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PATCH Draft

From: James M Snell <jasnell@gmail.com>
Date: Mon, 25 Jun 2007 13:10:04 -0700
Message-ID: <4680211C.30700@gmail.com>
To: ietf-http-wg@w3.org, Lisa Dusseault <lisa@osafoundation.org>

Hello,

Recent revived interest in the ability to apply partial modifications to
Web resources led me to contact Lisa Dusseault regarding the status of
her expired PATCH draft [1].  After speaking with her a bit about it,
and considering the needs of things like the Atom Publishing Protocol
and other REST-based protocols, I have (at Lisa's invitation) prepared
an updated draft that builds on her original ideas and seeks to address
many of the concerns that had been raised.  The updated draft posted today:

  http://www.ietf.org/internet-drafts/draft-dusseault-http-patch-07.txt

The short story is this: to apply a partial modification of a Web
resource, use the PATCH method with a payload that describes the changes
to be made:

  PATCH /some/web/resource HTTP/1.1
  Content-Type: application/diff+xml

  [some-diff-format]

The server responds with...

  HTTP/1.1 204 OK
  ...

This draft evolves Lisa's original by dropping reliance on the
mechanisms defined by RFC3229 in favor of using Content-Type.  The draft
does not define any minimum-to-implement delta encodings and leaves it
completely open as to what kinds of formats can be considered "delta
encodings".

There are some issues that definitely need to be worked out.

  * Should there be a single minimum recommended diff format
    for binary/character based resources.  I know that this has
    been controversial in the past and I personally don't have
    an opinion on it.  I know that Lisa would prefer for there
    to be at least one minimum recommendation

  * Should it be possible to create new resources with PATCH

  * Should it be required to use If-Match and If-Unmodified-Since
    on PATCH.

I'm sure there are other issues :-)

Comments? Concerns?

- James

[1] http://www.ietf.org/internet-drafts/draft-dusseault-http-patch-06.txt
Received on Monday, 25 June 2007 20:10:14 GMT

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