xml-dev - Re: XML Schemas: Best Practices

[Caroline Weller <caroline.weller@abs.gov.au>]

Caveat: I have not spent much time looking at XMLSchema yet.

 I do agree with the use of type:
user defined types of data that are used to define many elements that have
different purposes.
The handling of those different elements might be different.

An analogy from another area would be in object-oriented programming:
"When would you just instanciate a class (the element being the class),
and when would you create a subclass (the type being the parent class)"

Do people think this analogy is useful?

PS: love the spelling of Sydney, or maybe he meant the height of a guy called
Sidney?
:> being from Canberra, I found that quite amusing......


Caroline Weller
Australian Bureau of Statistics.



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|        |          "Roger L.    |
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  |       To:     xml-dev@lists.xml.org, "Ripley,Michael W."  |
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  |       cc:     costello@mitre.org, "Cokus,Michael S."      |
  |       <msc@mitre.org>, "Pulvermacher,Mary K."             |
  |       <pulver@mitre.org>, "Heller,Mark J."                |
  |       <heller@mitre.org>, JohnSc@crossgain.com, (bcc:     |
  |       Caroline Weller/Staff/ABS)                          |
  |       Subject:     Re: XML Schemas: Best Practices        |
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[Here's a response that I received directly.  Any comments on it?]

>"When should an item be declared as an element versus when should an
>item be declared as a type?"

I think it's a matter of style.  As you showed in your examples, you
can basically get done what needs to get done with either method.

My take on the style would be:

- use an element when all components of the element declaration will be
reused and semantically the reuse will mean the same thing (Elevation,
BostonElevation, FrankfurtElevation, SidneyElevation, etc.)

- use a type when the type definition will be reused for semantically
different elements (e.g., a 'money' type definition that is reused for
elements UnitPrice, Subtotal, ShippingAndHandling, Total, etc.).