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RE: Confusion: Removing a resource from version control

From: Clemm, Geoff <gclemm@rational.com>
Date: Wed, 13 Jun 2001 16:53:43 -0400
Message-ID: <3906C56A7BD1F54593344C05BD1374B1018E2472@SUS-MA1IT01>
To: ietf-dav-versioning@w3.org
   From: Lisa Dusseault [mailto:lisa@xythos.com]

   To rebut the earlier argument that clients need predictable
   behaviour -- well sometimes that goes by the wayside.  After all,
   that's what 404 Not Found was invented for.  Things disappear.

Having the server provide predictable behavior for a versioning
unaware client (and for that matter, a versioning unaware user) is
necessary but far from sufficient.  The hard part is to also support
an interoperable versioning-aware client for versioning aware
users.

A versioning aware user knows (and cares) whether old versions are
kept or not.  A versioning aware client needs to do what the
versioning aware user wants (not just some random behavior selected by
a versioning server implementer).  So that means if the versioning
aware user wants the versions to be deleted, the versioning aware
client needs to somehow delete those versions.  Similarly, if the
versioning aware user wants the versions to be kept, the versioning
aware client needs to somehow save those versions.

If the protocol defines the deletion behavior, an interoperable
versioning aware client can be written to produce whatever versioning
behavior the user expects.  If the protocol leaves deletion behavior
up to the server, then an interoperable versioning client would need
to determine what behavior the server has chosen to implement, and
then have separate code paths to deal with each of those behaviors
(in order to produce the effect expected by the versioning aware
user).

Note: If you primarily care about producing a specific behavior for
versioning *unaware* clients, and you don't care much about
interoperability with versioning *aware* clients, then you can just
support HTTP or 2518 WebDAV, and implement whatever versioning
behavior you want.  But if you want to support interoperability
between versioning aware clients, then you only get that by defining
explicit behavior for the server that versioning aware clients can
count on when they are implementing versioning behavior for a
versioning aware user. 

Cheers,
Geoff
Received on Wednesday, 13 June 2001 16:48:23 GMT

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