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Re: Distributing versions across servers

From: Martin Bernauer <bernauer@big.tuwien.ac.at>
Date: Fri, 30 May 2003 15:10:44 +0200
To: <ietf-dav-versioning@w3.org>
Cc: <Edgar@EdgarSchwarz.de>
Message-ID: <000d01c326ac$e0d39960$d0a8a8c0@merzouga>

Hi Edgar,

thanks for answering. I will try to describe my problem from another

What I was interested in was whether WebDAV supports a version history that
comprises version resources stored on different servers.

I will try to explain it with a scenario, however, I will not use WebDAV
terms, because when I do, I am somehow constrained to the WebDAV model and
not able to say what I want to say. An abstract version (different from a
VR!) is for me a persistent snapshot of a document at a point in time.
Scenario: I create a document with some content and store it on server S1,
resulting in version V1. This version is then copied to server S2,
manipulated there by someone else, resulting in version V2, however, stored
at server S2. V1 and V2 constitute the document's version history.

Possible implementation with WebDAV (from my novice point of view): put
document (resource) under version control at S1, resulting in VCR1, VH1, and
VR1. Then copy VCR1 to S2 and put it under version control resulting in
VCR2, VH2, and VR2. Reading Section 3.14 from the spec, VH2 is empty.

Now, there is no metadata structure that describes the connection between
VCR1 and VCR2 (or VR1 and VR2, or VH1 and VH2), though from an application
point of view they constitute a single version history. Thus I would have to
implement a layer above WebDAV myself providing for the unified version
history. At least that is how I interpreted the spec... Is this true? Or is
there an alternative implementation with WebDAV that would preserve the
connection of (abstract) versions V1 and V2?

Regards, Martin

|-----Ursprüngliche Nachricht-----
|Von: ietf-dav-versioning-request@w3.org
|[mailto:ietf-dav-versioning-request@w3.org] Im Auftrag von 
|Gesendet: Freitag, 30. Mai 2003 12:23
|An: ietf-dav-versioning@w3.org
|Cc: Edgar@EdgarSchwarz.de
|Betreff: Re: Distributing versions across servers
|Hallo Martin,
|I'm not sure I completely understand what you want to achieve
|but will give it a try.
|> Is it possible in WebDAV versioning that the version resources of a
|> version history are distributed across mutliple servers?
|The version resource is defined as the distinct URL of a
|version. So if you do a checkin on a server I guess it makes 
|sense for the server to create an URL for itself because it 
|can't guarantee for any URL on another server to be available. 
|Please give more details if this isn't what you wanted to know.
|> For example, is it possible to allocate three versions V1, V2
|> (succeeding V1), and V3 (succeeding V2) on servers S1, S2, and S3 
|> respectively?
|What do you mean by 'allocate three versions' ?
|Is 'version' a 'version resource' or a 'version-controlled resource' ?
|MfG, Edgar
|edgar@edgarschwarz.de                  "http://www.edgarschwarz.de"
|"http://www.edgar-schwarz.de/forum/oberon"    Running Active Oberon
|Make it as simple as possible, but not simpler.     Albert Einstein
Received on Friday, 30 May 2003 09:10:48 UTC

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