attribute, but now we're not
using the term "resource" in the same way that it's used in a URI or
URL, so please ... make your mind a _tabula rasa_, if you would, and we
will redefine all the words that we plan on using.") is probably not the
ideal means of encouraging early adoption of the specification.

Now, in WSDL 1.1, portType <- binding <- service/port

In WSDL 1.2:
  interface <- binding <- service/endpoint
  interface <- service

No gain, just the introduction of redundancy, with no possibility of
removing it (are we going to suggest that the relationship between
interface and binding can be broken?  between binding and endpoint?).


Amelia A. Lewis
Architect, TIBCO/Extensibility, Inc.
Received on Thursday, 12 June 2003 12:25:17 UTC

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