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Subject: RE: XPATH query Take 2

A query and some opinions on queries  :

Firstly, I'd like to clarify something.

I understood that XPath statements like the examples shown are designed only
to return the _first_ object that matches the criteria, and that there is no
easy way to get any more matches using XPath.

At least, this is how XPath has worked in my usage of it so far, I have had
to write explicit tree walks, matching each node individually, to get more
than one match, as XPath "queries" have no 'history', so always returned the
same (first) match.

Are there DOM implementations that will return a nodeset rather than a
single node in response to such a request ?

If there aren't, then I don't see how XPath is a serious contender as a
query language, or that the XPath statements are, in fact, equivalents of
the OQL statements.

I also think that the OQL syntax is far easier to understand in general,
though if that really is the most complicated query you're ever going to
use* it probably doesn't make much difference.

(*it's a pretty simple one though, so be sure you don't need more. IME,
people always find they need more complicated queries further down the
track. )

I personallly feel the objection to the usage of OQL from certain parties is
commercially based rather than technically based*, because certain vendors
don't want to have to implement OQL to be compliant. I can see where they
are coming from, implementing OQL is a little harder**, but I don't agree
that an international standard should be compromised for the commercial gain
of a few small, but vociferous, vendors.

(*I've seen no arguments that there is anything actually _wrong_ with using
OQL, merely claims that everything needed can be done using XPath, so why
bother with OQL ? )

(** But not a lot harder, all they need is a transform to translate OQL into
XPath, and then use the existing XPath engine. Should be simple if the
claims of XPath being equivalent to OQL are correct...)

I'd also like to point out that XPath is _not_ the same thing as XML Query,
though XML Query _may_ make use of XPath syntax. Those arguing that we
should be sticking to XML standards should be arguing for support of XML
Query, not XPath, as XPath is _not_ the W3C's query recommendation for XML.


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