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RE: Status code for creating lock-null resource

From: Hall, Shaun <Shaun.Hall@gbr.xerox.com>
Date: Thu, 28 Jun 2001 13:49:32 +0100
Message-ID: <59697CCC6CE3D411B4CD00805FBB77672875D2@gbrwgcms03.wgc.gbr.xerox.com>
To: "'Alan Kent'" <ajk@mds.rmit.edu.au>, w3c-dist-auth@w3.org
Bits snipped. All IMHO...

> -----Original Message-----
> From: Alan Kent [mailto:ajk@mds.rmit.edu.au]
> Sent: 28 June 2001 06:56
> To: w3c-dist-auth@w3.org
> Subject: Re: Status code for creating lock-null resource
> Without the current LOCK semantics, you would have to do a PUT to
> create an empty file and then LOCK it. Does PUT have an OVERWRITE Y/N
> flag? (I dont have the spec handy). If it always overwrites, then
> there is the potential for a race condition.

There is no Overwrite with PUT. Unless you use one of the If-* headers, PUT
will overwrite the existing resource (assuming permissions etc are okay).
This is the kind of thing LOCK is suppose to deal with.

> Personally I would say tough luck. The above seems important in /tmp
> or C:\temp etc, but not on a WebDAV file system. And there are lots of
> potentials for race conditions in other parts of WebDAV arn't there?
> (OK, so I don't actually know of any...). So why worry about one case
> when it makes things so much more confusing overall?
> Alan

There are lots of conditions and requests that conflict with each other, so
it is important. In fact, some servers have "undefined" behaviour.

Am I the only person who actually has no real big problem with lock-null
resources (LNRs) ?


Shaun Hall
Xerox Europe
Received on Thursday, 28 June 2001 08:50:42 UTC

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