- From: John Arwe <johnarwe@us.ibm.com>
- Date: Mon, 10 Sep 2007 19:06:55 -0400
- To: public-sml@w3.org
- Message-ID: <OF1ED31F39.83932897-ON85257352.007EC322-85257352.007F1CB9@us.ibm.com>
This is more sensible than my original proposal (lax everywhere). Assuming
this is accepted by consensus, I would like the editors to add a
comment(s) (my preference, in the xsd) explaining the reasoning for each
case.
And thanks to Kirk for not letting us or the inconvenienced electrons sit
around doing other work :-)
Best Regards, John
Street address: 2455 South Road, Poughkeepsie, NY USA 12601
Voice: 1+845-435-9470 Fax: 1+845-432-9787
Pratul Dublish <Pratul.Dublish@microsoft.com>
Sent by: public-sml-request@w3.org
09/06/2007 11:24 PM
To
"public-sml@w3.org" <public-sml@w3.org>
cc
Subject
RE: [w3c sml] [4775] Change "skip" to "lax" processing
All
Yet another attempt to instigate consensus. This issue has been discussed
threadbare in this thread ;-)
We have a proposal from Sandy and Kirk to change all occurrences of “skip”
to “lax” in the SML IF schema except the occurrence on DataType (which
will continue to use “skip”).
Please speak up now if you disagree with Sandy and Kirk’s proposal -
silence will be treated as consent J
Thanks!
Pratul
From: Pratul Dublish
Sent: Thursday, September 06, 2007 8:27 AM
To: 'Wilson, Kirk D'; Sandy Gao; John Arwe
Cc: public-sml@w3.org
Subject: RE: [w3c sml] [4775] Change "skip" to "lax" processing
Kirk
Thanks for clearly articulating the two positions. I have a few
comments and a question:
1. “lax” becomes “strict” if the schema can be located
2. SMLIF spec says nothing about the syntax/semantics of the
extension points, and the extension points are irrelevant to the
validity/invalidity of an SML IF document. Therefore, why impose the
burden of attempting to locate the schema and validate them on all
processors?
3. A consumer who wants to validate the extension points can always
do so even if the SML IF schema specifies “skip”. E.g., this can be done
by “extracting” the extension points from an SMLIF doc and validating them
4. Question: Where is the apparent industry “best practice” re the
use of “lax” documented?
Pratul
From: Wilson, Kirk D [mailto:Kirk.Wilson@ca.com]
Sent: Thursday, September 06, 2007 6:19 AM
To: Pratul Dublish; Sandy Gao; John Arwe
Cc: public-sml@w3.org
Subject: RE: [w3c sml] [4775] Change "skip" to "lax" processing
I support Sandy’s fully articulated position, namely, that only DataType
should have processContents=”skip” for its content, and all other
extension points (content and attributes) should have “lax” processing.
Pratul, I don’t think the parallel between not worrying about the validity
(or invalidity) of the documents and not worrying about the validity of
the extension points is a good one. Presumably extensions points are
included for a reason and that reason probably has something to do with
the intended processing of the SML-IF document. Sandy’s point that
processors should enforce the SML IF structure does not imply what you
seem to be saying, that they is all an SML IF processor should do—note
Sandy’s parenthetical comment. IMO, those processors that are capable of
understanding the extension points should be able to validate them. Given
the ubiquity of processContents=”lax” in all other industry standards, I
don’t think it is much of a concern that all consumers that encounter
extension points are forced to try to validate them. (As I understand it,
if the schema can’t be located, then “lax” becomes in effect a
“skip”—i.e., the extension point is not declared to be invalid.)
Just trying to keep the discussion going. We seemed to have crystallized
on two positions:
1. Sandy’s position as articulated below (and in the first sentence
above), which follows apparent industry “best practices”, but with
sensitivity to the special needs of SMIL-IF
2. The “pure performance option”: maximize performance by skipping
validation on every extension point.
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 Pratul Dublish
Sent: Wednesday, September 05, 2007 5:21 PM
To: Sandy Gao; John Arwe
Cc: public-sml@w3.org
Subject: RE: [w3c sml] [4775] Change "skip" to "lax" processing
I agree with Sandy that SML IF schema should enforce the SML IF structure
and not worry about the validity (or invalidity) of the documents
contained in an SML IF document. IMO, the same logic should be applied to
the extension points since the extension points are provided for
extensibility but are irrelevant to the structure of the SML IF document.
My understanding of processContents=”lax” is that processors will attempt
to find the schema and, if successful, perform validation. Therefore, lax
validation on extension points will require all consumers (or more
precisely the XML Schema processor used by consumers) to attempt to locate
the schema for extension points and validate them. In fact, a producer who
uses extension points can force all consumers to validate them by
including the extension point schemas in the IF document. So, we should
retain skip processing for the extension points in SML IF schema.
From: public-sml-request@w3.org [mailto:public-sml-request@w3.org] On
Behalf Of Sandy Gao
Sent: Monday, August 27, 2007 6:47 AM
To: John Arwe
Cc: public-sml@w3.org
Subject: Re: [w3c sml] [4775] Change "skip" to "lax" processing
I agree with Kirk that this is (partially) a performance issue, because
"lax" allows/requires (1.0/1.1) the processor to try to assess the entire
subtree, whereas "skip" says "do nothing".
But there is a deeper issue here: what do we want the SML-IF schema to
enforce? I think the answer should be to make sure the document satisfy
the SML-IF *structure* (and any additional contracts/extensions between
processors). That is, if a document being transmitted is invalid, it
should *not* be a violation of the SML-IF schema. The IF is OK in this
case. (Just like "The Moon is bigger then the Sun" is OK English-wise.)
What this means is that whether it should be lax or skip depends on what
the wildcard is supposed to match:
- If it's for *extension" points (so that additional information can be
attached to the SML-IF instance, to be interpreted by processors who
understand it), then "lax" should be used, in case the processor has a
schema that can provide components to validate the matching
elements/attributes.
- If it's a place-holder for the document being transmitted, then "skip"
should be used, so that we don't let validity of individual document to
affect the overall IF validity.
Based on this, it seems that only "DataType" needs a "skip" wildcard for
its content (not attribute), and all the others should be "lax".
BTW, why did "DataType" have, as its content:
<xs:any namespace="##other" processContents="skip" minOccurs="0"
maxOccurs="unbounded"/>
I would think it should be
<xs:any processContents="skip"/>
<xs:any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
That is, we expect the first element to be the document being transmitted,
which can have any namespace (including that for SML-IF). This one is
"skip" because we don't care about its validity. This element must appear
once and only once. Then there are any numbers of additional elements that
can be used for extension purposes, hence "##other" and "lax".
Thanks,
Sandy Gao
XML Technologies, IBM Canada
Editor, W3C XML Schema WG
Member, W3C SML WG
(1-905) 413-3255 T/L 969-3255
John Arwe <johnarwe@us.ibm.com>
Sent by: public-sml-request@w3.org
2007-08-24 12:01 PM
To
<public-sml@w3.org>
cc
Subject
Re: [w3c sml] [4775] Change "skip" to "lax" processing
yeah, what he said (+1 from me)
I never understood why we would prevent a validator from using schema
components it could locate (skip), as long as they are not required (lax).
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
08/24/2007 10:49 AM
To
<public-sml@w3.org>
cc
Subject
[w3c sml] [4775] Change "skip" to "lax" processing
All,
The email will serve to initiate the discussion of whether we should
specify processControl=”lax” rather than the current “skip” for wildcards
in the SML XML Schemas.
There is only one occurrence of processControl=”skip” in the SML
specification: for the content of the smlerr:errorDataType.
The original issue was raised with respect SML-IF in which
processControl=”skip” is used for all extension elements (both xs:any and
xs:anyAttribute) in the type definitions of this specification.
Since I wasn’t involved in the original authorship of the spec, I’m not
sure what the rationale was for the original use of “skip”. I assume it
was for efficiency of the SML-IF consumer, the assumption being that the
SML-IF would need to concern itself only with sml elements according to
the semantics specified in SML-IF. In my notes I have found the following
definition of an SML-IF consumer: “processes SML-IF documents in whole or
in part by the semantics of this specification” (emphasis added). Since,
by definition, extension elements lie beyond the semantics of the spec,
there appears to be no reason for the processor’s attempting to validate
the extension elements. But I would consider this a poor argument.
“Skip” seems too finalistic and may not meet the requirements of SML-IF
consumer creators and SML-IF document authors who need to build in special
information, eg., into the ModelType, and can provide the schema for
validation (assessment). I suspect that something like this rationale
underlies what appears to be the industry “best practice” of using “lax”
processing. The cost of using lax processing is undoubtedly absolutely
minimal.
I will recommend changing the spec to “lax”, according to what is industry
best practice.
Kirk Wilson, Ph.D.
CA Inc.
Research Staff Member, CA Labs
Intellectual Property and Standards
Council of Technical Excellence
W3C Advisory Committee Representative
Tele: + 1 603 823-7146
Fax: + 1 603 823-7148
<mailto:kirk.wilson@ca.com>
Received on Monday, 10 September 2007 23:07:12 UTC