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RE: D-AR003.2

From: Dave Hollander <dmh@contivo.com>
Date: Tue, 23 Jul 2002 08:59:56 -0700
Message-ID: <BD52C6379806D51188DD00508BEEC96C4B6498@mail.contivo.com>
To: www-ws-arch@w3.org

I have seen no discussion on this CSF. Can we assume
there is consensus to drop it?

Dave Hollander

-----Original Message-----
From: Champion, Mike [mailto:Mike.Champion@SoftwareAG-USA.com]
Sent: Friday, July 19, 2002 5:23 PM
To: www-ws-arch@w3.org
Subject: FW: D-AR003.2




Posted on behalf of Dave Hollander:

-------------------------- CUT HERE ------------------------------------

Currently, D-AR003.2 says [2]
	"AC003 - is sufficiently extensible to allow for future evolution of
	technology and of business goals

	"D-AR003.2 description of Web Services be clearly separated
	into abstract descriptions ("what") from their concrete
	realizations ("how"), or put another way, separate design
	time aspects from run-time aspects"

My views:
	1) the two parts of the statement are substantively different.
	The first part is about level of abstraction (what/how) and the
	second is about binding (design/run-time).

	2) Drop the first part. WSDL already uses XML Schema. XML Schema
	is able to range in level of abstraction (from the concrete to
	abstract).

	3) Drop the second part. The runtime/designtime binding decisions
	historically change as technology matures. For us to set out
	principles about where the separation should be seems to
	counter-extensible.

	4) I fully support "declarative is scalable". I belive this is
	different than the two parts above. However, it seems too
	"apple pie" like to replace the current 3.2.


My Recommendation:
	Drop the CSF.

Regards,
Dave Hollander

---------------------------------------------------------------------
Mike C wrote:
"D-AR003.2 description of Web Services be clearly separated into abstract
descriptions ("what") from their concrete realizations ("how"), or put
another way, separate design time aspects from run-time aspects".

The intent seems to be to require the WSA to favor "declarative" rather than
"procedural" definitions, i.e. to define what happens, not how it happens.
This is related to the scalability goal because it is widely believed that
declarative approaches give the implementation much more scope to operate
efficiently, whereas procedural descriptions are too constraining.  For
example, SQL queries just specify the characteristics of the result,
old-style hierarchical database  queries specified how to navigate the
structure to find the result, and SQL has proven much more scalable.

The preliminary balloting was Y 10, L 3, D 1, O 1.  The "O" vote suggested
that it's an issue for the WSD WG.  Others suggest it's not clearly enough
worded.  In the mailing list Dave Hollander believes it's out of scope: "I
believe the idea comes from the often discussed modeling practice of
separation of abstract (what) from concrete (how). Unfortunately, there are
often reasons to violate this principle and there is disagreement in the
modeling community in where the line sits."  Others disputed the equation
between "abstract/concrete? and "declarative/procedural", and suggested a
re-wording to remove the "separate design time aspects from run time
aspects" to clarify that this is just a re-statement of the "declarative
definitions of a language are more scalable" orthodoxy.

I suspect that this issue could benefit from a bit more discussion to see if
Dave Hollander and others do indeed fundamentally disagree with the
"declarative is scalable" position.  If we can't come to a quick consensus,
I'd suggest dropping the CSF because the whole "declarative vs procedural
controversy" has been going on for a generation and will probably outlive us
all.

[1] http://lists.w3.org/Archives/Public/www-ws-arch/2002Jul/0216.html
[2] http://www.w3.org/2002/ws/arch/2/06/wd-wsa-reqs-20020605.html
Received on Tuesday, 23 July 2002 12:02:29 GMT

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