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Resend: WSA-WG: q. about WS defn

From: Geoff Arnold <Geoff.Arnold@Sun.COM>
Date: Fri, 26 Jul 2002 10:23:53 -0400
To: www-ws-arch@w3.org
Message-id: <502A110C-A0A3-11D6-A09D-000393991304@sun.com>

[Resent due to email UA screwup - the price I pay for
agreeing to participate in the pilot of a new mail
system! GA]

I'm sure this email is bound to cause some people to groan, "Oh
no! Not AGAIN!!". However in back-channel conversations
several people have encouraged me to risk that and submit
it anyway. So here goes.

I am confused about the basic definition of a web service, as 
quoted in the
Requirements doc. I recognize that some of the phraseology was probably
chosen to be deliberately ambiguous in the spirit of compromise,
but I hope that doesn't mean that there is no room for improvement.


     [Definition: A Web service is a software application identified by a
      URI, whose interfaces and binding [sic] are capable of being 
defined,
      described and discovered by XML artifacts and supports direct
      interactions with other software applications using XML based
      messages via internet-based protocols]

Questions:

(1) What does "by XML artifacts" mean? Definition/description and 
discovery
are quite different types of activity, and the meaning of "by" is quite
different in the two cases. "Defined by X" is ambiguous: it can 
mean "defined
in terms of X" or "defined by an active entity X". On the other hand,
"discovered by X" is idiomatically unambiguous, and implies that X 
is an active
entity capable of performing discovery. Are "XML artifacts" active 
entities?

Is the reader supposed to interpret this section as:

      whose interfaces and bindings are capable of being defined and
      described in terms of XML artifacts, and whose interfaces and
      bindings may be discovered using queries constructed from XML
      artifacts

(2) What does "and supports direct interactions with other 
software" mean?
I guess I have trouble with the words "supports", "direct", and "other".
In part the confusion arises from the preceding context, which includes
an implicit reference to an entity that is capable of discovering the
service; in this case, the "other" would seem to refer to some third
party - but this is probably NOT what was intended. "Support" is 
horribly
vague (intentionally so?), while "direct" would seem to imply that
INDIRECT interactions (whatever they might be) are NOT supported - but
why not?

(3) There is no explicit connection between the "interfaces and 
binding [sic]"
and the "XML based messages via internet-based protocols". It's not 
clear that
an implicit connection is strong enough. One approach might be to shift
the "XML based messages via internet-based protocols" to the beginning.
This would lead to something along the following lines.

      Definition: A Web service is a software application identified by a
      URI, whose interfaces and bindings are defined in terms of XML 
based
      messages transported by internet protocols. This definition, 
which is
      described using XML artifacts, can be discovered by other software
      applications, which may then interact with the web service in
      a manner prescribed by its definition.

This does include some repetition, but it also seems a lot clearer.

Geoff Arnold
Sun Microsystems Laboratories
Burlington, MA
Received on Friday, 26 July 2002 10:23:54 GMT

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