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On Fri, 30 Aug 2002, Dare Obasanjo wrote:
> Two points
> 1.) XQuery's type system used to be based on regular tree grammars
> but this is no longer the case working group since they adopted W3C
> XML Schema as the basis of its type system. Now XQuery's data model is
> primarily based on named typing where the named types are W3C XML
> Schema types.
Their processing is based fully on regular tree grammars, the restrictions
such as 1-unambiguity and single type tree grammar has no relationship to
XQuery what so ever, to the best of my knowledge.
> 2.) Many vendors support the W3C and W3C XML Schema including IBM,
> Microsoft, Altova, Oracle, Sun, Tibco and the Excelon Corporation.
> These are just the companies I know off the top of my head, I'm sure
> if I did research I could name more. By the way, most people using
> SOAP, WSDL and XML web services are using W3C XML Schema directly or
> indirectly.
Yes, all I can say is they should also start supporting RELAX NG. Sitting
from academic front at this time, I have to decide between using what I
know is understandable and can be taught to students versus industry
pressure. It is a difficult choice probably, but several researchers have
chosen not to yield to industry pressure. It is sad that unlike relational
model where industry and academy (IBM and Berkeley) were in step, XML
schema, there is a big difference, right at the start.
Almost all the companies I have talked to say: "Wish XML Schema was not
like this". The compromise seems to be between correctness versus
industrial investment on an immature technology during the boom.. I think
the compromise at this point of time seems to be that industries support
both RELAX NG and W3C XML Schema, pressuring from the beginning will just
widen the gap..
<warning>speaking for himself only</warning>
cheers and regards - murali.
> -----Original Message-----
> From: Murali Mani [mailto:mani@CS.UCLA.EDU]
> Sent: Fri 8/30/2002 12:08 PM
> To: Maciejewski, Thomas
> Cc: 'xml-dev@lists.xml.org'
> Subject: Re: [xml-dev] what parsers support xml schema
>
>
>
>
> I use RELAX NG for my purposes. You can get details about RELAX NG from
> http://www.relaxng.org
>
> The following are purely my opinions, and the information I have gathered.
>
> RELAX NG is understandable and this is what academics use. RELAX NG is
> accepted in Japan as the standard, it is taught in schools in Japan,
> including the framework of regular tree grammars.
>
> The framework of regular tree grammars has found acceptance in several
> universities in US, which include University of Washington, Seattle,
> University of California, San Diego, University of California, Los
> Angeles, and University of Pennsylvania. These are the universities where
> I know there is work going on using regular tree grammars.
>
> These places have also found W3C XML Schema to be complicated and not that
> worthwhile. Further more, the processing of W3C's XQuery is based on
> regular tree grammars, though the initial typing might look as if it
> conforms to W3C XML Schema.
>
> Furthermore, there is some research at UCLA which argues that RELAX NG is
> better than W3C XML Schema for database modeling - the only thing that W3C
> XML Schema tried to solve, neglecting text modeling. Text modeling people
> use DTDs as they do not need data types to this date.
>
> It just so happens that RELAX NG came after W3C XML Schema, from the
> terrible discontent with W3C XML Schema. It is a very good schema
> language, and the design of the language is so very carefully thought of.
> The design principle can be summarized as -- collect requirements, then
> think really well about how to support them, and come up with
> mathematically elegant solutions which will support all the requirements.
>
> Who is pushing W3C XML Schema -- it seems like Oracle is one of the
> biggest pushers of this technology, the reason they say is they already
> have committed several dollars to W3C XML Schema. Even though they
> understand that RELAX NG is better than W3C XML Schema, they are finding
> it difficult to switch.
>
> I do not think such above restrictions as what Oracle faces applies to
> academic research. Furthermore, all we will say is industries should
> slowly start supporting RELAX NG also. I am sure there will be a migration
> at some point of time, question is when..
>
> The above is as unbiased an analysis as possible of the current state of
> affairs. I will say RELAX NG is a beautiful language -- simple, elegant,
> easy to use, and applies to several application scenarios several people
> have come across.
>
> <warning>speaking for himself only</warning>
>
> cheers and regards - murali.
>
>
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