ISO/IEC JTC 1/SC34 N0271
ISO/IEC JTC 1/SC34
Information Technology --
Document Description and Processing Languages
Title: |
Comments on N266 Proposed Requirements for Level 1 Model |
Source: |
Michel Biezunski, and
Steven R. Newcomb |
Project: |
Topic Map Models |
Project editors: |
Michel Biezunski,
Martin Bryan,
Steven R. Newcomb |
Status: |
Editors' Draft |
Action: |
For review and comment |
Date: |
30 November 2001 |
Summary: |
|
Distribution: |
SC34 and Liaisons |
Refer to: |
266 |
Supercedes: |
|
Reply to: |
Dr. James David Mason (ISO/IEC JTC1/SC34 Chairman) Y-12
National Security Complex Information Technology Services Bldg. 9113 M.S.
8208 Oak Ridge, TN 37831-8208 U.S.A. Telephone: +1 865
574-6973 Facsimile: +1 865 574-1896 E-mailk:
mailto:mxm@y12.doe.gov http://www.y12.doe.gov/sgml/sc34/sc34oldhome.htm
Ms.
Sara Hafele, ISO/IEC JTC 1/SC 34 Secretariat American National Standards
Institute 25 West 43rd Street New York, NY 10036 Tel: +1 212
642-4937 Fax: +1 212 840-2298 E-mail: shafele@ansi.org |
Comments on N266 Proposed Requirements for Level 1 Model
This document responds to document
N266.
The "Level 1" Model is intended to be a specialized application of the
Core Model that will establish a rigorous common understanding of the XTM 1.0
and existing HyTime-based ISO 13250:2000 syntaxes for Topic Map interchange.
Some features of N266 appear inconsistent with this intention:
- N266 describes itself as providing requirements for "the
foundational model" of Topic Maps. The Topic Maps standard cannot have both
a "Core" and a separate and different "Foundation". As far as we know, there is
no dispute that the draft Core model described in N243 and diagrammed in N244
is more "foundational" than the draft "Level 1" or "Infoset-based" model
described in N261.
- N266 says, "The foundational model shall describe the structure of
topic maps and the process of parsing them in such a way that conformant
implementations will be interoperable." The purpose of the Core Model can
correctly be perceived as being to render the problem of interoperability moot,
at least at a very general level. N266 would be a more useful requirements
document if it explicitly concerned itself with the interoperability of the
topic maps that employ functionalities, semantics, and syntaxes that the Level
1 Model builds on top of the Core Model.
- N266 says, "Anything that is not explicitly part of the model
shall not considered to be part of topic maps." This statement could be
misconstrued to mean that the Level 1 model defines what Topic Maps are, and
there is no need to refer to the Core Model.
- N266 says, "There shall be no such constraints that are not part
of the model specification." Again, this statement could be misconstrued to
mean that the Level 1 model defines what Topic Maps are, and there is no need
to refer to the Core Model.
- N266 says, "The data model shall be written in such a way that
third parties can write specifications defining the process of building
instances of the model from data sources other than the two standardized topic
map syntaxes." There is nothing wrong with this, but it will be unnecessary
to state it here if the Core Model meets its requirement to provide the
necessary rigorous conventions for defining Applications, and if the Level 1
Model conforms to the Core Model.
- N266 says, "The data model shall define the nomenclature for the
individual components of topic map structures." This is too broad. Some of
this nomenclature must be defined in the Core Model, and some of it in the
Level 1 Model.
- N266 says, "The data model shall capture the key constructs of
topic maps as first class entities..." At least some of "the key constructs
of topic maps" will be defined in the Core Model. It is not clear what N266
means by "first class entities", but it is clear that one of the key purposes
of making a distinction between the Level 0 (Core) and Level 1 Models is to
establish that some "entities" are more fundamental than others. Will we use
the term "zeroeth class entities" to describe the key constructs of the Level 0
Model?
There are several statements in N266 that appear to be intended to
impose constraints and requirements on the standard as a whole, and on the
standardization process, rather than on the Level 1 Model. These statements are
outside the scope of the purpose of N266.
- N266 says, "The foundational model shall be specified as part of
the ISO 13250 standard." As far as we know, there is no dispute about this,
but this statement doesn't belong here because it proposes a constraint on
other things than the Level 1 Model itself.
- N266 says, "The foundational model shall be 100% compatible with
every aspect of the implicit data model of XTM 1.0 that is actually defined in
the XTM 1.0 specification. This includes annex F." If adopted, this
requirement would constrain the process of standardization very severely,
leaving the Working Group in the position of being unable to fix problems that
remain in the XTM 1.0 Specification, even in the interests of achieving the
goal of establishing a Level 1 Model that will represent the consensus.
Regardless of the context within which it has been or may ever be made, this
purpose of this statement is at odds with the idea that normal ISO procedure
will govern the further development of the Topic Maps standard. This
requirement would have the effect of preventing due deliberation regarding any
of the many technical issues that were not adequately discussed in the process
that led to the publication of the XTM 1.0 Specification.
- N266 says, "The foundational model shall not contradict any
constraints on the model laid down by XTM 1.0, including those of annex F."
The same objection applies.
- N266 says, "The foundational model shall be 100% compatible with
the interpretation of the XTM 1.0 syntax as defined in XTM 1.0, including annex
F." The same objection applies.
- N266 says, "The foundational model shall be able to represent all
logically significant aspects of ISO 13250 topic map documents." This is
too vague; it is not clear what is meant by "logically significant".
- N266 says, "The foundational model shall not contradict any
constraints on the model laid down by ISO 13250, except in so far as they are
contradicted by XTM 1.0. In cases of discrepancy XTM 1.0 shall take
precedence." There are at least three problems with this extraordinary
requirement. (1) Discrepancies are a matter of the interpretation of each of
the standards. The interpretations of both standards must be fully agreed upon
before the implications of this requirement can be understood. (2) If adopted,
this requirement would privilege as-yet-unspecified interpretations of both
standards, and then demand that one of them must be preferred over the other.
Such a policy would prevent one or both of the interpretations themselves from
being adjusted in such a way as to achieve harmony. (3) It would be especially
inappropriate, in an ISO standards-making process, to require the prejudgment
of all technical issues in favor of the resolutions reflected in a publication
that emanated from a non-ISO process, preferring them even over the resolutions
reflected in a publication that resulted from the regular ISO process.
N266 says, "...nothing shall be included [in the Level 1 data
model] solely for the sake of preserving information about the syntactical form
of topic map documents." We think this is worded too strongly. For example,
it seems to mean that the addresses of the <topic> elements contained in
the syntactic representation of a topic map need not be retained in the data
model. Without knowledge of these addresses, it will be very hard to detect
when assertions are made by other syntactically-represented topic maps about
the subjects of such <topic> elements. It is essential to preserve
information about the syntactic representations of topic maps in order to
preserve the possibility of collaborative development of topic maps in modern
heterogeneous data and systems environments.