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Re: XSD feature check-lists

From: Pete Cordell <petexmldev@tech-know-ware.com>
Date: Thu, 4 Aug 2005 17:11:02 +0100
Message-ID: <007401c5990f$2ed5a640$b700a8c0@RW>
To: "Michael Kay" <mike@saxonica.com>, <noah_mendelsohn@us.ibm.com>
Cc: <xmlschema-dev@w3.org>

----- Original Message From: "Michael Kay"
To: "'Pete Cordell'"


> I think there are a number of processors that are very close to complete
> conformance, and it's very hard to capture their remaining restrictions on
> a
> simple tick-list.
> ...
> You'd need a pretty long feature list to capture things at that level of
> granularity.

I agree it would have to be quite detailed to be useful.  It wouldn't be a
simple 20 point check list, or something one could knock up over a weekend.
Then nothing is ever simple with XSD!

On the other hand, more than 150 points and it will lose usefulness also.

I think that we compare well on conformance also.  There are a few things we
want to do to improve more, but by the end of the year I'd hope we were in
the 99% region.  If the rest of the industry is in a similar position, maybe
such an exercise is not worth undertaking.

Pete.
--
=============================================
Pete Cordell
Tech-Know-Ware Ltd
                         for XML to C++ data binding visit
                         http://www.tech-know-ware.com/lmx
                         (or http://www.xml2cpp.com)
=============================================

>>
>> Dear Noah,
>>
>> While I see your point, I feel that XML schema is about 10 to
>> 20 times more
>> complex than an XML parser (a rough estimate based on implementation
>> experience).  Therefore, it isn't necessarily appropriate to
>> extrapolate
>> what has worked well for XML to XML schema.
>>
>> I also wouldn't expect vendors to fill in a feature profile
>> and never work
>> on their code again.  Quite the contrary - I can see that a
>> feature matrix
>> could be quite a battle ground and motivator for vendors to implement
>> features so that they can out do their competition.  This
>> would ratchet up
>> the level of support among vendors.
>>
>> The result would be that customers would have a clear picture
>> of what is
>> available, and vendors would know where they need to do
>> better.  If feature
>> support wasn't 100% after a while, standards people could go on about
>> vendors not properly implementing standards and add pressure
>> based on hard
>> evidence!  Looks Win-Win-Win to me!
>>
>> Regards,
>>
>> Pete.
>> ____________________
>> Original Message From: <noah_mendelsohn@us.ibm.com>
>>
>> > Pete Cordell writes:
>> >
>> >> I don't know whether this has been suggested
>> >> before, but as an alternative to defining domain
>> >> specific profiles of XSD, maybe the W3C can define
>> >> an official, standard checklist of features that
>> >> vendors can fill-in and display on their web
>> >> sites.  This would give customers an equal basis
>> >> for assessing products, and give vendors guidance
>> >> on where they can improve their products.
>> >
>> > I think that encouraging vendors to be honest about the
>> status of their
>> > products is a good thing, but appearing to encourage
>> subsets is not.  How
>> > would we feel if for XML itself we suggested a checklist
>> along the lines
>> > of:
>> >
>> > _ do you support attributes?
>> >
>> > _ do you support entities?
>> >
>> > _ do you support the short form of empty tags?
>> >
>> > _ do you handle whitespace correctly?
>> >
>> >
>> > etc.  XML interoperability would be seriously damaged.  The
>> point of XML
>> > is that you don't get a choice about these things and we
>> don't encourage
>> > reporting of subsets.  We tell you not to claim you're
>> XML-compatible
>> > until you do all of these things.  As a result, customers
>> find that XML
>> > interoperability is pretty good.
>> >
>> > The same concern applies to schema.  While a few vendors
>> are still having
>> > particular trouble and that is causing unfortunate confusion, my
>> > impression is that a number of the more careful XML schema
>> validators are
>> > showing quite good conformance and interoperability.  Of
>> course, there are
>> > some things like data binding tools that aren't even trying
>> to support the
>> > whole language, though some of the things they subset are in XML not
>> > schema (e.g. mixed content.)
>> >
>> > Bottom line: while schema does have well known complexity
>> issues, I think
>> > we should be very reluctant to promote ad-hoc subsetting in
>> particular
>> > implementations.  I'm afraid that publishing a matrix in
>> which you can
>> > document your non-conformance may appear to do just that.
>> >
>> > If you're talking about things like databinding tools, I
>> support what I
>> > took to be the consensus of the recent schema workshop:
>> tools should
>> > support all of schema and XML, but should optimize the
>> subsets most likely
>> > to be heavily used and/or a good match to the environment.
>> A checklist to
>> > document such a subset may make sense, and I think that as
>> a result of the
>> > workshop the W3C is considering a closer look at that area.
>> >
>> > --------------------------------------
>> > Noah Mendelsohn
>> > IBM Corporation
>> > One Rogers Street
>> > Cambridge, MA 02142
>> > 1-617-693-4036
>> > --------------------------------------
>> >
>>
>>
>> --
>> =============================================
>> Pete Cordell
>> Tech-Know-Ware Ltd
>>                          for XML to C++ data binding visit
>>                          http://www.tech-know-ware.com/lmx
>>                          (or http://www.xml2cpp.com)
>> =============================================
>>
>>
>>
>
>
>
>
Received on Thursday, 4 August 2005 16:11:49 GMT

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