Response to LC-75 XML Schema Issue

Dear David Vun Kannon:

The XML Schema Working Group has spent the last several months
working through the comments received from the public on the last-call
draft of the XML Schema specification.  We thank you for the comments
you made on our specification during our last-call comment period, and
want to make sure you know that all comments received during the
last-call comment period have been recorded in our last-call issues
list (http://www.w3.org/2000/05/12-xmlschema-lcissues).

Among other issues, you raised the point registered as issue
LC-75. appinfo: Using appinfo annotations to store integrity constraints

Henry Thompson responded earlier to your comments and you 
acknowledged receipt, but we are unclear whether you considered
the response to be adequate.

Please review the discussion below, and respond as to whether
this resolution is satisfactory.



LC-75. appinfo: Using appinfo annotations to store integrity constraints
-------------------------------------------------------------------------

Issue Class: A Locus: structures 4.3.10 Cluster: 09 appinfo 
Status: unassigned
Assigned to: Frank Olken Originator: David Vun Kannon

Description

Is it an appropriate use of appinfo annotations to use them to 
store aplication-specific integrity constraints 
(e.g. SQL CHECK constraints)?

Interactions and Input

Cf. XML Schema considered inadequately extensible
Cf. Provide guidance on extending schema for schemas?

Input from Vun Kannon, David:
-----------------------------

"Vun Kannon, David" <dvunkannon@kpmg.com> to XML Schema Comments list, 
Mon, 1 May 2000 16:28:00 -0400 

I am considering, as the subject line says, using appinfo annotations 
to store integrity constraints. Consider a document as the transfer 
syntax for a database predicate. An integrity constraint might be 
"no worker earns more than their supervisor" or "pay_rate > 0". 
These integrity constraints could be expressed as CHECK constraints in
SQL, 
for instance. 

I was considering trying to achieve the same effect with XSL-T 
templates in appinfo elements. Unfortunately, it appears that 
even in the April 7 draft, annotation and appinfo are poorly documented. 
Annotation is used but not defined in either the schema for schemas 
or DTD, and appinfo (and documentation) similarly. What is the content 
model ()+ supposed to mean, in sec 4.3.10? 

Your comments appreciated on the appropriateness of the idea, 
and my understanding of appinfo. 


Input from Henry Thompson:
--------------------------
ht@cogsci.ed.ac.uk (Henry S. Thompson) to XML Schema Comments list, 
01 May 2000 21:46:13 +0100

"Vun Kannon, David" <dvunkannon@kpmg.com> writes: 

I am considering, as the subject line says, using appinfo annotations 
to store integrity constraints. Consider a document as the 
transfer syntax for a database predicate. An integrity constraint 
might be "no worker earns more than their supervisor" or "pay_rate > 0". 
These integrity constraints could be expressed as CHECK constraints 
in SQL, for instance. 


That's exactly the sort of thing appinfo is designed for. 
Sorry the documentation is less complete in this area than it should be. 
As the schema for schemas reveals, the content model for appinfo 
is constrained only in so far as it may not contain elements from 
the XML Schema namespace itself -- anything else, in any combination, 
is fine. 

So declare a namespace at the top of your schema, and put whatever 
you like from that namespace inside appinfo. If you give your schema 
validator a schema for that namespace as well as the schema for schemas, 
the contents of appinfo from that namespace will get schema-validated 
as well. 

Input from Vun Kannon, David:
-----------------------------
"Vun Kannon, David" <dvunkannon@kpmg.com> to XML Schema Comments list, 
Wed, 3 May 2000 11:53:02 -0400 

Got it. 



Is this response adequate ?
------------------------------

We (XML Schema Working Group) want to know your opinion
of our response to your last call comments.  This information
will be included with the package submitted to the W3C
Executive Director as part of the recommendation to take
the XML Schema Language to Candidate Recommendation.
We would appreciate your response as soon as possible.

Please choose from one of the following responses, adding 
whatever details, explanation you wish:

1)  "Good enough"  - You are satisfied with the Schema WG response
to your comments on XML Schema Language.  The response meets 
your requirements.  The matter may be considered resolved.

2) "Stop the presses"  - You are not happy with the response
to your comments on XML Schema Language.  Either the response
is unclear or inadequate.  The issue is of sufficient importance
and urgency that you want it called to the attention of the 
W3C Executive Director and you ask that the XML Schema Language 
delayed in advancing to Candidate Recommendation until the 
issue is resolved. 

3)  "Later - Version 1.1"  - You are not happy with the response,
but are prepared to defer reconsideration until XML Schema Lang.
Version 1.1 is drafted.  It is anticipated (hoped) that Version 1.1
will be completed by mid-2001.  Version 1.1 is intended primarily
to fix small issues needed by other W3C Working Groups to proceed 
with their work (especially XML Query Language).  You request that
your comments be reconsidered when drafting the Version 1.1 
requirements document.

4) "Later - Version 2.0"  - You are not happy with the response,
but are prepared to defer consideration until XML Schema Language
Version 2.0 is drafted.  It is anticipated that Version 2.0 would
not be completed until late 2001 or early 2002.  Version 2.0 may
include major revisions, e.g., multiple inheritance, etc.
You request that your comments be reconsidered when drafting the 
Version 2.0 requirements document.

5) "No longer care"  - You are not happy with the response, but
no longer care to pursue the matter, because ....



                  Frank Olken
                  XML Schema Language Working Group

  Lawrence Berkeley National Laboratory   (510) 486-5891 (voice)
  Mailstop 50B-3238                       (510) 486-4004 (fax)
  1 Cyclotron Road                        (510) 843-5145 (home)
  Berkeley, CA 94720, USA                 (510) 442-7361 (pager)

  E-mail:  olken@lbl.gov
  WWW:     http://www.lbl.gov/~olken/

Received on Thursday, 28 September 2000 20:42:32 UTC