Re: Fwd: [xml-dev] Not using mixed content? Then don't use XML

[Jim Melton <jim.melton@oracle.com>]

Simon,

I very often agree with your comments and observations, but I 
definitely do not on this subject.

Your statement is very much akin to my stating that all use of 
hammers is actively harmful.

The use of hammers when, say, polishing glassware is undoubtedly 
harmful.  Their use when building a house with a wood frame is 
indisputably good, even though a pneumatic nail gun might be better at times.

Schemata (of whatever sort) have great value in some environments, 
and cause many problems in other environments.  A categorical 
dismissal of the value of schemata under any and all circumstances 
betrays either arrogance, intransigence, or inexperience.

I've used XML schemata (DTDs and XSDs) for many years and they have 
served me very well.  Their use has helped me avoid many traps in 
data that I generate and in data that I accept from others, and they 
have amply paid for their use repeatedly.

Your experience is different.  That's fine.  I would never claim that 
"any situation in which the use of schemata is avoided is actively 
harmful", because it's obvious that is false.  It is also obviously 
false that use of schemata is always harmful.  My personal experience 
is proof of that -- I have benefitted from using schemata and I have 
encountered absolutely no problems as a result.

Sorry,
    Jim


At 4/7/2013 01:10 PM, Simon St.Laurent wrote:
>On 4/7/13 12:42 PM, Liam R E Quin wrote:
>>If you change "is" to "can be" then I'm OK with the statement, since I
>>believe that pretty much any technology or practice can cause problems
>>when mis-applied.
>
>Sorry, Liam.  I can't make that change.  In fact...
>
>>I prefer, however, to ask, "under what circumstances are XML Schemas
>>beneficial, and when can Schemas (of any kind) sensibly be used as a
>>design aid at or near the start of a project? What factors lead to
>>success and what factors lead to problems?"
>
>To repeat and expand:
>
>... schema-first or schema-centric design, any situation in which 
>the schema is considered more than a snapshot of current 
>conversational practice, is actively harmful.
>
>Schemas are in fact, most harmful if used as designed, as foundation 
>tools for describing vocabularies.  They may be less harmful if used 
>only as documentation, as a snapshot of practice, but even those 
>snapshots bring the risk of being used in ways that create deep brittleness.
>
>Again, I think that's true of all schema vocabularies, though 
>Examplotron usage seems likely to avoid heightening the second risk.
>  Schematron and Examplotron at least can be used for a variety of 
> different kinds of partial testing that can be used without 
> especially describing document structure.
>
>Thanks, and more soon,
>--
>Simon St.Laurent
>http://simonstl.com/
>
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========================================================================
Jim Melton --- Editor of ISO/IEC 9075-* (SQL)     Phone: +1.801.942.0144
   Chair, ISO/IEC JTC1/SC32 and W3C XML Query WG    Fax : +1.801.942.3345
Oracle Corporation        Oracle Email: jim dot melton at oracle dot com
1930 Viscounti Drive      Alternate email: jim dot melton at acm dot org
Sandy, UT 84093-1063 USA  Personal email: SheltieJim at xmission dot com
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=  Facts are facts.   But any opinions expressed are the opinions      =
=  only of myself and may or may not reflect the opinions of anybody   =
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