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RE: DELETE Semantics in Advanced Collections

From: Slein, Judith A <JSlein@crt.xerox.com>
Date: Fri, 21 May 1999 09:39:43 -0400
Message-ID: <201BB34B3A73D1118C1F00805F1582E801BA4DFB@x-wb-0128-nt8.wrc.xerox.com>
To: "'jamsden@us.ibm.com'" <jamsden@us.ibm.com>, "Slein, Judith A" <JSlein@crt.xerox.com>, "'WebDAV'" <w3c-dist-auth@w3.org>
It is a change, but we believe a benign one.  (It shouldn't conflict with
anything implementers of rfc 2518 are already doing.)

We are using the expression "collection member" as synonymous with "internal
collection member".  We've had some inconclusive discussion about whether
this change in terminology will cause confusion.  Opinions are welcome.

RFC 2518 said that collection members are URIs.  From conversations with the
authors, we believe their intent was that the members be URI segments.  We
are changing this to say that collection members are bindings, where a
binding is an association between a URI segment and a resource.  Since a URI
segment in its collection can be associated with only one resource, it
should be ok to treat the URI segment and the binding as (for practical
purposes) equivalent.  The URI segment identifies the binding.


Judith A. Slein
Xerox Corporation
800 Phillips Road 105/50C
Webster, NY 14580

> -----Original Message-----
> From: jamsden@us.ibm.com [mailto:jamsden@us.ibm.com]
> Sent: Thursday, May 20, 1999 6:58 PM
> To: Slein, Judith A
> Subject: Re: DELETE Semantics in Advanced Collections
> How does the definition of "internal member" change with 
> respect to these new
> definitions and binding semantics?
> "Slein, Judith A" <JSlein@crt.xerox.com> on 05/20/99 04:16:40 PM
> To:   "'WebDAV'" <w3c-dist-auth@w3.org>
> cc:    (bcc: Jim Amsden/Raleigh/IBM)
> Subject:  DELETE Semantics in Advanced Collections
> The authors of the advanced collections spec would like to get general
> reactions to the DELETE semantics that appear in section 4.2.8 of our
> current spec.  I've extracted some relevant definitions and 
> the text of
> 4.2.8:
> Binding
>      An association between a single path segment and a resource.
>      Because a binding is a member of a collection, a binding creates
>      one or more URL mappings to the resource.
> Collection
>      A resource that contains a set of bindings, termed member
>      bindings, which identify member resources.
> Member Binding
>      A binding that is a member of the set of bindings contained by a
>      collection.
> URL Mapping
>      An association between an absolute URL or URI and a resource. It
>      is possible for a resource to have zero, one, many, or even an
>      infinite number of URL mappings to URLs or URIs. Mapping 
> a resource to
>      an "http" scheme URL makes it possible to submit HTTP protocol
>      requests to the resource using the URL.
> 4.2.8 DELETE and Bindings
> The DELETE method requests that the server remove the binding between
> the resource identified by the Request-URI and the binding name, the
> last path segment of the Request-URI (with trailing slash, if 
> present).
> The binding MUST be removed from its parent collection, identified by
> the Request-URI minus its trailing slash (if present) and 
> final segment.
> If DELETE removes the last binding to a resource, the server MAY also
> reclaim system resources associated with the resource.
> Since DELETE as specified in [WebDAV] is not an atomic 
> operation, it may
> happen that parts of the hierarchy under the request-URI cannot be
> deleted.  In this case, the response is as described in [WebDAV].
> Section 8.6.1 of [WebDAV] states that during DELETE 
> processing, a server
> "MUST remove any URI for the resource identified by the 
> Request-URI from
> collections which contain it as a member."  Servers that support
> bindings SHOULD NOT follow this requirement.
> -----------------
> In addition, we are proposing to add to the specification an 
> All-Bindings
> header for use with DELETE.  This would request the server to 
> remove all of
> the bindings to the resource, and would allow the server (but 
> not require
> it) to reclaim system resources associated with the resource once the
> bindings were removed.
> --Judy
> Judith A. Slein
> Xerox Corporation
> jslein@crt.xerox.com
> (716)422-5169
> 800 Phillips Road 105/50C
> Webster, NY 14580
Received on Friday, 21 May 1999 09:39:43 UTC

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