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Does DASL need to support structured queries?

From: Jim Davis <jdavis@parc.xerox.com>
Date: Tue, 17 Nov 1998 09:58:28 PST
Message-Id: <>
To: w3c-dist-auth@w3.org
If you have an opinion about whether or not DASL should support queries on
structured properties  *please* speak up in the DASL list, 

The rest of this email explains this further, and can be skipped if you
already understand what DASL is and what a query on structured properties
means for DASL.

DASL is the search protocol for WebDAV, it allows one to find resources
whose properties or content have values specified in the query, (e.g. find
resources whose date modified is > 19 Nov 1998 and whose text contains

WebDAV property values may be plain strings, but they may also be
structured values (expressed as XML elements on the wire).  The best
example of the latter is the WebDAV lock discovery property, but those who
have proposed WebDAV properties for Dublin Core metadata would likely also
use structured values.

DASL as currently defined provides means for searching string valued
properties but not within structured properties.  Thus one can not search
for resources based on the value of the lockscope or owner within a lock.
As a special concession to the need to search for collection/non-collection
resources, it provides an ad-hoc test to determine whether a resource is a

Thus the current DASL requirements ID does not include a requirement for
queries on structured properties.  We could say there is a rough concensus
that there is no requirement, but that would be based on having only one or
two opinions, scarcely a mandate.  We'd like to hear from more people one
way or the other.  In addition, if you think there *is* a requirement for
queries on structured values, please if possible, describe the layout of
the property values you expect to search, and the kinds of tests you think
you'd need.

For further information:

The DASL home page is http://www.ics.uci.edu/pub/ietf/dasl/

(Archived) mail messages of greatest relevance are:

Structure criteria for DASL queries
(tries to  "make (or reopen) the case for defining a structure criteria
(also called "structured query") in DASL.")
Should DASL have structure queries?
(Attempt to provoke discussion on the need for structured queries)

If you want to contribute to the design of DASL structured criteria, there
are two proposals on the table right now, or you can add your own.

Please see

initial proposal for structure criteria
(Davis's proposal for syntax for structured criteria)

Querying WebDAV Hierarchical Properties -- The Proposal
(Babich's proposal for structured query.)

Some background on the above

what kinds of structure criteria are needed?
(lists the structural features that must be testable)

Querying WebDAV Hierarchical Properties -- Motivation
(Design rationale for the Babich proposal)


Received on Tuesday, 17 November 1998 13:00:11 UTC

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