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Re: live props on a VCR

From: Geoffrey M. Clemm <geoffrey.clemm@rational.com>
Date: Mon, 18 Dec 2000 00:07:39 -0500 (EST)
Message-Id: <200012180507.AAA01615@tantalum.atria.com>
To: ietf-dav-versioning@w3.org

   From: Greg Stein <gstein@lyra.org>

   The spec is pretty clear in 2.1.3 that dead properties of a version resource
   must also be exposed on the VCR. It also says that live props may differ.
   But it would be good to know if a VR's live props must also be exposed on
   the VCR.

   Specifically, I want to get the DAV:version-name from the VCR (rather than
   issue a second PROPFIND against the DAV:target of the VCR).

You could just use the property report to avoid the extra roundtrip, i.e. 
to get the version-name of the target of a vcr:

REPORT /whatever HTTP/1.1
... some headers ...
<D:property-report xmlns:D="DAV:">
  <D:target>
    <D:version-name/>
  </D:target>
</D:property-report>

   I don't see anything in the spec about exposing VR live props thru the VCR
   (I could have easily missed it so far). I'd like to state that they *are*
   exposed.

In general, the VCR live properties can differ from those of the
version identified by its DAV:target (e.g. creationdate,
getmodificationdate, etag, etc).  Currently, a server can implement a
VCR PROPFIND without traversing over to the target (which in a
distributed versioning system could exist on a different server).
There are some live properties (such as DAV:version-name and
DAV:version-history) that could be cached on the VCR because they only
change when you change the DAV:target, but I am concerned that this
blurring of the distinction between a VCR and the version identified
by the DAV:target of the VCR is likely to confuse implementers into
thinking that all the live properties of the VCR and the DAV:target
version have the same value.

Cheers,
Geoff
Received on Monday, 18 December 2000 00:08:39 GMT

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