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RE: mid-course correction on abstract model for module processing

From: Williams, Stuart <skw@hplb.hpl.hp.com>
Date: Tue, 20 Mar 2001 11:41:42 -0000
Message-ID: <5E13A1874524D411A876006008CD059F192307@0-mail-1.hpl.hp.com>
To: "'marwan sabbouh'" <ms@mitre.org>, Yuhichi Nakamura <NAKAMURY@jp.ibm.com>
Cc: Mark Jones <jones@research.att.com>, xml-dist-app@w3.org
Hi Marwan,

> -----Original Message-----
> From: marwan sabbouh [mailto:ms@mitre.org]
> Sent: 19 March 2001 12:14
> To: Yuhichi Nakamura
> Cc: Mark Jones; xml-dist-app@w3.org; skw@hplb.hpl.hp.com
> Subject: Re: mid-course correction on abstract model for module
> processing
> In Stuarts Williams's abstract processing documents, module and handler
> > are explicity distinguished.  A module is a collection of blocks, and
> > a handler is a component which processes module(s).  I may just memorize
> > the terminology wrongly.
> I don't agree with this at all.  one o or more  Block is an instantiation
of a module.
> I thought ( and hope ) that we do not distinguish between them in the AM
> Stuart?

I've attached a copy of a response from a thread that started on the WG list
which I hope clarifies at least what I think. This particular thread ("Has
the semantics for Modules changed?") has evolved quite a bit on
w3c-xml-protocol-wg is accidental and it would be goodto cut further
discussion over to "xml-dist-app".



From: "Williams, Stuart" <skw@hplb.hpl.hp.com>
To: "'Jean-Jacques Moreau'" <moreau@crf.canon.fr>, "Williams, Stuart"
Cc: "'Mark Nottingham'" <mnot@akamai.com>, "Henrik Frystyk Nielsen (E-mail)"
<frystyk@microsoft.com>, "John Ibbotson (E-mail)"
<john_ibbotson@uk.ibm.com>, "Krishna Sankar (E-mail)" <ksankar@cisco.com>,
"Lynne Thompson (E-mail)" <Lynne.Thompson@unisys.com>, "Marc Hadley
(E-mail)" <marc.hadley@uk.sun.com>, "Mark A. Jones (E-mail)"
<jones@research.att.com>, "Martin Gudgin (E-mail)" <marting@develop.com>,
"Nick Smilonich (E-mail)" <nick.smilonich@unisys.com>, "Oisin Hurley
(E-mail)" <ohurley@iona.com>, "Scott Isaacson (E-mail)"
<SISAACSON@novell.com>, "Yves Lafon (E-mail)" <ylafon@w3.org>,
"'w3c-xml-protocol-wg@w3.org'" <w3c-xml-protocol-wg@w3.org>
Date: Wed, 14 Mar 2001 13:23:38 -0000
Subject: RE: Has the semantics for Modules changed?

Hi Jean-Jacques,

First the short answer: No, the semantics of Module has not changed (at
least from what I believe I have always held them to be - which is careful

So here's how Stuart thinks of it. Others of course may think different.

A module is a point of extensibility in our 'architecture'. A module is
defined in a specification (ideally someone writes down a description of a
module). The definition of a module contains syntactic rules/constraints
(eg. a schema) over the formation of 'blocks' associated with the module and
behavioural rules that govern the processing of 'blocks' associated with the


1) a Block is an instance of something that conforms to the syntactic rules
of a Module.

2) a Handler is an abstraction for an entity that realises the behavioural
rules of a module (and could in practice realise the rules for more than one

3) a Module is a unit of definition (eg. an authentication module) that
encapulates the syntactic and behavioural rules.

This means I think that we have 5 distinct concepts:

a) A module as a unit of definition - ie. it is abstract and its most
concrete realisation is a module specification cf. Signatures for SOAP.

b) Syntactic rules for the formation of XML protocol blocks (which are part
of a module specification).

c) Behavioural rules for the processing of XML protocol blocks associated
with a module )(also part of a module specification).

d) XML protocol blocks - syntactic elements in an XML protocol message
conforming to the syntactic rules of a particular XML protocol module.

e) XML protocol handler - an entity that realises the behavioural rules
associated with one or more particular XML protocol modules.

Personally, I think that the rules (syntactic and behavioural) collapse down
into the term module, while the instantiation of syntax and the
instantiation of behaviour match with block and handler respectively which
gets us back to our three terms Module, Handler and Block.

Does this help at all?


Received on Tuesday, 20 March 2001 06:42:02 UTC

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