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- From: email@example.com (Ron Bourret)
- To: firstname.lastname@example.org, email@example.com
- Date: Thu, 1 Oct 1998 15:17:01 +0200
Amit Rekhi wrote:
> I am in the process of attaching datatype validation routines
> for element content in my XML file. I have come up with 2 approaches (as
> listed below)., but am not sure which is a better one. If someone could
> give their expert opinions ....
> APPROACH 1
> I can use NOTATIONS to identify data validation processes with element
> content. eg.
> <?xml version="1.0" ?>
> <!DOCTYPE start-ele [
> <!NOTATION Alphabet SYSTEM "AlphabetChecker.vld">
> <!NOTATION Number SYSTEM "NumberChecker.vld">
> <!ELEMENT start-ele (#PCDATA)>
> <!ATTLIST start-ele datatype NOTATION (Alphabet|Number) "Alphabet">
> <start-ele datatype="Number">123</start-ele>
> where AlphabetChecker.vld and NumberChecker.vld could contain validation
> routines for checking alphabet and number datatypes.
> APPROACH 2
> I embed my datatype validation scripts in the XSL file I attach to my XML
> data.I can embed my datatype validation scripts in HTML which will be
> outputted by my XSL file (I am using XSL to do XML -> HTML transformation)
> for elements in the XML file. In this case I could possibly use
> validation routines.
> Which of the 2 approaches is better?
> These 2 approaches bring out the basic questions:-
> Where to place datatype validation routines for element content, in the
> XML-DTD or in the XSL file attached to the XML data?
Of the two, I would probably use notations -- XSL is not yet finished and really
has nothing to do with data types. However, you should not assign the data type
on a per-element-instance basis as your example shows. This takes up extra
space and is prone to errors -- element foo is a number in one case and
alphabetic in another, which is probably not what you want. Instead, add a dt
attribute for each element type and assign a fixed default. This way, the data
type is fixed for a single element type.
Eventually, this information should go in a schema file (XSchema/DCD) and a
validating processor (or layer) will use built-in routines to do the checking.
If you are going to assign datatype attributes, you ought to look at/use the
data types in DCD.
-- Ron Bourret
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