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Semantic of MOVE between working collections

From: Konstantin Knizhnik <KKnizhnik@togetherlab.com>
Date: Fri, 5 Apr 2002 13:49:41 +0400
Message-ID: <68948430591.20020405134941@togetherlab.com>
To: "'ietf-dav-versioning@w3.org'" <ietf-dav-versioning@w3.org>
Let's say we have VCR /somedir/foo.txt corresponding to version history
/repo/vh/vh1. Now consider the following sequence of requests:

1. Checkout source collection (create working collection)
Request:
        CHECKOUT <apply-to-version> /somedir
Response:
         Location: /repo/wr/wr1

2. Checkout target collection (create working collection)
Request:
        CHECKOUT <apply-to-version> /anotherdir
Response:
         Location: /repo/wr/wr2

3. Move resource from source to target collections
Request:
        MOVE /repo/wr/wr1/foo.txt  /repo/wr/wr2/foo.txt

4. Execute locate-by-history report for version history of this resource
Request:
        REPORT DAV:locate-by-history  /repo/vh/vh1
Response:
         ???
        
Which HREF will be returned by last locate-by-history report?
/somedir/foo.txt or /anotherdir/foo.txt or /repo/wr/wr2/foo.txt?


If answer is /somedir/foo.txt then behavior seems to be strange for
the client which performed this move - he had moved the file but find
it under the old path. But it is no (or minor) problems with implementing this
behavior.

If answer is /anotherdir/foo.txt, then the question is whether all
other clients will also receive the same answer for the same
DAV:locate-by-history request before /anotherdir collection is
checked-in? If so, it seems to violate one of the most significant
requirements to version control system - that uncommitted changes made
by some user will not be visible to all other clients.
Looks like the only consistent behavior is that the client which has
checked out /somedir and /anotherdir collection will see foo.txt under
path /repo/wr/wr2/foo.txt while all other clients will see it under
path /somedir/foo.txt until first client checkout these collections.
But how it is possible to implement it? To be able to implement such
behavior I need to somehow verify that user which have done CHECKOUT
of /anotherdir (or in other words owner of wr2 working resource)
is the same as user requested locate-by-history report. So to be able
to implement this behavior we need authentication and notion of
resource owner. But both are not part neither of WebDAV neither of
DeltaV specifications (DAV:owner is declared in WebDAV ACL draft, but
this standard in turn knows nothing about versioning). In other words,
semantic of MOVE can not be expressed in terms of the specification!

If answer is /repo/wr/wr2/foo.txt then in addition to questions and
problems described in previous section, there is one more question -
how it is possible in this case for this client to know path of
foo.txt resource? Lets say that client forgot that foo.txt was
members of /somedir collection and later was moved to /anotherdir.
So the only thing client knows is version of the resource. Can client
somehow request server about the parent of this resource?

-- 
Best regards,
 Konstantin                          mailto:KKnizhnik@togetherlab.com
Received on Friday, 5 April 2002 04:55:21 GMT

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