[SML] Whether to support Attribute or not?

Eric Bohlman ebohlman at netcom.com
Sat Nov 27 20:28:41 GMT 1999


On Fri, 26 Nov 1999, Pavel Velikhov wrote:
> I am not a frequent participant here, but I am opposed 
> to the use of attributes in the XML as it is happening 
> right now. What I don't like is the way query languages 
> for XML suffer because of the attributes.
> 
> Attributes require a special syntax in the XML query 
> languages, just like in XML itself. Instead
> of writing OQL-ish path expressions like:
> 	homes.home.id
> 
> you will have to write:
> 	<homes> <home id=_ /> </homes> in XML-QL or similar
> languages. XQL also does not treat attributes and element
> equally.

But that's merely a design decision on the part of the designers of the
two query languages, *not* an inherent limitation.  It would be perfectly
possible to design and implement a query language that treated an
element's attributes the same as text-only child elements of that
attribute.

Do remember that XML is not inherently "object-oriented," whatever that
phrase means nowadays.  There are plenty of XML uses that involve
structured text, not serializations of objects.


> 
> If you don't know whether the object you are picking is an
> attribute or an element, you will have to write a disjunction.
> There could also be a case when an element has an attribute
> and a subelement with the same name, you might have to
> guard against such case. I.e. things get messy fast.
> 
> So I think if attributes are out, a lot of XML tools, including 
> query processors will get simpler. Also there will be less 
> opportunity for the users to screw up when using these tools.
> 
> Pavel Velikhov
> pvelikho at cs.ucsd.edu
> http://www.db.ucsd.edu
> 
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