Re: [xml-dev] Stability of schemas -- frequency of versioning

[cbullard@hiwaay.net]

That this is a cost-benefit determination and not a frequency  
determination is so.   A schema with a frequency dependency is likely  
capturing information unsuitable for non-dynamic schemas.

The hard problem is determining the cost for any change given a  
multi-application environment.   One has to know specific information  
about different tools and how they are applied to the information as  
it works its way through a pipeline in which some tools are  
XML-capable and others are not.  For example, the challenge on my desk  
today is to write XSL to tranform tags being emitted from Word through  
a class (a la Russell) that adds tags based on style names.  These are  
essentially flat lists of different content types with little  
structure to do grouping operations, just name and position relative  
to other tags.  A schema change upstream would simplify the task.

Is it worth doing?  In terms of the XML itself, no not really.  In  
terms of Word, yes, possibly because the alternative is reentering  
thousands of items using an XML toolkit.  If the base of users  
includes enough organizations using Word, it's well worth it  
considering that the position of the item is irrelevant to the XML.

Offtopic, but there are days that functional programming truly sucks.   
Up translation is one of those tasks where the pain is barely worth  
the satisfaction.

len


Quoting Liam R E Quin <liam@w3.org>:

> On Mon, 2011-11-21 at 12:58 +0000, Costello, Roger L. wrote:
>
>> Suppose, however, that the information for a domain is required to
>> frequently change, say, three times a year.
>
> Generally there are constant or slowly-changing aspects, otherwise one
> wouldn't be able to characterise the domain at all.
>
> So you can develop a framework that's constant.
>
> For example, you might run a school with a list of students. You could
> have a rigid structure:
>     <chemistry year="3">
>       <david/>
>       <nicola/>
>       <simon/>
>     </chemistry>
> but if you did that, you'd have to change the schema each term
> (semester), or whenever a new pupil arrived or a current one left.
>
> So it would be better to have
>     <chemistry year="3">
>       <student>David</student>
> and so on, or,
>       <student ref="david" />
> and have a list of student records.
>
> Now the school will need to change the schema if the list of courses
> changes, and they may want to abstract those too.
>
> If there are really no constants, if everything changes unpredictably,
> get the hell out of there. Quicksand is dangerous, and you could lose
> your shoes!
>
> Liam
>
>
> --
> Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
> Pictures from old books: http://fromoldbooks.org/
>
>
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