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Overview of Core versioning

From: Lisa Dusseault <lisa@xythos.com>
Date: Fri, 16 Feb 2001 17:42:46 -0800
To: "Ietf-Dav-Versioning@W3. Org" <ietf-dav-versioning@w3.org>
Message-ID: <CNEEJCPIOLHKIOFNFJDPCEMPCDAA.lisa@xythos.com>
I've noticed that there is a "rationale" for versioning options, but not
for core versioning.  I think something is needed more than the no-op
definition of "the set of stuff defined in section 3".  Core is specific
enough that we should be able to describe, in a few brief paragraphs,
precisely what it accomplishes.  Thus, I've suggested some text which
can serve as an introduction to, overview of, and explanation of Core
Versioning.  It's important to frame and position technical
requirements, because readers understand technical specifications much
better if they understand what its for, and what it does, first.
 -- lisa

---

"Core versioning" is the set of properties and method semantics defined
by Section 3 of this document.  Core versioning serves to establish a
common model to organize and understand constructs which exist on any
versioning server.  Core versioning makes a number of requirements on
how servers must handle version-controlled resources, so that clients
have a reasonable model for what effect a command will have.

Core versioning makes requirements on servers but not on clients. The
intent of this choice is that clients be able to rely on a minimum level
of functionality when they contact a DeltaV-capable server. Since all
HTTP actions are initiated by the client, the server has no need to know
a priori what functionality the client supports. TO the extent to which
the server needs to know, the client can tell it in its requests.

A server which implements Core Versioning can interoperate successfully
with a client which is completely ignorant of DeltaV. Unless the client
requests versioning functionality, a Core-compliant server will
automatically behave like an non-versioning WebDAV server. Thus, a
versioned resource automatically behaves in an unsurprising way when
operated upon by WebDAV or HTTP methods.

A client can use OPTIONS to find out if a server supports core
versioning.  If the server does support core versioning, the client can
then be assured that it can:

 - Browse version-controlled resources and differentiate them from
non-versioned resources,
 - Use VERSION-CONTROL method to put resources under version control,
 - Browse past versions of version-controlled resources,
 - View some basic information about these resources,
 - Find out whether and how new versions will be created automatically
by the server (auto-version)
 - Predict what effect HTTP/WebDAV operations will have on a given
resource with a given version history
Received on Friday, 16 February 2001 20:43:45 GMT

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