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RE: datatyping is not needed

From: Jim Davis <jdavis@parc.xerox.com>
Date: Mon, 13 Jul 1998 12:19:58 PDT
Message-Id: <3.0.3.32.19980713121958.00828100@mailback.parc.xerox.com>
To: Marcus Jager <mjager@microsoft.com>, www-webdav-dasl@w3.org
At 11:33 AM 7/13/98 PDT, Marcus Jager wrote:
>Hi,
>
>Ummm, Did I miss something or didn't we need the datatypes so the server
>knows how to perform the relational operators (ge,le,... ) on the dead
>properties.

You may have identified a bad assumption on my part.  I could be wrong, but
here is what I was thinking when I asserted the lack of need.

It seems to me that there are two categories of dead properties, which I
might call the "obscure dead" and the "famous dead".  The obscure dead are
those the server knows nothing about, except that they are stored.  The
famous dead are those that are indexed by the server.  It seems to me that
to build an index, (e.g. a SQL table) the server must know at least a
little abou the dead property, e.g. the datatype.  How it knows this is out
of band, e.g. a server admin builds the table.

I was assuming that DASL implementations would only allow searching of the
famous dead, because it's too expensive to search the obscure ones.  For
the famous dead, the server already knows (and does not want the query to
specify a different datatype than what it knows).  The obscure are not
indexed and thus not searchable.

I could certainly imagine you arguing that this whole line of reasoning is
invalid because it is too influenced by current implementations.  But I am
strongly influenced by the design principle that one should try to
standardize current practise.
 
A second argument against datatyping in the query itself is that to be
meaningful, it would require DASL itself to define the semantics of
comparisons among the various datatypes, and this seems like a large topic.
 As it is, we not only leave the semantics undefined (is "10" less than
"9"?  As strings in alphabetic order, yes, as integers, "no") we don't even
provide a place to where the semantics would go.  Here, I think, doing less
is a good idea.

I'd be grateful for counter arguments.
Received on Monday, 13 July 1998 15:21:28 GMT

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