Re: How to get the 1st element in DTDD

[Marcus Carr <mrc@allette.com.au>]

Murali Mani wrote:

> Yes, the schema should allow evolution -- does not this work?? -- allow
> changing type definitions and modification of the possible set of root
> elements, by adding new root elements -- the modules of RELAX and combine
> them using include and then add new root elements by having new interface
> element -- they add on to the existing root elements declared in the old
> interface element -- I am not very sure, but I think such document
> evolution should be the reason why RELAX is designed such.

I'm [blush] not that up to date on any of the various flavours of schema but
nonetheless, the paragraph above suggests that it is possible to achieve but
that it requires some configuration - it is this configuration that I would
strive to avoid. I would prefer that by default any element could act as the
root element and that I was responsible for restricting what does actually get
used.

> I deal with data after they are created -- for query purposes (possibly
> updates later on) -- I cluster documents based on the root -- for example
> if someone asks for //book/author I might not search in the documents
> whose root is say AutomobileStore, rather I might look among the documents
> whose root is only Library -- note that when I store, I do not actually
> allow a set of possible root elements -- it is more stringent -- only one
> root element -- though when we design, we keep the flexibility -- probably
> we might need to use this later as some trade-off or something.

Would it be fair to suggest that while the choice of the root element is of
crucial importance to your search, it may not of itself define value in the
data structure? In other words, others may use the same data in very different
ways but derive just as much value out of using a different root element? If
so, I guess it comes down to whether you consider the schema to be a
definition of the dataset or a specification for the application that will
make use of it. Both positions are probably valid, I would guess.


--
Regards,

Marcus Carr                      email:  mrc@allette.com.au
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Allette Systems (Australia)      www:    http://www.allette.com.au
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"Everything should be made as simple as possible, but not simpler."
       - Einstein