- From: Jim Whitehead <ejw@cse.ucsc.edu>
- Date: Fri, 15 Jun 2001 11:51:13 -0700
- To: "WebDAV WG" <w3c-dist-auth@w3.org>
> > 2) A null resource MUST NOT appear as a member of its parent > > collection (RFC2518 sec 3). > > That's interesting, because Section 7.4 (which I was reading) states that > it MUST appear as a member of its parent collection.<g> > By copy to JimW. Please add this to the RFC2518 issues list. Actually, the specification is correct, though it takes a careful read to see that. There is a difference between a "null" resource, and a "lock null" resource. The definition of a "null" resource, as given in Section 3, is correct. Lock null resources are defined in Section 7.4. A null resource does not belong to its parent collection, and does not respond to UNLOCK. Perhaps a better way to express this concept is that what we termed a "null resource" is really an "unmapped URL". That is, the URL is not mapped to a resource. This avoids the philosophical question of "is a null resource a resource"? By calling it an unmapped URL, a "null resource" is clearly not a resource. A lock-null resource is a null resource that has been locked. A lock null resource has diferent properties that a null resource. Specifically, it has at least the lock discovery properties, and it is a member of its parent's collection. > > 4) Lock null resources (LNRs) are there to reserve name (RFC2518 > > sec 7.4). They are there so a client can reserve the name *before > > they create the resource* (store the "entity"). Admittedly, a > > server may use a file to represent the LNR, but thats an > > implementation detail. Since the name is reserved, it avoids > > potential conflict when the entity is actually stored e.g. with > > a PUT. > > I couldn't find the bit about "before they create the resource". > The use of a file is a red herring, I have never suggested that any DAV > server has to use files at all, in fact the opposite, I've always objected > to such statements. > If a lock null resource is not a resource, then what is it? Since a lock null resource has state, I would claim it is a resource. By the act of a client taking out a lock, they have likely made a mapping of a URL to a conceptual resource, and are int he process of fleshing out the computer representation of the conceptual resource. - Jim
Received on Friday, 15 June 2001 14:53:28 UTC