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RE: [w3c_sml][Bug 4651] Definition of 'consumer' needs clarification

From: John Arwe <johnarwe@us.ibm.com>
Date: Thu, 12 Jul 2007 09:59:58 -0400
To: public-sml@w3.org
Message-ID: <OFED84057A.A062D8A7-ON85257316.004B1711-85257316.004CFF6F@us.ibm.com>
I am concerned that the note may have been mis-read, may be 
self-inconsistent, or both.  My evidence, pasted from the ref'd Note:
[Definition: A producer is an agent that creates text.]
[Definition: A consumer is an agent that consumes text.]
[easily missed caption under the first block diagram, bold mine] The 
diagram shows a simplification where the producer and consumer are 
relationships from agent rather than separate entities.
If I were to stick with the definitions as stated above, and ignore the 
"simplified" diagram, they are necessary but not sufficient wrt what we 
have in the SML specs for producer/consumer, because there is no notion of 
understanding.  An XSLT processor could consume SML/SMLIF text yet it has 
no concept of a model or references.
[Definition: An Act of Production is the creation of text.]
[Definition: An Act of Consumption is the processing of text of a 
"ok".  I still see nothing like SML/SMLIF's implications that their 
producers/consumers "understand" in any way the model(s) being processed.
[Definition: A Language consists of a set of text, any constraints on the 
information, and the mapping between texts and information.]
[Definition: Information is the result of processing, manipulating and 
organizing a text in a way that adds to the knowledge of the consumer.]. 
(Ednote: cribbed from wikipedia). [Definition: The information set of a 
language is the set of results of processing, manipulating and organizing 
each of the texts in a language.]
Building on the definitions above, I think I could find ways to define SML 
(and SMLIF) producers/consumers consistent with the above; SML and SMLIF 
are examplary languages.  SML maps texts like sml:uri to information 
(about a model).  SMLIF contains additional mappings for texts like 
smlif:definitions to the information that the XML infoset content of 
smlif:definitions consists of model definition documents.
In terms of how we could choose to use this information in our specs, one 
way would be:
1. Copy the relevant definitions into our spec(s), noting their origin 
precisely and that the ref'd origin is a WIP.
2. After some time has passed, e.g. in preparation for Last Call, re-check 
the status of the Note.  If by then it has become normative/stable, we can 
choose either to reconcile its then-current content with our definitions, 
or cut the cord to the original source and carry them independently. 
3. If it is still a Note, so we cut the cord above, at a later time when 
the Note transitions to a stable state and after SML/SMLIF are 
Recommendations, our descendants/followers can re-visit the "cut the cord" 
decision either in Errata or in a later version etc.
There are probably other ways to enable us to continue to make progress in 
parallel, suggestions welcome.

Best Regards, John

Street address: 2455 South Road, Poughkeepsie, NY USA 12601
Voice: 1+845-435-9470      Fax: 1+845-432-9787

"Wilson, Kirk D" <Kirk.Wilson@ca.com> 
Sent by: public-sml-request@w3.org
07/11/2007 09:37 AM


RE: [w3c_sml][Bug 4651] Definition of 'consumer' needs clarification

Just a note of clarification.  The consumer and producer relationships as 
defined in the TAG Note were not between consumer and producer.  Granted 
that relationship exists in some sense.  The consumer relationship as 
defined in the TAG Note is between the Agent and something called the Act 
of Consumption.  (Similarly for producer and the Act of Production.)
Kirk Wilson, Ph.D.
Research Staff Member
CA Labs
603 823-7146

From: Lynn, James (Software Escalations) [mailto:james.lynn@hp.com] 
Sent: Wednesday, July 11, 2007 9:16 AM
To: Wilson, Kirk D; public-sml@w3.org
Subject: RE: [w3c_sml][Bug 4651] Definition of 'consumer' needs 
I agree that these are better viewed as roles and perhaps this should be 
brought to the TAG's attention. I don't necessarily have a problem with 
the relationship concept, certainly there is a relationship between a 
consumer and producer. But at the same time, we don't want to imply that a 
producer cannot exist without a consumer. I would like to see comments 
from the rest of the group as to whether or not we should engage the TAG 
or just decide autonomously.
James Lynn 
W3C Service Modeling Language WG 
HP Software 
610 277 1896 

From: Wilson, Kirk D [mailto:Kirk.Wilson@ca.com] 
Sent: Wednesday, July 11, 2007 9:10 AM
To: Lynn, James (Software Escalations); public-sml@w3.org
Subject: RE: [w3c_sml][Bug 4651] Definition of 'consumer' needs 
I’m not sure I feel comfortable with treating “consumer” and “producer” as 
relationships (as defined in the TAG Versioning note).  More intuitively, 
IMHO, these are roles (interfaces) of (an) Agent.  Defining them as 
“relationships” would seem to me to introduce unnecessary complexity into 
a definition—you need to explain what the relationship is between, which 
means introduction an “Act of consumption”, e.g., as a separate entity (as 
per the Note).  Strange. 
Kirk Wilson, Ph.D.
Research Staff Member
CA Labs
603 823-7146

From: public-sml-request@w3.org [mailto:public-sml-request@w3.org] On 
Behalf Of Lynn, James (Software Escalations)
Sent: Wednesday, July 11, 2007 8:14 AM
To: public-sml@w3.org
Subject: [w3c_sml][Bug 4651] Definition of 'consumer' needs clarification
Regarding the use of the terms 'consumer', 'producer', and 'understand(s)' 
(the comments filed with bugzilla are below) I dug around the W3 website 
and found the following early draft of some work the TAG is doing.
[Editorial Draft] Extending and Versioning Languages: Terminology 
In Section 1.1 Terminology, this document briefly defines the terms 
'consumer' and 'producer' in ways that I feel are aligned with the way we 
are currently using and intend to use the terms.
The term 'understand' as relates to documents according to this and other 
documents in the References seems to simply mean "is able to process". It 
is worth noting that this document and others discuss the notion of 
"partial understanding" which is something we have touched lightly on in 
discussions, specifically that some consumers may only be able to (or 
choose to) process only parts of the model. There is a lot of discussion 
around this and I am not sure that it is all relevant to what we are 
discussing here, but if you want some background reading and a few pretty 
good analogies you can look at one of the references here:
 Web Architecture: Extensible languages. (See 
Since it seems that the TAG is attempting to standardize some of the 
terminology, I would suggest that we at least track the progress along 
these lines, i.e., consumer, producer, and understands. If this WG agrees, 
perhaps we should also offer our own comments to the TAG regarding the use 
of these terms.
This seems like enough for an initial discussion within the group so I'll 
stop here. I would like to point out that this is marked as FPWD so if we 
decide to track or work with the TAG on this terminology, we may need to 
postpone its resolution.
James Lynn 
W3C Service Modeling Language WG 
HP Software 
610 277 1896 
*** Comments from Bug 4651 : *** 
The definition of 'consumer' in section 3.1 troubles some WG members, 
in particular the verb "understands". 
In discussion during the ftf, various alternatives were proposed; 
what is the right way to distinguish consumers as described here 
from other processes or agents which might encounter an SML-IF 
message?  Are consumers processes which understand the model? (and 
if so, what does "understand" mean?)  Are they processes which 
"act on" the model (as opposed to the surface artifacts of 
serialization)?  Are they processes which validate the model?  (There 
seemed to be consensus that validation is NOT the right touchstone.) 
Further discussion of this concept is needed to reach agreement on what 
we want as a WG, in addition to whatever editorial effort is needed to 
capture that intent accurately and cleanly. 
In addition to the specific issue of the definition of 'consumer', the 
passage in question (and others) raise the related (and intertwined) 
question "What is it that consumers DO with SML-IF documents?"  The 
text says in various places that the consumer "understands" the document; 
this troubles enough of the WG that we should try to find some other verb 
that carries the right denotation and connotation and lacks the problems 
of "understanding". 

Received on Thursday, 12 July 2007 14:00:25 UTC

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