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Redmond: Collections Protocol - Modifying an Ordering

From: Judith Slein <slein@wrc.xerox.com>
Date: Thu, 25 Jun 1998 13:11:06 PDT
Message-Id: <3.0.3.32.19980625161106.009a7d00@pop-server.wrc.xerox.com>
To: w3c-dist-auth@w3.org
Once we decide to remove direct client access to an ordering property (see
mailnote on Scalability), we are faced with 2 issues about modifying
orderings.

1. It was suggested at Redmond that to change the position of a resource in
an ordering, we use MOVE with the Position header.  That is, the request
would look like this:

MOVE /arcticmaps/iceland.map HTTP/1.1
Host: www.ics.uci.edu
Destination: /arcticmaps/iceland.map
Position: After greenland.map

where the request URI and Destination header are the same, but Position may
differ from the current ordering.  However, the WebDAV protocol
specification says "The MOVE operation on a non-collection resource is the
logical equivalent of a copy (COPY) followed by a delete of the source."
If this semantics is really required, it is not possible to MOVE a resource
to the same location where it already resides.  I would welcome help from
the authors with whether I am misinterpreting the definition of MOVE. If we
can't use it to change the position of a resource in an ordering, we need
to define a new method for that purpose.

2. If PROPPATCH on the DAV:ordering property is not allowed, there is no
way to make multiple changes to an ordering in a single request.  A method
could be defined that would allow multiple changes to be submitted at once.
 There was controversy at Redmond about whether there really needs to be a
way to send many changes to the ordering in one request.  On the one hand,
if a user changes his mind after creating a collection about whether it
needs to be ordered, or wants to change the semantics of the ordering, it
seems unfortunate to have to send a separate request to re-position each
member of the collection.  On the other hand, this is probably a rare
occurrence and for small collections will not be a problem anyway.
Comments welcome.

--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 Thursday, 25 June 1998 16:05:31 GMT

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