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Re: Type checking in DASL

From: Judith Slein <slein@wrc.xerox.com>
Date: Mon, 20 Apr 1998 10:57:20 PDT
Message-Id: <3.0.3.32.19980420135720.00a0c710@pop-server.wrc.xerox.com>
To: "Babich, Alan" <ABabich@filenet.com>
Cc: "'Hopmann, Alex'" <alexhop@Exchange.Microsoft.com>, "'Reddy, Saveen'" <sauveenr@Exchange.Microsoft.com>, "'Davis, Jim'" <jdavis@parc.xerox.com>, "'Reddy, Surendra'" <skreddy@US.ORACLE.COM>, "'Henderson, Rick'" <rickh@netscape.com>, "'Jensen, Del'" <dcjensen@novell.com>, "Babich, Alan" <ABabich@felix.filenet.com>, "'www-webdav-dasl@w3.org'" <www-webdav-dasl@w3.org>
I would strongly like to avoid putting datatypes into the query syntax.
There are several reasons for this.  

First, the syntax needs to stay simple if we expect anyone to implement it.  

Second, the server has other ways of finding out datatypes without having
to make them explicit in the query.  In cases where a DMS stands behind
WebDAV/DASL, it already knows the datatypes of properties and can figure
out whether a comparison in the query makes sense.  In the more general
case, DAV properties are identified by URIs.  Although it is not required
that a property definition reside at that URI, we can hope that the world
will evolve to the point where there will be a property definition,
including a datatype, at that location, and that practice will eventually
converge on some standard syntax like the one proposed by XML-Data for it.
I don't think DASL should say anything about a syntax for typing data, but
should just wait for practice and standards to sort themselves out.  We can
make sure the XML-Data folks know we are depending on their work, and can
provide input to that standard to make sure it does meet our needs.

Third, even if in the short term there are difficulties in figuring out the
datatype of a property, there is no reason why the client should have any
better information about it than the server does.  So put the burden on the
server and keep it out of the query syntax.

--Judy

Name:		Judith A. Slein
E-Mail:		slein@wrc.xerox.com
Phone:  	(716) 422-5169
Fax:		(716) 422-2938

Xerox Corporation
Mail Stop 105-50C
800 Phillips Road
Webster, NY 14580
Received on Monday, 20 April 1998 13:53:46 GMT

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